FUEL CELL STACK, DUMMY CELL FOR A FUEL CELL STACK, METHOD FOR MAKING A DUMMY CELL

Abstract

Fuel cell stack (10), comprising: a stacking body (14) comprising a plurality of power generating cells (12) stacked together in a stacking direction, wherein the power generating cells (12) each comprise a membrane electrode assembly (80), a resin / plastic frame element (82) provided around the membrane electrode assembly (80), and separators (32, 36, 38) sandwiched between which the membrane electrode assembly (80) is arranged, wherein the membrane electrode assembly (80) comprises an electrolyte membrane (84) and electrodes (86, 88) provided on both sides of the electrolyte membrane (84), wherein the electrodes (86, 88) each have a gas diffusion layer (92, 96) made of an electrically conductive porous body; a dummy cell (18, 20, 24) which is provided in the stacking direction at at least one end of the stack body (14); wherein the dummy cell (18, 20, 24) comprises a dummy arrangement (110) corresponding to the membrane electrode arrangement (80), a dummy resin / plastic frame element (111) provided around the dummy arrangement (110), and dummy separators (105, 108, 130) between which the dummy arrangement (110) is sandwiched; characterized in that the dummy arrangement (110) is formed by stacking together three electrically conductive porous bodies (112, 114, 116), each of which has a different surface area, the three electrically conductive porous bodies (112, 114, 116) are stacked to form a stepped surface at an outer edge section of the dummy arrangement (110), and the dummy resin / plastic frame element (111) is connected to the stepped surface.

Description

Background of the inventionField of the invention:

[0001] The present invention relates to a fuel cell stack comprising a stacked body and a dummy cell. The stacked body is formed by stacking a plurality of power generation cells in a stacking direction. Each of the power generation cells includes a membrane electrode assembly, a resin / plastic frame member arranged around the membrane electrode assembly, and separators. The dummy cell is provided at least at one end of the stacked body in the stacking direction. Furthermore, the present invention relates to a dummy cell for a fuel cell stack and a method for manufacturing the dummy cell. Description of the related prior art:

[0002] A solid polymer electrolyte fuel cell generally uses a solid polymer electrolyte membrane (hereinafter referred to simply as the electrolyte membrane). The solid polymer electrolyte membrane is a polymer ion exchange membrane. The fuel cell includes a membrane electrode assembly (MEA) comprising an anode provided on one surface of the electrolyte membrane and a cathode provided on the other surface of the electrolyte membrane.

[0003] The membrane electrode assembly is sandwiched between the separators to form a power generation cell, and a plurality of the power generation cells are stacked together to form a stacked body. To form the fuel cell stack, power collection terminals for collecting electrical charges generated by power generation in each of the power generation cells and end plates for holding the power generation cells in the stacked state are provided at both ends of the stacked body in the stacking direction.

[0004] Since heat radiation in the stacking direction from the ends of the stacked body (hereinafter also referred to simply as the end(s) or end(s)) is facilitated by terminal plates, etc., the end(s) of the stacked body in the stacking direction tend to have a low temperature compared to the middle side of the stacked body in the stacking direction. When the temperature of the end(s) of the stacked body becomes low due to the influence of the external temperature, etc., and water condensation occurs, there is a concern that the fuel gas and the oxygen-containing gas (reaction gases) will not be evenly diffused, and the desired power generation stability of the fuel cell stack cannot be achieved.

[0005] To solve this problem, for example, in a fuel cell stack disclosed in Japanese Patent JP 4 727 972 B2, so-called dummy cells are provided in the stacking direction at at least one end of the stack body. Since metal plates are used in the dummy cells instead of electrolyte membranes, no power generation is performed and no water is generated. The dummy cells themselves therefore act as heat-insulating layers between the terminal plates and the stack body. By providing the dummy cells as described above, it is thus possible to suppress a temperature drop at the end of the stack body. That is, it is possible to reduce the influence of the external temperature on the fuel cell stack and improve the stability of power generation.

[0006] The document DE 11 2014 004 462 T5 discloses a fuel cell stack according to the preamble of claim 1, a dummy cell according to the preamble of claim 20 and a method according to the preamble of claim 21.

[0007] Furthermore, reference is made to the documents DE 10 2014 210 358 A1 and US 2006 / 0 110 650 A1. SUMMARY OF THE INVENTION

[0008] It is a main object of the present invention to provide a fuel cell stack which makes it possible to improve power generation stability.

[0009] Another object of the present invention is to provide a dummy cell for a fuel cell stack, which makes it possible to improve power generation stability.

[0010] Yet another object of the present invention is to provide a method for manufacturing a dummy cell which makes it possible to improve power generation stability.

[0011] According to one aspect of the present invention, a fuel cell stack according to claim 1 is provided.

[0012] In the fuel cell stack, the dummy assembly of the dummy cell is formed by stacking three electrically conductive porous bodies together. Unlike the dummy cell of the comparative example, which uses a metal plate instead of the electrolyte membrane of the membrane-electrode assembly, the dummy assembly with such a structure can be obtained at low cost because it eliminates the need to provide elements made of a variety of materials, such as the electrically conductive porous body and the metal plate. Since the dummy assembly is made of the electrically conductive porous body, and the gas diffusion layer of the membrane-electrode assembly is also made of the electrically conductive porous body, it is possible to reduce the cost of providing components associated with the dummy cell.

[0013] Furthermore, the dummy assembly is formed by stacking the three electrically conductive porous bodies with different surface areas to provide steps for connecting the dummy resin / plastic frame member in its outer edge portion of the dummy assembly. For example, without a special manufacturing process for providing a step in an outer edge portion of the electrically conductive porous body integrally formed in one piece, it is possible to obtain the dummy assembly relatively easily.

[0014] By providing the above dummy arrangement, it is possible to provide each of the dummy cells with a simple and inexpensive structure.

[0015] Since the dummy cell comprises the dummy assembly corresponding to the membrane electrode assembly and not the membrane electrode assembly, no power generation is performed, and thus no water is generated as a result of power generation. Thus, the dummy cell itself acts as a thermal insulation layer, and it is possible to suppress condensation and / or freezing of water in the dummy cell. By providing the dummy cell in the stacking direction at at least one end of the stacked body, it is possible to improve the thermal insulation performance at the end of the stacked body. Therefore, even in a low-temperature environment, it is possible to suppress a temperature drop at the end of the stacked body compared to the central position of the stacked body.

[0016] Furthermore, since it is possible to improve the thermal insulation performance at the end of the stack body even in the case of commissioning the fuel cell stack in the sub-freezing temperature environment, it is possible to effectively increase the temperature of the entire stack body.

[0017] Therefore, it is possible to suppress voltage drop due to freezing of produced water, etc. at the end of the stack body.

[0018] Thus, in the fuel cell stack, it is possible to suppress the influence of the outside air temperature on the fuel cell stack and improve the stability of power generation by using the dummy cell, which has a simple and cost-effective structure.

[0019] Preferably, in the above fuel cell stack, each of the power generation cells and the dummy separators has a channel for an oxygen-containing gas configured to allow an oxygen-containing gas to flow in the stacking direction of the stacked body, and a channel for a fuel gas configured to allow a fuel gas to flow in the stacking direction of the stacked body, and a separator of the separators facing one of the electrodes of the membrane electrode assembly has a flow field for an oxygen-containing gas along which the oxygen-containing gas flows, another separator of the separators facing another of the electrodes of the membrane electrode assembly has a flow field for a fuel gas along which the fuel gas flows, a first gap corresponding to the flow field for an oxygen-containing gas,A second gap corresponding to the flow field for a fuel gas is formed between a dummy separator of the dummy separators, which faces one end side of the dummy assembly in the stacking direction, and the one end side of the dummy assembly. A second gap corresponding to the flow field for a fuel gas is formed between another dummy separator of the dummy separators, which faces another end side of the dummy assembly in the stacking direction, and the other end side of the dummy assembly. A communication channel configured to allow a flow of the oxygen-containing gas is provided between the oxygen-containing gas channel and the first gap. A blocking part configured to block a flow of the fuel gas is provided between the fuel gas channel and the second gap.

[0020] The oxygen-containing gas is supplied to the inlet side of the oxygen-containing gas channel of the fuel cell stack in a humidified state. The water vapor in the oxygen-containing gas is condensed into condensed water in the liquid state, and the condensed water is injected into the power generation cells, which can undesirably reduce the diffusion efficiency of the fuel gas and the oxygen-containing gas (reaction gases).

[0021] Since the oxygen-containing gas passage and the first gap adjacent to one end of the dummy assembly in the stacking direction are connected by the connecting channel in the fuel cell stack, the oxygen-containing gas flows through the first gap. Therefore, even if the oxygen-containing gas contains condensed water, the condensed water is collected by the dummy cell, and it is possible to prevent the condensed water from splashing into the power generation cells.

[0022] Furthermore, in the dummy cell of the fuel cell stack, since the blocking part is provided as described above, the fuel gas flowing through the fuel gas channel does not flow through the second gap adjacent to one end of the dummy assembly in the stacking direction. Since the fuel gas does not flow through the second gap, the thermal insulation performance in the second gap is increased, and the second gap functions as a thermal insulation space. Accordingly, it is possible to greatly improve the thermal insulation performance by the dummy cell. Furthermore, it is possible to reduce the amount of fuel gas discharged from the fuel cell stack without contributing to electrochemical reactions for power generation.

[0023] Thus, by providing the connecting channel and the blocking part as described above, it becomes possible to improve the power generation stability of the fuel cell stack to a greater extent.

[0024] Preferably, in the fuel cell stack, the dummy resin / plastic frame member has the same structure as the resin / plastic frame member. In this case, the same structure can be applied to the dummy resin / plastic frame member and the resin / plastic frame member of the power generation cell. Accordingly, the dummy cell can have a simpler and more cost-effective structure.

[0025] Preferably, in the fuel cell stack, the three electrically conductive porous bodies are made of the same material. In the dummy cell, the dummy assembly is formed by stacking the electrically conductive porous bodies made of the same material. Unlike the dummy cell according to the comparative example, in which elements made of different materials are stacked together, with, for example, the metal plate being held by the electrically conductive porous body, it is possible to reduce the contact resistance. Since it is possible to reduce the internal resistance of the fuel cell stack in the structure, it is possible to improve the power generation efficiency.

[0026] In the fuel cell stack, a connecting part configured to connect the dummy assembly and the dummy resin / plastic frame member is discontinuously formed in a circumferential direction of the dummy assembly. Unlike the power generation cell in which the outer portions of the resin / plastic frame member and the membrane electrode assembly are firmly connected to suppress cross leaks, etc., in the dummy cell that does not perform power generation, there is no need to suppress cross leaks. Therefore, by forming the connecting part at which the dummy assembly and the dummy resin / plastic frame member are discontinuously connected to each other, it becomes possible to simplify the step of connecting the dummy assembly and the dummy resin / plastic frame member and improve the production efficiency of the fuel cell stack.

[0027] Preferably, in the fuel cell stack, the dummy assembly is formed by stacking the three electrically conductive porous bodies comprising a first electrically conductive porous body, a second electrically conductive porous body having an area larger than that of the first electrically conductive porous body, and a third electrically conductive porous body having an area larger than that of the second electrically conductive porous body, and the area of ​​the third electrically conductive porous body is larger than an area of ​​the gas diffusion layer.

[0028] As described above, in the dummy assembly of the dummy cell that does not perform power generation, there is no need to apply a dimensional tolerance as in the case of the membrane electrode assembly of the power generation cell that performs power generation. Furthermore, the dummy resin / plastic frame member provided at the outer end of the dummy assembly has the same structure as the resin / plastic frame member provided at the outer end of the membrane electrode assembly. Therefore, by making the area of ​​the third electrically conductive porous body larger than the area of ​​the gas diffusion layer, it is possible to make the connection area between the dummy assembly and the dummy resin / plastic frame member larger than the connection area between the membrane electrode assembly and the resin / plastic frame member.

[0029] In this way, it is possible to improve the connection strength of the dummy resin / plastic frame member and the dummy assembly. As a result, it is possible to reliably connect the resin / plastic frame member and the dummy assembly to maintain the dummy cell without causing rattling.

[0030] With the above structure, it is possible to obtain a dummy cell in the fuel cell stack that has high quality and a high yield rate. Furthermore, it is possible to improve power generation stability.

[0031] Preferably, in the fuel cell stack, the second electrically conductive porous body is provided at a center of the dummy assembly in the stacking direction, the dummy resin / plastic frame member includes a contact surface configured to contact an outer exposed portion of the second electrically conductive porous body extending outward beyond an outer end face of the first electrically conductive porous body, and a connecting surface connected by a connecting part to an outer exposed portion of the third electrically conductive porous body extending outward beyond an outer end face of the second electrically conductive porous body, and the connecting part is formed discontinuously in a circumferential direction of the outer exposed portion of the third electrically conductive porous body.

[0032] Unlike the power generation cell, in which the outer portions of the resin / plastic frame member and the membrane electrode assembly are hermetically bonded to suppress cross leaks, etc., in the dummy cell that does not perform power generation, it is not necessary to suppress cross leaks. Therefore, by forming the connecting part where the dummy assembly and the dummy resin / plastic frame member are discontinuously bonded, it becomes possible to simplify the step of bonding the dummy assembly and the dummy resin / plastic frame member and improve the production efficiency of the fuel cell stack.

[0033] Preferably, in the fuel cell stack, the connecting part includes an impregnation portion, wherein the outer exposed portion of the third electrically conductive porous body is impregnated with a portion of the molten dummy resin / plastic frame member. In this case, since a portion of the dummy resin / plastic frame member is impregnated into the third electrically conductive porous body, it is possible to improve the joining strength of the dummy resin / plastic frame member and the dummy assembly, for example, unlike the dummy resin / plastic frame member and the dummy assembly that are bonded using adhesive only between the dummy resin / plastic frame member and the dummy assembly.

[0034] In the fuel cell stack, a part of the dummy resin / plastic frame member is a resin / plastic protrusion provided on an outer side beyond the joint surface of the dummy resin / plastic frame member in such a way that the resin / plastic protrusion protrudes in a thickness direction of the resin / plastic frame member. In this case, with the simple structure, it is possible to easily and conveniently form the joint part. This makes it possible to obtain each of the dummy cells more efficiently. Furthermore, it is possible to improve the power generation efficiency of the fuel cell stack.

[0035] Preferably, a water-repellent treatment is applied to one of the three electrically conductive porous bodies in the fuel cell stack. In this case, it is possible to prevent the stagnation of liquid water, such as condensate and / or produced water, within the dummy cell. Therefore, it is possible to prevent the dummy cell from freezing even in low-temperature environments.

[0036] Preferably, in the fuel cell stack, the dummy assembly is formed by stacking the three electrically conductive porous bodies comprising a first electrically conductive porous body, a second electrically conductive porous body stacked on the first electrically conductive porous body, and a third electrically conductive porous body stacked on the second electrically conductive porous body, a water-repellent treatment is applied to one of the second electrically conductive porous body and the third electrically conductive porous body, each of the separators and the dummy separators has a channel for an oxygen-containing gas configured to allow an oxygen-containing gas to flow in the stacking direction of the stacked body, and a channel for a fuel gas configured to allow a fuel gas,to flow in the stacking direction of the stacked body, the separator facing one of the electrodes of the membrane electrode assembly has a flow field for an oxygen-containing gas along which the oxygen-containing gas flows, the separator facing another of the electrodes of the membrane electrode assembly has a flow field for a fuel gas along which the fuel gas flows, a first gap corresponding to the flow field for an oxygen-containing gas is formed between the dummy separator and the first electrically conductive porous body, a second gap corresponding to the flow field for a fuel gas is formed between the dummy separator and the third electrically conductive porous body, a connecting channel is configured to allow a flow of the oxygen-containing gas,provided between the channel for an oxygen-containing gas and the first space, and a blocking part adapted to block a flow of the fuel gas is provided between the channel for a fuel gas and the second space.

[0037] Since the fuel gas does not flow through the second gap, the thermal insulation performance in the second gap is increased, and the second gap acts as a thermal insulation space. Accordingly, the dummy cell can significantly improve the thermal insulation performance. Furthermore, it is possible to reduce the amount of fuel gas discharged from the fuel cell stack without contributing to electrochemical reactions for power generation.

[0038] Furthermore, during the high-load power generation of the fuel cell stack, or when the power generation of the fuel cell stack is stopped and the flow rate of the oxygen-containing gas flowing through the first gap is increased by the drying process, or when each of the dummy cells is dried, the condensate water collected by each of the dummy cells, etc., is smoothly discharged in a liquid state from each of the dummy cells.

[0039] In the dummy assembly, the water-repellent treatment is applied to the third electrically conductive porous body adjacent to the second gap or the second electrically conductive porous body adjacent to the third electrically conductive porous body. Therefore, in the dummy cell, it is possible to prevent liquid water from flowing from the first gap into the second gap, where the flow of fuel gas is blocked as described above.

[0040] As a result, the oxygen-containing gas flowing through the first gap allows the liquid water in each of the dummy cells to be more effectively drained. Accordingly, stagnation of the liquid water in each of the dummy cells can be prevented. This effectively prevents the dummy cell from freezing and further improves the power generation stability of the fuel cell stack.

[0041] Preferably, in the fuel cell stack, a connecting part is discontinuously formed in a circumferential direction of the electrically conductive porous body having the largest surface area among the three electrically conductive porous bodies. This connecting part is configured to connect the dummy assembly and the dummy resin / plastic frame member to each other. In this case, it becomes possible to simplify the step of connecting the dummy assembly and the dummy resin / plastic frame member and improve the production efficiency of the fuel cell stack.

[0042] Preferably, in the fuel cell stack, each of the separators and the dummy separators has a channel for an oxygen-containing gas, which is configured to allow an oxygen-containing gas to flow in the stacking direction of the stacked body, and a channel for a fuel gas, which is configured to allow a fuel gas to flow in the stacking direction of the stacked body. A separator of the separators, which faces one of the electrodes of the membrane electrode assembly, has a flow field for an oxygen-containing gas along which the oxygen-containing gas flows. Another separator of the separators, which faces another of the electrodes of the membrane electrode assembly, has a flow field for a fuel gas along which the fuel gas flows. A first gap, which corresponds to the flow field for an oxygen-containing gas,between a dummy separator of the dummy separators facing one end side of the dummy assembly in the stacking direction and the one end side of the dummy assembly, and a second gap corresponding to the flow field for a fuel gas is formed between another dummy separator of the dummy separators facing another end side of the dummy assembly in the stacking direction and the other end side of the dummy assembly, and a connecting channel configured to allow the flow of the oxygen-containing gas is provided between the channel for an oxygen-containing gas and the first gap, and the dummy assembly has a through hole connecting the first gap and the second gap in the vertical direction at a lower position.

[0043] In the fuel cell stack, the oxygen-containing gas channel and the first gap, which is adjacent to one end of the dummy assembly in the stacking direction, are connected to each other by the connecting channel. Since the oxygen-containing gas flows through the first gap in the structure, even if the oxygen-containing gas contains condensed water, the condensed water is collected by the dummy cell, and it is possible to prevent the condensed water from splashing into the power generation cells.

[0044] Furthermore, since the through-hole is provided in the dummy assembly to connect the first gap and the second gap in the vertical direction at the lower position, even in the case that the liquid water enters the second gap, the liquid water moves toward the through-hole by gravity, and the liquid water is guided toward the first gap through the through-hole.

[0045] This makes it possible to more effectively drain water from the dummy cells through the oxygen-containing gas flowing through the first gap, and it is possible to suppress the stagnation of liquid water within the dummy cell. Therefore, it is possible to prevent freezing of the dummy cell even in a low-temperature environment. As described above, in the fuel cell stack, it is possible to improve the stability of power generation by preventing freezing of the dummy cell.

[0046] Preferably, in the fuel cell stack, the through-hole of the dummy assembly is provided on an outlet side of the oxygen-containing gas flowing through the first space, adjacent to the oxygen-containing gas channel. With this structure, it is possible to effectively discharge the liquid water flowing from the second space to the first space through the through-hole to the outside of the dummy cell (the oxygen-containing gas channel on the outlet side).

[0047] Preferably, in the fuel cell stack, the separators and the dummy separators have a rectangular shape and the longitudinal direction of the rectangular shape is oriented in a horizontal direction, the oxygen-containing gas channel on an inlet side, which is configured to supply the oxygen-containing gas to the oxygen-containing gas flow field and the first gap, is provided at an upper position in the vertical direction of the separators and the dummy separators, and the oxygen-containing gas channel on an outlet side, which is configured to discharge the oxygen-containing gas from the flow field and the first gap, is provided at a lower position in the vertical direction of the separators and the dummy separators.In the structure, by effectively guiding the liquid water in the dummy cell by gravity to the channel for an oxygen-containing gas on the outlet side, it becomes possible to discharge water in an appropriate manner.

[0048] Preferably, in the fuel cell stack, the first gap is configured to allow the oxygen-containing gas to flow in a direction aligned with a longitudinal direction of the dummy separators. In this case, it is possible to easily guide the liquid water in the dummy cell toward the oxygen-containing gas channel on the outlet side through the first gap to discharge the water.

[0049] Preferably, in the fuel cell stack, the three electrically conductive porous bodies comprise a first electrically conductive porous body, a second electrically conductive porous body having an area larger than that of the first electrically conductive porous body, and a third electrically conductive porous body having an area larger than that of the second electrically conductive porous body, and the dummy resin / plastic frame member comprises an outer edge portion, a shoulder protruding inward from an inner end of the outer edge portion over an entire circumference through a first stepped surface, and a thin portion protruding inward from an inner end of the shoulder over an entire circumference through a second stepped surface,an outer edge portion of the third electrically conductive porous body overlaps the shoulder of the dummy resin / plastic frame member, and an outer edge portion of the second electrically conductive porous body is adjacent to the thin portion of the dummy resin / plastic frame member, and an outer end surface of the first electrically conductive porous body faces an inner end surface of the dummy resin / plastic frame member.

[0050] Preferably, in the fuel cell stack, the thickness of the second electrically conductive porous body is greater than the height of the second stepped surface.

[0051] Preferably, a gap is formed in the fuel cell stack between the thin portion of the dummy resin / plastic frame member and the third electrically conductive porous body.

[0052] According to another aspect of the present invention, a dummy cell for a fuel cell stack according to claim 20 is provided.

[0053] In the dummy cell for a fuel cell stack, with the simple structure having the dummy assembly formed by stacking three electrically conductive porous bodies, it is possible to suppress the influence of the outside air temperature on the fuel cell stack and improve the stability of power generation.

[0054] According to yet another aspect of the present invention, there is provided a method of manufacturing a dummy cell according to claim 21.

[0055] In the process for manufacturing the dummy cell, a water-repellent treatment is applied to one of the three electrically conductive porous bodies of the dummy assembly. As a result, it is possible to obtain the dummy cell in which stagnation of liquid water, such as condensate and generated water, is suppressed. Since power generation is not performed in the dummy cell, no water is generated. The dummy cell therefore acts as a thermal insulation layer. Since it is possible to increase the thermal insulation performance at the end of the stacked body To improve the stability of power generation, it is possible to improve the stability of power generation in the fuel cell having the dummy cell provided at least at one end of the stack body in the stacking direction. Therefore, by using the dummy cell in which freezing is suppressed, it is possible to improve the power generation stability of the fuel cell stack even in a low-temperature environment.

[0056] The above and other object features and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an exploded perspective view illustrating a fuel cell stack according to an embodiment of the present invention; Fig. 2 is a cross-sectional view of a fuel cell stack taken along a line II-II in Fig. 1; Fig. 3 is an exploded perspective view showing a power generation cell; Fig. 4 is a front view showing a flow field for an oxygen-containing gas of a first separator; Fig. 5 is a front view showing a flow field for an oxygen-containing gas of a second separator; Fig. 6 is a front view illustrating a coolant flow field of a third separator; Fig. 7 is a front view showing an anode of an MEA equipped with a resin / plastic frame; Fig. 8 is a cross-sectional view taken along the line VIII-VIII in Fig. 7; Fig. 9 is a front view showing a third electrically conductive porous body of a dummy assembly equipped with a resin / plastic frame; Fig. 10 is a cross-sectional view taken along a line XX in Fig. 9; Fig. 11 is an exploded perspective view showing a dummy assembly; Fig. 12 is a front view illustrating a second gap of a second dummy separator and a third dummy separator; Fig. 13 is a front view showing a third electrically conductive porous body of a resin frame-equipped dummy assembly according to a modified embodiment; Fig. 14 is an exploded perspective view showing a dummy assembly of Fig. 13 shows. DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0057] A preferred embodiment of a method for manufacturing a fuel cell stack, a dummy cell for a fuel cell stack, and a dummy cell according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, components having the same or similar functions and having the same or similar advantages are denoted by the same reference numerals, and the description of these components will be omitted as necessary.

[0058] As in the Fig. 1 and Fig. As shown in Figure 2, the fuel cell stack 10 according to an embodiment of the present invention includes a stacked body 14 formed by stacking a plurality of power generation cells 12 in the horizontal direction (indicated by arrows A1 and A2) or in the direction of gravity (indicated by arrows C1 and C2). For example, the fuel cell stack 10 is mounted in a fuel cell vehicle, such as a fuel cell electric car (not shown).

[0059] As in Fig. 2, a first end power generation unit 16 is provided at one end of the stacked body 14 in a stacking direction of the stacked body 14 (indicated by an arrow A1). A first dummy cell 18 is provided outside the first end power generation unit 16, and a second dummy cell 20 is provided outside the first dummy cell 18. Further, a second end power generation unit 22 is provided at the other end of the stacked body 14 in the stacking direction indicated by arrow A2. A third dummy cell 24 is provided outside the second end power generation unit 22. A terminal plate 26a is provided outside the second dummy cell 20 of the stacked body 14 in the direction indicated by arrow A1, and an insulator 28a is provided outside the terminal plate 26a, and an end plate 30a is provided outside the insulator 28a.A terminal plate 26b is provided outside the third dummy cell 24 of the stacked body 14 in the direction indicated by an arrow A2. An insulator 28b is provided outside the terminal plate 26b, and an end plate 30b is provided outside the insulator 28b.

[0060] As in Fig. 1, coupling rods (not shown) are provided between sides of the rectangular end plates 30a, 30b. Both ends of each of the coupling rods are fixed to inner surfaces of the end plates 30a, 30b using bolts (not shown) to exert a tightening force on a plurality of power generation cells 12 in the stacking direction indicated by arrows A1, A2. The fuel cell stack 10 may include a casing having the end plates 30a, 30b, and the stack body 14, etc., may be placed in the casing.

[0061] As in Fig. 3, the power generation cell 12 includes a first separator 32, a resin / plastic frame-equipped MEA 34 stacked on the first separator 32, a second separator 36 stacked on the resin / plastic frame-equipped MEA 34, a resin / plastic frame-equipped MEA 34 stacked on the second separator 36, and a third separator 38 stacked on the resin / plastic frame-equipped MEA 34. Each of the first separator 32, the second separator 36, and the third separator 38 (each of the separators) is in the form of a steel plate, a stainless steel plate, an aluminum plate, a coated steel plate, and is formed by press forming, etc., to have a rectangular shape in a plan view and a corrugated / ribbed shape in a cross section.

[0062] As in the Fig. 1 and Fig. As shown in Figure 3, at one end of each separator in the longitudinal direction (long side direction) (horizontal direction) indicated by an arrow B1, there are provided an oxygen-containing gas supply channel 40 (oxygen-containing gas channel) and a fuel gas discharge channel 42 (fuel gas channel). The oxygen-containing gas supply channel 40 and the fuel gas discharge channel 42 extend through each separator in the stacking direction indicated by arrows A1 and A2, respectively. An oxygen-containing gas is supplied through the oxygen-containing gas supply channel 40. A fuel gas is discharged through the fuel gas discharge channel 42. These oxygen-containing gas and fuel gas are collectively referred to as the reaction gases.

[0063] At the other end of each separator in the longitudinal direction (long side direction), indicated by an arrow B2, a fuel gas supply channel 44 (fuel gas channel) for supplying the fuel gas and an oxygen-containing gas discharge channel 46 (oxygen-containing gas channel) for discharging the oxygen-containing gas are provided. The fuel gas supply channel 44 and the oxygen-containing gas discharge channel 46 extend through each separator in the stacking direction, indicated by arrows A1, A2. The oxygen-containing gas supply channel 40, the fuel gas discharge channel 42, the fuel gas supply channel 44, and the oxygen-containing gas discharge channel 46 are collectively referred to as the reaction gas channel.

[0064] The oxygen-containing gas supply channel 40 and the fuel gas supply channel 44 are provided at upper positions of each separator in the vertical direction indicated by an arrow C1, and the fuel gas discharge channel 42 and the oxygen-containing gas discharge channel 46 are provided at lower positions of each separator in the vertical direction indicated by an arrow C2. The vertical direction here is the vertical direction during operation of the fuel cell stack 10.

[0065] At both ends in the transverse direction (short side direction) of each separator (vertical direction indicated by arrows C1, C2), on the side indicated by arrow B1, a pair of coolant supply channels 48 for supplying a coolant are provided. The coolant supply channels 48 extend through each separator in the direction indicated by arrows A1, A2. At both ends in the transverse direction (short side direction) of each separator, on the side indicated by arrow B2, a pair of coolant discharge channels 50 for discharging the coolant are provided. The coolant discharge channels 50 extend through each separator in the direction indicated by arrows A1, A2.

[0066] As in Fig. As shown in Figure 3, on a surface 32a of the first separator 32 oriented in the direction indicated by arrow A1, a coolant flow field 52 is formed to communicate between the coolant supply channels 48 and the coolant discharge channels 50. A plurality of inlet communication grooves 54a are formed between the coolant supply channels 48 and the coolant flow field 52. A plurality of outlet communication grooves 54b are formed between the coolant flow field 52 and the coolant discharge channels 50. Further, on the surface 32a of the first separator 32, a sealing member 55 is provided around the coolant supply channels 48, the coolant discharge channels 50, the coolant flow field 52, the inlet connection grooves 54a and the outlet connection grooves 54b, and provides a seal between the inside and the outside of the sealing member 55 in the surface direction.

[0067] As in Fig. As shown in Figure 4, the first separator 32 has a flow field 56 for an oxygen-containing gas on its surface 32b, oriented in the direction indicated by arrow A2. The oxygen-containing gas flow field 56 is connected to the oxygen-containing gas supply channel 40 and the oxygen-containing gas discharge channel 46. The oxygen-containing gas flow field 56 includes a plurality of parallel wave-like flow grooves (or straight flow grooves).

[0068] An oxygen-containing gas inlet buffer 58 is connected to an inlet end of the oxygen-containing gas flow field 56 at a position outside the power generation region, and an oxygen-containing gas outlet buffer 60 is connected to an outlet end of the oxygen-containing gas flow field 56 at a position outside the power generation region.

[0069] A plurality of inlet connection grooves 62a are formed between the oxygen-containing gas inlet buffer 58 and the oxygen-containing gas supply channel 40. A plurality of outlet connection grooves 62b are formed between the oxygen-containing gas outlet buffer 60 and the oxygen-containing gas discharge channel 46. Furthermore, on the surface 32b of the first separator 32, around the oxygen-containing gas supply channel 40, the oxygen-containing gas discharge channel 46, the oxygen-containing gas flow field 56, the oxygen-containing gas inlet buffer 58, the oxygen-containing gas outlet buffer 60, the inlet connection grooves 62a and the outlet connection grooves 62b, a sealing member 63 is provided, which provides a seal between the inside and the outside of the sealing member 63 in the surface direction.In the first separator 32, the back side of the flow field 56 for an oxygen-containing gas forms part of the coolant flow field 52 (see . Fig. 2 and Fig. 3).

[0070] As in Fig. 3, the second separator 36 has a fuel gas flow field 66 on its surface 36a, which is oriented in the direction indicated by arrow A1. The fuel gas flow field 66 is connected to the fuel gas supply channel 44 and the fuel gas discharge channel 42. The fuel gas flow field 66 includes a plurality of wave-like flow grooves (or straight flow grooves) arranged in parallel. In the embodiment of the present invention, each of the oxygen-containing gas flow field 56 and the fuel gas flow field 66 includes straight flow grooves rather than serpentine flow grooves.

[0071] Outside the power generation region, a fuel gas inlet buffer 68 is connected to the inlet end of the fuel gas flow field 66, and outside the power generation region, a fuel gas outlet buffer 70 is connected to the outlet end of the fuel gas flow field 66.

[0072] A plurality of fuel gas supply holes 72a are provided between the fuel gas inlet buffer 68 and the fuel gas supply channel 44. The supply holes 72a penetrate the second separator 36 in the thickness direction. The fuel gas flowing through the fuel gas supply channel 44 from arrow A1 to arrow A2 flows through the fuel gas supply holes 72a from arrow A2 to arrow A1 and then flows into the fuel gas inlet buffer 68.

[0073] A plurality of fuel gas discharge holes 72b are formed between the fuel gas outlet buffer 70 and the fuel gas discharge channel 42. The fuel gas discharge holes 72b penetrate the second separator 36 in the thickness direction. The fuel gas that has flowed into the fuel gas outlet buffer 70 along the fuel gas flow field 66 flows through the fuel gas discharge holes 72b from arrow A1 to arrow A2 and flows along the fuel gas discharge channel 42 from arrow A2 to arrow A1.

[0074] A sealing member 73 is provided on the surface 36a of the second separator 36 around the fuel gas flow field 66, the fuel gas inlet buffer 68, the fuel gas outlet buffer 70, the fuel gas supply holes 72a, and the fuel gas discharge holes 72b, and provides sealing between the inside and outside of the sealing member 73 in the surface direction.

[0075] As in Fig. 5, the surface 36b of the second separator 36 oriented in the direction of arrow A2 has the same structure as the surface 32b of the first separator 32 (see Fig. 4), indicated by arrow A2, except that fuel gas supply holes 72a and fuel gas discharge holes 72b surrounded by the sealing member 71 are provided. That is, the oxygen-containing gas flow field 56 is formed on the surface 36b of the second separator 36. The oxygen-containing gas flow field 56 is connected to the oxygen-containing gas supply channel 40 and the oxygen-containing gas discharge channel 46. Further, an oxygen-containing gas inlet buffer 58, an oxygen-containing gas outlet buffer 60, inlet communication grooves 62a, outlet communication grooves 62b, and a sealing member 63 are formed on the surface 36b of the second separator 36.

[0076] On the surface 36b of the second separator 36, the fuel gas supply holes 72a and the fuel gas discharge holes 72b are separated from the oxygen-containing gas inlet buffer 58 and the oxygen-containing gas outlet buffer 60 by the sealing members 63, 71.

[0077] As in Fig. 3, the surface 38a of the third separator 38, which is oriented in the direction of arrow A1, has the same structure as the surface 36a of the second separator 36, which is oriented in the direction of arrow A1. That is, the fuel gas flow field 66 is formed on the surface 38a of the third separator 38. The fuel gas flow field 66 is connected to the fuel gas supply channel 44 and the fuel gas discharge channel 42. Furthermore, the fuel gas inlet buffer 68, the fuel gas outlet buffer 70, the fuel gas supply holes 72a, the fuel gas discharge holes 72b, and the sealing member 73 are formed on the surface 38a of the third separator 38.

[0078] As in Fig. 6, the surface 38b of the third separator 38, which is oriented in the direction of arrow A2, has the same structure as the surface 32a of the first separator 32, which is oriented in the direction indicated by the arrow A1 (see Fig. 3), except that the fuel gas supply holes 72a and the fuel gas discharge holes 72b, which are surrounded by the sealing member 71, are provided. That is, the coolant flow field 52, the inlet communication grooves 54a, the outlet communication grooves 54b, and the sealing member 55 are provided on the surface 38b of the third separator 38. On the surface 38b of the third separator 38, each of the fuel gas supply holes 72a and the fuel gas discharge holes 72b is separated from the coolant flow field 52, the inlet communication grooves 54a, the outlet communication grooves 54b, etc., by the sealing members 55, 71.

[0079] As in Fig. 2, the coolant can flow between the coolant flow field 52 at the surface 38b of the third separator 38, which is oriented in the direction indicated by arrow A2, and the coolant flow field 52 at the surface 32a of the first separator 32, which is oriented in the direction indicated by arrow A1, which are adjacent to each other.

[0080] A sealing member (not shown) is integrally formed with each of the two surfaces of the separator. The sealing member is made of an elastic material and is provided around the outer end of each separator.

[0081] As in Fig. 3, Fig. 7 and Fig. 8, the resin-framed MEA 34 is formed by bonding a resin-frame member 82 to the outer end of the membrane electrode assembly (MEA) 80. As shown in Fig. As shown in Figure 8, the membrane electrode assembly 80 includes a solid polymer electrolyte membrane (hereinafter also simply referred to as the electrolyte membrane) 84, which is, for example, a thin membrane of perfluorosulfonic acid containing water. A fluorine-based electrolyte can be used as the electrolyte membrane 84. Alternatively, an HC (hydrocarbon)-based electrolyte can be used as the electrolyte membrane 84. The electrolyte membrane 84 is sandwiched between a cathode 86 and an anode 88.

[0082] The membrane electrode assembly 80 is an MEA that includes components of different sizes, with the surface area of ​​the cathode 86 being smaller than the surface areas of the anode 88 and the electrolyte membrane 84. The cathode 86, the anode 88, and the electrolyte membrane 84 may have the same surface area. Alternatively, the surface area of ​​the anode 88 may be smaller than the surface areas of the cathode 86 and the electrolyte membrane 84.

[0083] The cathode 86 includes a first electrode catalyst layer 90 bonded to an end surface 84a of the electrolyte membrane 84 (indicated by arrow A1) and a first gas diffusion layer 92 stacked on the first electrode catalyst layer 90. The surface area of ​​the first electrode catalyst layer 90 is larger than the surface area of ​​the first gas diffusion layer 92 and includes an outer exposed portion 90a protruding outward from an outer end surface 92a of the first gas diffusion layer 92. The surface area of ​​the first electrode catalyst layer 90 is smaller than the surface area of ​​the electrolyte membrane 84.

[0084] The anode 88 includes a second electrode catalyst layer 94 bonded to the other end surface 84b of the electrolyte membrane 84 (indicated by arrow A2) and a second gas diffusion layer 96 stacked on the second electrode catalyst layer 94. The second electrode catalyst layer 94 and the second gas diffusion layer 96 have the same surface area, which is equal to (or less than) the surface area of ​​the electrolyte membrane 84.

[0085] For example, the first electrode catalyst layer 90 is formed by porous carbon particles evenly deposited on the surface of the first gas diffusion layer 92, along with an ion-conductive polymer binder and a platinum alloy supported on the porous carbon particles. For example, the second electrode catalyst layer 94 is formed by porous carbon particles evenly deposited on the surface of the second gas diffusion layer 96, along with an ion-conductive polymer binder and a platinum alloy supported on the porous carbon particles.

[0086] The first gas diffusion layer 92 and the second gas diffusion layer 96 are made of an electrically conductive porous body such as carbon paper or carbon cloth, etc. The surface area of ​​the second gas diffusion layer 96 is larger than the surface area of ​​the first gas diffusion layer 92. It should be noted that a water-repellent treatment may be applied to the electrically conductive porous material of the first gas diffusion layer 92 and the second gas diffusion layer 96 to include a water-repellent resin such as a tetrafluoroethylene-hexafluoropropylene copolymer (FEP). As shown in Fig. 7, the length of the long side of the second gas diffusion layer 96 is X1 and the length of the short side of the second gas diffusion layer 96 is X2.

[0087] For example, the resin / plastic frame member 82 is made of a resin / plastic material such as PPS (polyphenylene sulfide), PPA (polyphthalamide), PEN (polyethylene naphthalate), PES (polyethersulfone), LCP (liquid crystal polymer), PVDF (polyvinylidene fluoride), a silicone resin / plastic, a fluorine resin / plastic, m-PPE (modified polyphenylene ether) resin / plastic, PET (polyethylene terephthalate), PBT (polybutylene terephthalate), or a modified polyolefin. Note that the resin / plastic material may be made of a film having a constant thickness, etc.

[0088] As in Fig. 3, the resin / plastic frame member 82 has a frame shape, and the resin / plastic frame member 82 is provided within a group of fluid channels 40, 42, 44, 46, 48, 50, which include the supply channel 40 for an oxygen-containing gas. The fluid channels 40, 42, 44, 46, 48, 50 are not formed in the resin / plastic frame member 82. As shown in Fig. 7, the resin / plastic frame member 82 further includes an outer edge portion 82b over the predetermined length inside the outer end 82a (see Fig. 7) and an inner extension 82c within the outer edge portion 82b.

[0089] The inner extension 82c includes a step 82e extending from the inner end of the outer edge portion 82b through a first stepped surface 82d, and a thin portion 82g extending from the inner end of the step 82e through a second stepped surface 82f. The step 82e is thinner than the outer edge portion 82b, and the thin portion 82g is thinner than the step 82e. Further, the first stepped surface 82d, the step 82e, the second stepped surface 82f, and the thin portion 82g are provided over the entire circumference of the resin / plastic frame member 82. The outer edge portion of the surface 84a of the electrolyte membrane 84 contacts the surface 82ea of ​​the step 82e, which is oriented in the direction indicated by the arrow A2.At the inner end of the thin portion 82g, a protrusion 82h is provided over the entire circumference, which faces the outer exposed portion 90a of the first electrode catalyst layer 90. Further, a groove 82ha is provided between the protrusion 82h and the second stepped surface 82f.

[0090] As in Fig. As shown in Fig. 7, the distance between the first stepped surfaces 82d provided at both ends of the resin frame member 82 in the longitudinal direction (long side direction) (indicated by arrows B1 and B2) is Y1, and the distance between the first stepped surfaces 82d provided at both ends of the resin frame member 82 in the transverse direction (short side direction) indicated by arrows C1 and C2 is Y2. The first stepped surfaces 82d of the four sides of the resin frame member 82 and the outer end surface 101 of the four sides of the electrolyte membrane 84 and the anode 88 are spaced from each other by the distance L1. That is, the interval between the first stepped surface 82d and the outer end surface 101 is the same distance L1 over the entire circumference.

[0091] Adhesive 98a is filled on the surface 84a of the electrolyte membrane 84 facing the groove 82ha and the outer exposed portion 90a of the first electrode catalyst layer 90, around the outer exposed portion 90a to form an adhesive portion 98. Further, the adhesive 98a of this adhesive portion 98 is filled between an inner end surface 82i of the resin / plastic frame member 82 and the outer end surface 92a of the first gas diffusion layer 92. As the adhesive 98a, for example, fluorocarbon resin / plastic, silicone resin / plastic, epoxy resin / plastic, etc. can be suitably used. However, the present invention is not limited in this respect. The adhesive 98a is not limited to a liquid or solid state adhesive, a thermoplastic resin / plastic, a thermosetting resin / plastic, etc.

[0092] The resin / plastic frame member 82 and the outer edge portion of the second gas diffusion layer 96 are joined together by a first joining part 100 using an adhesive resin / plastic. As shown in Fig. 7, the first connecting part 100 is provided around the outer end of the second gas diffusion layer 96. As shown in Fig. As shown in FIG. 8, the first connecting part 100 is formed, for example, by thermally deforming a resin / plastic protrusion 100a, which is integrally formed with the resin / plastic frame member 82, in such a manner that the resin / plastic protrusion 100a is provided around the inner end of the outer edge portion 82b and protrudes in the direction indicated by arrow A2. The first connecting part 100 includes a first resin / plastic impregnation portion 100b and a first melted and solidified portion 100c.

[0093] The first resin / plastic impregnation portion 100b is formed by impregnating the outer edge portion of the second gas diffusion layer 96 with molten resin / plastic of the resin / plastic protrusion 100a. In the state where the first stepped surface 82d of the resin / plastic frame member 82 is spaced from the outer end surface 101 of the electrolyte membrane 84 and the anode 88 by the distance L1, the molten resin / plastic protrusion 100a is supplied between the first stepped surface 82d of the resin / plastic frame member 82 and the outer end surface 101 of the electrolyte membrane 84 and the anode 88 and solidified therebetween to form the first molten and solidified portion 100c. Fig. 8, the surface of the shoulder 82e and the first stepped surface 82d are formed integrally with the first melted and solidified portion 100c and indicated by a two-dot chain line.

[0094] The adhesive portion 98 is provided around the outer exposed portion 90a of the first electrode catalyst layer 90 and the outer end surface 92a of the first gas diffusion layer 92. The first connecting part 100 is provided around the outer edge portion of the second gas diffusion layer 96 to prevent cross leakage between the cathode 86 and the anode 88.

[0095] As in Fig. 3, an oxygen-containing gas inlet buffer 102a and an oxygen-containing gas outlet buffer 102b are provided on the surface 82j of the resin / plastic frame member 82 facing the cathode 86 (oriented in the direction indicated by arrow A1). As shown in Fig. 7, an inlet buffer 104a for a fuel gas and an outlet buffer 104b for a fuel gas are provided on the surface 82k of the resin / plastic frame member 82 facing the anode 88 (oriented in the direction indicated by the arrow A2).

[0096] As in Fig. 2, the first final power generation unit 16 is formed by stacking a first dummy separator 105, a resin-framed dummy assembly 106 on the first dummy separator 105, a second dummy separator 108 on the resin-framed dummy assembly 106, the resin-framed MEA 34 on the second dummy separator 108, and the third separator 38 on the resin-framed MEA 34, from the side indicated by the arrow A1 to the side indicated by the arrow A2.

[0097] As in Fig. As shown in FIGS. 2 to 4, the first dummy separator 105 has the same structure as the first separator 32. The coolant flow field 52 is provided on a surface 105a of the first dummy separator 105 at one end (indicated by arrow A1). A first gap 109, which corresponds to the oxygen-containing gas flow field 56, is provided between the surface 105b of the first dummy separator 105 at the other end (indicated by arrow A2) and one end side of the resin-framed dummy assembly 106 (indicated by arrow A1). The first space 109 is connected to the supply channel 40 for an oxygen-containing gas and the discharge channel 46 for an oxygen-containing gas through a connecting channel 125 formed within the inlet connecting grooves 62a and the outlet connecting grooves 62b.Therefore, the oxygen-containing gas can flow through the first gap 109, similar to the flow field 56 for an oxygen-containing gas.

[0098] As in Fig. 9 and Fig. 10, the resin / plastic frame-equipped dummy assembly 106 is formed by connecting a dummy resin / plastic frame member 111 to the outer end of a dummy assembly 110. As shown in Fig. 10 and Fig. 11, the dummy assembly 110 is formed by stacking three electrically conductive porous bodies having different surface areas (external dimensions) together to comprise, from arrow A1 to arrow A2, a first electrically conductive porous body 112, a second electrically conductive porous body 114 stacked on the first electrically conductive porous body 112, and a third electrically conductive porous body 116 stacked on the second electrically conductive porous body 114.

[0099] With regard to the area size, the following relationship is established: First electrically conductive porous body 112 < Second electrically conductive porous body 114 < Third electrically conductive porous body 116. As in Fig. Therefore, as shown in Figure 10, an outer exposed portion 116a is provided in the outer peripheral portion of the third electrically conductive porous body 116. The outer exposed portion 116a protrudes outward over the entire circumference beyond the outer end surface 114a of the second electrically conductive porous body 114. An outer exposed portion 114b is provided in the outer peripheral portion of the second electrically conductive porous body 114. The outer exposed portion 114b protrudes outward over the entire circumference beyond the outer end surface 112a of the first electrically conductive porous body 112.

[0100] In the dummy assembly 110, the surface area of ​​the third electrically conductive porous body 116, which has the largest surface area, is larger than the surface area of ​​the second gas diffusion layer 96. As shown in Fig. As shown in Figure 9, the length of the long side of the third electrically conductive porous body 116 is Z1, and the length of the short side of the third electrically conductive porous body 116 is Z2. Therefore, the following relationship exists between Z1 and Z2, the long side length X1, and the short side length X2 of the second gas diffusion layer 96, namely, Z1>X1 and Z2>X2. The first stepped surface 82d of the four sides of the dummy resin frame member 111 and an outer end surface 116b of the four sides of the third electrically conductive porous body 116 are spaced apart from each other by the distance L2. That is, the interval between the first stepped surface 82d and the outer end surface 116b is the distance L2 over the entire circumference.

[0101] In the dummy assembly 110, the above water-repellent treatment may be applied to the second electrically conductive porous body 114 or the third electrically conductive porous body 116. Except for this water-repellent treatment, the first electrically conductive porous body 112, the second electrically conductive porous body 114, and the third electrically conductive porous body 116 are made of the same material and may be made of the same material as the electrically conductive porous body of the first gas diffusion layer 92 or the second gas diffusion layer 96.

[0102] Furthermore, in the embodiment of the present invention, the first electrically conductive porous body 112, the second electrically conductive porous body 114, and the third electrically conductive porous body 116 have the same thickness as the electrically conductive porous body of the second gas diffusion layer 96. Therefore, by adjusting the surface area of ​​the electrically conductive porous bodies as described above, it is possible to obtain a dummy assembly 110 more easily.

[0103] As in Fig. As shown in Figure 10, the stacked first electrically conductive porous body 112 and the second electrically conductive porous body 114 are bonded together by an adhesive layer 118a, and the second electrically conductive porous body 114 and the third electrically conductive porous body 116 are bonded together by an adhesive layer 118b. As in the case of the adhesive portion 98, the adhesive layers 118a, 118b may use the adhesive 98a.

[0104] As in Fig. 9 and Fig. 10, the dummy resin / plastic frame member 111 has the same structure as the resin / plastic frame member 82 of the resin / plastic frame member-equipped MEA34 in Fig. 7 and Fig. 8 and includes the outer edge portion 82b and the inner extension 82c. As in Fig. As shown in FIG. 10, an outer exposed portion 116a of the third electrically conductive porous body 116 on the side indicated by arrow A1 contacts a recess 82e of the inner extension 82c. A part of the outer exposed portion 116a of the third electrically conductive porous body 116 on the side indicated by arrow A1 and the outer exposed portion 114b of the second electrically conductive porous body 114 on the side indicated by arrow A1 are provided adjacent to the groove 82ha. The outer exposed portion 114b of the second electrically conductive porous body 114 on the side indicated by arrow A1 contacts a projecting end surface 82hb (contact surface) of the protrusion 82h.

[0105] In the direction indicated by arrows A1 and A2, the outer end surface 114a of the second electrically conductive porous body 114 is provided between the third electrically conductive porous body 116 and the groove 82ha. The inner end surface 82i of the dummy resin frame member 111 is positioned in a direction perpendicular to the stacking direction (arrows A1, A2) between the outer end surface 114a of the second electrically conductive porous body 114 and the outer end surface 112a of the first electrically conductive porous body 112. The outer end surface 112a of the first electrically conductive porous body 112 faces the inner end surface 82i of the dummy resin frame member 111 at an interval. The height of the second stepped surface 82f is lower than the thickness of the second electrically conductive porous body 114.

[0106] In the dummy assembly 110, the outer exposed portion 116a of the third electrically conductive porous body 116, which has the largest area, and the surface 82ea (joining surface) of the shoulder 82e of the dummy resin / plastic frame member 111 on the side indicated by the arrow A2 are connected to each other by a second connecting part 120 (connecting part) to form the resin / plastic frame-equipped dummy assembly 106. As shown in Fig. As shown in FIG. 9, the second connecting part 120 is provided discontinuously (in a dot pattern) in the circumferential direction in the outer peripheral region of the third electrically conductive porous body 116. Note that the second connecting part 120 may be formed continuously around the dummy assembly 110.

[0107] As in Fig. As shown in FIG. 10, the second connecting part 120 may be formed by thermally deforming a portion of a resin / plastic protrusion 120a integrally formed with the dummy resin / plastic frame member 111. In this case, the second connecting part 120 includes a second resin / plastic impregnation portion 120b and a second melted and solidified portion 120c. Note that a portion of the resin / plastic protrusion 120a that does not constitute the second connecting part 120, that is, the remaining portion of the resin / plastic protrusion that has not been thermally deformed, may be removed by adjustment, etc.

[0108] The second resin / plastic impregnation portion 120b is formed by impregnating an outer peripheral portion of the third electrically conductive porous body 116 with a molten resin / plastic of the resin / plastic protrusion 120a. In the state in which the first stepped surface 82d of the dummy resin / plastic frame member 111 is spaced from the outer end surface 116b of the third electrically conductive porous body 116 by the distance L2, the second melted and solidified portion 120c is formed by supplying and solidifying molten resin / plastic of the resin / plastic projection 120a between the first stepped surface 82d of the dummy resin / plastic frame member 111 and the outer end surface 116b of the third electrically conductive porous body 116. Fig. In FIG. 10, the surface of the shoulder 82e and the first stepped surface 82d, which are integrally formed with the second melted and solidified portion 120c, are indicated by a two-dot chain line. As in the case of the adhesive portion 98, the adhesive 98a can be used for the first connecting part 100 and the second connecting part 120.

[0109] As described above, the lengths X1, X2 of the second gas diffusion layer 96 are smaller than the lengths Z1, Z2 of the third electrically conductive porous body 116. Therefore, as shown in Fig. 7 and Fig. 9, the intermediate distance L1 as the difference between the distances Y1, Y2 between the first stepped surfaces 82d of the resin / plastic frame member 82 and the lengths X1, X2 of the second gas diffusion layer 96 is larger than the intermediate distance L2 as the difference between the distances Y1 and Y2 between the first stepped surfaces 82d and the lengths Z1, Z2 of the third electrically conductive porous body 116 (L1 > L2).

[0110] As in Fig. 2, Fig. 3 and Fig. 12, the second dummy separator 108 has the same structure as the second separator 36, except that an inlet blocking part 122a is provided instead of the supply holes 72a for a fuel gas, and an outlet blocking part 122b is provided instead of the discharge holes 72b for a fuel gas. That is, the surface 108b of the other end of the second dummy separator 108 (oriented in the direction indicated by the arrow A2) has the same structure as the surface 32b at the other end of the first separator 32, which in Fig. 4 (which is oriented in the direction indicated by arrow A2).

[0111] As in Fig. 2 and Fig. 4, a flow field 56 for an oxygen-containing gas is formed between the surface 108b at the other end of the second dummy separator 108 (oriented in the direction indicated by arrow A2) and the cathode 86 of the resin / plastic frame-equipped MEA 34 (oriented in the direction indicated by arrow A1).

[0112] As in Fig. 2 and Fig. As shown in Figure 12, a second space 126, corresponding to the fuel gas flow field 66, is provided between the surface 108a at one end of the second dummy separator 108 (oriented in the direction indicated by arrow A1) and the other end of the resin-framed dummy assembly 106 (closer to the third electrically conductive porous body 116, oriented in the direction indicated by arrow A2). The second space 126 is separated from the fuel gas supply channel 44 by the inlet blocking portion 122a, and the second space 126 is separated from the fuel gas discharge channel 42 by the outlet blocking portion 122b.Since the flow of the fuel gas in the second space 126 is limited by the inlet blocking part 122a and the outlet blocking part 122b (also collectively referred to as the blocking part), a heat insulating space is formed within the second space 126.

[0113] Only one of the inlet blocking part 122a and the outlet blocking part 122b may be provided to restrict the flow of the fuel gas in the second gap 126 and to form the heat insulating space. Furthermore, the blocking part may be formed by, for example, previously forming the supply holes 72a for a fuel gas and the discharge holes 72b for a fuel gas that do not pass through the second dummy separator 108 (see Fig. 3) or the fuel gas supply holes 72a and the fuel gas discharge holes 72b passing through the second dummy separator 108 are formed, and then the fuel gas supply holes 72a and the fuel gas discharge holes 72b are sealed. Furthermore, on the surface 108a of the second dummy separator 108, a sealing member 127 is provided around the second gap 126 to provide a seal between the inside and outside of the sealing member 127 in the surface direction.

[0114] As described above, in the dummy assembly 110 (the resin frame-equipped dummy assembly 106) sandwiched between the first dummy separator 105 and the second dummy separator 108, the first gap 109 is provided adjacent to the first electrically conductive porous body 112, and the second gap 126 is provided adjacent to the third electrically conductive porous body 116.

[0115] As in Fig. 2, the first dummy cell 18 includes, from the side indicated by arrow A1 to the side indicated by arrow A2, a first dummy separator 105 (dummy separator), a resin-framed dummy assembly 106 stacked on the first dummy separator 105, a second dummy separator 108 (dummy separator) stacked on the resin-framed dummy assembly 106, a resin-framed dummy assembly 106 stacked on the second dummy separator 108, and a third separator 130 (dummy separator) stacked on the resin-framed dummy assembly 106.

[0116] As in Fig. 2, Fig. 3 and Fig. As shown in Figure 6, the surface 130b at the other end of the third dummy separator 130 (indicated by arrow A2) has the same structure as the surface 38b of the third separator 38, which is oriented in the direction indicated by arrow A2, except that the fuel gas supply holes 72a and the fuel gas discharge holes 72b surrounded by the sealing member 71 are not provided. In other words, the surface 130b of the third dummy separator 130 has the same structure as the surface 32a of the first separator 32 at one end (oriented in the direction indicated by arrow A1). Further, as shown in Fig. 2 and Fig. 12, the surface 130a of the third dummy separator 130, which is oriented in the direction indicated by the arrow A1, has the same structure as the surface 108a of the second dummy separator 108, which is oriented in the direction indicated by the arrow A1.

[0117] As in Fig. 2, a coolant flow field 52 is provided between the surface 130b of the third dummy separator 130, which is oriented in the direction indicated by arrow A2, and the first dummy separator 105 of the first final power generation unit 16. As shown in Fig. 2 and Fig. As shown in FIG. 12, the second gap 126, which corresponds to the flow field 66 for a fuel gas, is provided between the surface 130a of the third dummy separator 130 oriented in the direction indicated by arrow A1 and the third electrically conductive porous body 116 of the resin-framed dummy assembly 106 (oriented in the direction indicated by arrow A2). Further, in the first dummy cell 18, the second gap 126 is formed between the surface 108a of the second dummy separator 108 on the side indicated by arrow A1 and the resin-framed dummy assembly 106 on the side closer to the third electrically conductive porous body 116.

[0118] Further, in the first dummy cell 18, the first gap 109 is formed between the surface 105b of the first dummy separator 105 on the side indicated by the arrow A2 and the first electrically conductive porous body 112 on the side closer to the resin-framed dummy assembly 106, and between the surface 108b of the second dummy separator 108 on the side indicated by the arrow A2 and the first electrically conductive porous body 112 on the side closer to the resin-framed dummy assembly 106.

[0119] The second dummy cell 20 includes, from arrow A1 to arrow A2, a first dummy separator 105, a resin-framed dummy assembly 106 stacked on the first dummy separator 105, and a third dummy separator 130 stacked on the resin-framed dummy assembly 106. Therefore, in the second dummy cell 20, the first gap 109 is formed between the surface 105b of the first dummy separator 105 on the side indicated by arrow A2 and the resin-framed dummy assembly 106 on the side closer to the first electrically conductive porous body 112 (indicated by arrow A1).Furthermore, the second gap 126 is formed between the surface 130a of the third dummy separator 130 on the side indicated by arrow A1 and the resin-framed dummy assembly 106 on the side closer to the third electrically conductive porous body 116 (indicated by arrow A2). The third dummy cell 24 has the same structure as the second dummy cell 20.

[0120] Separators that can be used as the second dummy cell 20 and the third dummy cell 24 are not limited to having the above-described structure. For example, the second dummy cell 20 may have a structure in which, from arrow A1 to arrow A2, the second dummy separator 108 is provided, the resin-framed dummy assembly 106 is stacked on the second dummy separator 108, and the first separator 32 is stacked on the resin-framed dummy assembly 106. The third dummy cell 24 may have a structure in which, from the arrow A1 to the arrow A2, the first separator 32 is provided, the resin frame-equipped dummy assembly 106 is stacked on the first separator 32, and the second dummy separator 108 is stacked on the resin frame-equipped dummy assembly 106.

[0121] In the second final power generation unit 22, from the arrow A1 to the arrow A2, the first separator 32 is provided, the resin-framed MEA 34 is stacked on the first separator 32, the second dummy separator 108 is stacked on the resin-framed MEA 34, the resin-framed dummy assembly 106 is stacked on the second dummy separator 108, and the third dummy separator 130 is stacked on the resin-framed dummy assembly 106. Therefore, in the second final power generation unit 22, the first gap 109 is formed between the surface 108b of the second dummy separator 108 on the side indicated by the arrow A2 and the resin frame-equipped dummy assembly 106 on the side closer to the first electrically conductive porous body 112.

[0122] Furthermore, the second gap 126 is formed between the surface 130a of the third dummy separator 130 on the side indicated by the arrow A1 and the resin frame-equipped dummy assembly 106 on the side closer to the third electrically conductive porous body 116.

[0123] The connecting plates 26a, 26b are made of an electrically conductive material. The connecting plates 26a, 26b are made of a metal such as copper, aluminum, or stainless steel, for example. As shown in Fig. As shown in Figure 1, terminals 132a, 132b are provided at substantially central positions of the terminal plates 26a, 26b. The terminals 132a, 132b protrude outward in the stacking direction.

[0124] The terminal 132a is inserted into an insulating cylinder 134a to pass through a hole 136a of the insulator 28a and a hole 138a of the end plate 30a. The terminal 132a protrudes toward the outside of the end plate 30a. The terminal 132b is inserted into an insulating cylinder 134b to pass through a hole 136b of the insulator 28b and a hole 138b of the end plate 30b. The terminal 132b protrudes toward the outside of the end plate 30b.

[0125] The insulators 28a, 28b are made of an electrically insulating resin / plastic such as polycarbonate resin / plastic (PC), phenolic resin / plastic, etc. Recesses 140a, 140b are formed at the centers of the insulators 28a, 28b. The recesses 140a, 140b are open toward the stack body 14. The recesses 140a, 140b are connected to holes 136a, 136b.

[0126] Reaction gas channels are formed in the insulator 28a and the end plate 30a. A coolant supply channel 48 and a coolant discharge channel 50 are formed in the insulator 28b and the end plate 30b.

[0127] The terminal plate 26a and a thermal insulation body 142 are received in the recess 140a. A terminal plate 26b and an insulation body 142 are received in the recess 140b. The thermal insulation body 142 is formed by sandwiching an electrically conductive thermal insulation member 146 between a pair of electrically conductive thermal insulation plates 144. For example, the thermal insulation plate 144 is a flat porous carbon plate, and the thermal insulation member 146 is a metal plate having a wave-like / rib-like shape in cross section.

[0128] The thermal insulation plate 144 may be made of the same material as the thermal insulation element 146. Furthermore, the thermal insulation body 142 may include a thermal insulation plate 144 and a thermal insulation element 146. Furthermore, resin / plastic spacers may be inserted between the terminal plates 26a, 26b and the bottoms of the recesses 140a, 140b of the insulators 28a, 28b.

[0129] The fuel cell stack 10 essentially has the structure described above. A method for manufacturing a dummy cell according to an embodiment of the present invention will be described below, taking as an example a case in which the first dummy cell 18 of the fuel cell stack 10 is obtained.

[0130] First, a water-repellent treatment step of applying a water-repellent treatment to the second electrically conductive porous body 114 or the third electrically conductive porous body 116 is performed. The water-repellent treatment is performed, for example, by impregnating the second electrically conductive porous body 114 or the third electrically conductive porous body 116 with a dispersion liquid of FEP and then drying the second electrically conductive porous body 114 or the third electrically conductive porous body 116 for 30 minutes at 120°C.

[0131] Next, as in Fig. 11, a first stacking step is performed in which the first electrically conductive porous body 112, the second electrically conductive porous body 114, and the third electrically conductive porous body 116 are stacked, while the adhesive layer 118a or the adhesive layer 118b is provided between these layers in a dot pattern. In this way, the dummy assembly 110 can be obtained.

[0132] Next, as in Fig. 9 and Fig. 10, a resin / plastic frame bonding step is performed by providing the dummy resin / plastic frame member 111 around the dummy assembly 110 to obtain the resin / plastic frame-equipped dummy assembly 106.

[0133] Specifically, the outer exposed portion 116a of the third electrically conductive porous body 116 is stacked on the ledge 82e of the dummy resin / plastic frame member 111 on the side indicated by arrow A1, and the outer exposed portion 114b of the second electrically conductive porous body 114 is provided adjacent to the groove 82ha of the dummy resin / plastic frame member 111. The outer end surface 112a of the first electrically conductive porous body 112 is provided so as to face the inner end surface 82i of the dummy resin / plastic frame member 111. At this time, the outer exposed portion 114b of the second electrically conductive porous body 114 on the side indicated by the arrow A1 is brought into contact with the projecting end surface 82hb of the protrusion 82h.

[0134] Then, the resin / plastic protrusion 120a provided in the dummy resin / plastic frame member 111 is heated with a heater (not shown) and melted and solidified by applying a load to the resin / plastic protrusion 120a to discontinuously form the second connecting part 120, which is made of the second resin / plastic impregnation portion 120b and the second melted and solidified portion 120c as described above. In this way, by bonding the shoulder 82e of the dummy resin / plastic frame member 111 and the outer edge portion of the third electrically conductive porous body 116 together, it is possible to obtain the resin / plastic frame-equipped dummy assembly 106.

[0135] After two dummy assemblies 106 equipped with a resin / plastic frame have been obtained in the manner described above, as shown in Fig. 2, a second stacking step is performed by providing the first dummy separator 105, stacking the resin-framed dummy assembly 106 onto the first dummy separator 105, stacking the second dummy separator 108 onto the resin-framed dummy assembly 106, stacking the resin-framed dummy assembly 106 onto the second dummy separator 108, and stacking the third dummy separator 130 onto the resin-framed dummy assembly 106. In this way, it is possible to obtain the first dummy cell 18.

[0136] Note that the second dummy cell 20 and the third dummy cell 24 can be obtained by sandwiching the resin frame-equipped dummy assembly 106 between the first dummy separator 105 and the third dummy separator 130.

[0137] The operation of the fuel cell stack 10 comprising the first dummy cell 18, the second dummy cell 20, and the third dummy cell 24 obtained as described above will be described below. First, as shown in Fig. 1, an oxygen-containing gas is supplied to the oxygen-containing gas supply channel 40 of the end plate 30a. A fuel gas, for example, a hydrogen-containing gas, is supplied to the fuel gas supply channel 44 of the end plate 30a. A coolant, for example, pure water, ethylene glycol, or oil, is supplied to the coolant supply channels 48 of the end plate 30b.

[0138] As in Fig. 4 and Fig. 5, the oxygen-containing gas supplied to the oxygen-containing gas supply channel 40 flows into the oxygen-containing gas flow field 56 and the first gap 109 through the communication channel 125 formed within the inlet communication grooves 62a. Thus, the oxygen-containing gas flows in the longitudinal direction along each of the separators and the dummy separators (the first dummy separator 105, the second dummy separator 108, the third dummy separator 130) from the side indicated by the arrow B1 to the side indicated by the arrow B2, and the oxygen-containing gas is supplied to the cathode 86 of the membrane electrode assembly 80 and the dummy assembly 110.

[0139] As in Fig. 3, the fuel gas supplied to the fuel gas supply channel 44 flows through the fuel gas supply holes 72a into the fuel gas flow field 66 of the second separator 36 and the third separator 38. Therefore, the fuel gas flows in the longitudinal direction along each of the separators from the side indicated by the arrow B2 to the side indicated by the arrow B1, and the fuel gas is supplied to the anode 88 of the membrane electrode assembly 80. Meanwhile, as shown in Fig. 12, the flow of the fuel gas into the second gap 126 of the second dummy separator 108 and the third dummy separator 130 is blocked by the inlet blocking part 122a.

[0140] In the membrane electrode assembly 80, to which the reaction gases are supplied as described above, the oxygen-containing gas supplied to each cathode 86 and the fuel gas supplied to each anode 88 are consumed in electrochemical reactions in the first electrode catalyst layer 90 and the second electrode catalyst layer 94 to generate electricity.

[0141] Then, after the oxygen-containing gas has been supplied to each cathode 86 and a portion of the oxygen-containing gas has been consumed at the cathode 86, the oxygen-containing gas is discharged from each of the oxygen-containing gas flow field 56 and the first space 109 through the communication channel 125 formed within the outlet communication grooves 62b to the oxygen-containing gas discharge channel 46. Then, the oxygen-containing gas is discharged through the oxygen-containing gas discharge channel 46 of the end plate 30a to the exterior of the fuel cell stack 10.

[0142] Similarly, after the fuel gas is supplied to each anode 88, a portion of the fuel gas is supplied from the fuel gas flow field 66 through the interior of the fuel gas discharge holes 72b to the fuel gas discharge channel 42. Then, the fuel gas is discharged through the fuel gas discharge channel 42 of the end plate 30a to the exterior of the fuel cell stack 10.

[0143] In this context, the flow of fuel gas between the second space 126 and the fuel gas discharge channel 42 is blocked by the outlet blocking part 122b. Therefore, as described above, the flow of fuel gas into the second space 126 is blocked by the inlet blocking part 122a, and the entry of fuel gas from the fuel gas discharge channel 42 into the second space 126 is prevented by the outlet blocking part 122b. As a result, the flow of fuel gas in the second space 126 is blocked by the blocking part. Thus, the second space 126 functions as a heat insulating space.

[0144] Furthermore, the coolant supplied to each of the coolant supply channels 48 flows into the coolant flow field 52 between the third dummy separator 130 and the first separator 32, which are adjacent to each other, and the coolant flow field 52 between the third separator 38 and the first separator 32, which are adjacent to each other. The coolant that has flowed from each of the coolant supply channels 48 on the side indicated by arrow C1 and the coolant that has flowed from the coolant supply channel 48 on the side indicated by arrow C2 flow toward each other in the direction indicated by arrows C1 and C2, then flow in the direction indicated by arrow B2, and move away from each other in the direction indicated by arrows C1 and C2, while the membrane electrode assembly 80 is cooled.The coolant is discharged through each of the coolant discharge channels 50.

[0145] As described above, in each of the dummy cells of the fuel cell stack 10 according to the embodiment of the present invention, the dummy assembly 110 is formed by stacking the first electrically conductive porous body 112, the second electrically conductive porous body 114, and the third electrically conductive porous body 116 together. Unlike the dummy cell (not shown) according to the comparative example, which uses the metal plate instead of the electrolyte membrane 84 of the membrane electrode assembly 80, this dummy assembly 110 can be obtained at low cost because there is no need to provide elements such as the electrically conductive porous body and the metal plate, which comprise a plurality of materials.Furthermore, since the dummy assembly 110 is made of the three electrically conductive porous bodies, namely the first electrically conductive porous body 112, the second electrically conductive porous body 114, and the third electrically conductive porous body 116, and the first gas diffusion layer 92 and the second gas diffusion layer 96 of the membrane electrode assembly 80 are also made of the electrically conductive porous bodies, it is possible to reduce the cost of providing components associated with each of the dummy cells.

[0146] Furthermore, the dummy assembly 110 is formed by stacking the three electrically conductive porous bodies having different surface sizes, namely the first electrically conductive porous body 112, the second electrically conductive porous body 114, and the third electrically conductive porous body 116, to provide steps for bonding the dummy resin frame member 104 in the outer peripheral portion of the dummy assembly 110. Therefore, for example, without requiring a special production process for providing a step in an outer peripheral portion of the electrically conductive porous body (not shown) that is integrally formed, it is possible to obtain the dummy assembly 110 relatively easily.

[0147] By providing the above dummy assembly 110, it is possible to provide each of the dummy cells having a simple and inexpensive structure.

[0148] Furthermore, each of the dummy cells includes the dummy assembly 110 in correspondence with the membrane electrode assembly 80 of the power generation cell 12. That is, since each of the dummy cells does not include the electrolyte membrane 84, the first electrode catalyst layer 90, and the second electrode catalyst layer 94, power generation is not performed and no water is produced as a result of power generation. Therefore, each of the dummy cells itself acts as a thermal insulation layer, and it is possible to prevent water condensation in each of the dummy cells.

[0149] Since the first dummy cell 18 and the second dummy cell 20 are provided at the end of the stacked body 14 in the direction indicated by arrow A1, and the third dummy cell 24 is provided at the end of the stacked body 14 oriented in the direction indicated by arrow A2, it is possible to improve thermal insulation performance at the end of the stacked body 14. Therefore, even in a low-temperature environment, it is possible to suppress a temperature drop at the end of the stacked body 14 compared to the central position of the stacked body 14.

[0150] Furthermore, since it is possible to improve the thermal insulation performance at the end of the stack body 14 as described above, even when the fuel cell stack 10 is put into operation in a subfreezing temperature environment, it is possible to effectively raise the temperature of the entire stack body 14. Therefore, it is possible to suppress voltage drop due to freezing of the produced water, etc., at the ends of the stack body 14.

[0151] Accordingly, in the fuel cell stack 10, it is possible to suppress the influence of the outside air temperature on the fuel cell stack 10 and improve the stability of power generation by the dummy cells each having a simple and inexpensive structure.

[0152] Since the water-repellent treatment is applied to the second electrically conductive porous body 114 or the third electrically conductive porous body 116 in the fuel cell stack 10, it is possible to prevent the stagnation of liquid water, such as condensate and / or produced water, in each of the dummy cells. Therefore, it is possible to prevent freezing of each of the dummy cells even in low-temperature environments.

[0153] As described above, the dummy assembly 110 of each dummy cell that does not perform power generation eliminates the need to apply a dimensional tolerance as is the case with the membrane electrode assembly 80 of the power generation cell 12 that performs power generation. Furthermore, the dummy resin / plastic frame member 111 provided at the outer end of the dummy assembly 110 has the same structure as the resin / plastic frame member 82 provided at the outer end of the membrane electrode assembly 80.

[0154] By making the surface area of ​​the third electrically conductive porous body 116 larger than the surface area of ​​the second gas diffusion layer 96, it is possible to make the connection area between the dummy assembly 110 and the dummy resin / plastic frame member 111 larger than the connection area between the membrane electrode assembly 80 and the resin / plastic frame member 82. In this way, it is possible to improve the connection strength of the dummy resin / plastic frame member 111 and the dummy assembly 110.

[0155] At the time of aligning the dummy resin frame member 111 with the dummy assembly 110 before these components are bonded together, for manufacturing the resin frame-equipped dummy assembly 106, it is possible to perform positional adjustment in accordance with the distance L2 between the first stepped surface 82d of the dummy resin frame member 111 and the outer end surface 116b of the third electrically conductive porous body 116. Therefore, by increasing the surface area of ​​the third electrically conductive porous body 116 and reducing the distance L2, it is possible to improve the positional accuracy between the dummy resin frame member 111 and the dummy assembly 110.

[0156] Thus, in the fuel cell stack 10, it is possible to connect the resin frame member 82 and the dummy assembly 110 together without causing rattling in each of the dummy cells. That is, it is possible to reduce the manufacturing cost of the fuel cell stack 10 and improve the power generation stability of the fuel cell stack 10.

[0157] Furthermore, in the fuel cell stack 10, the inlet blocking part 122a and the outlet blocking part 122b are provided between the portion of the resin-frame-equipped dummy assembly 106 located closer to the third electrically conductive porous body 116 in the stacking direction and each of the second dummy separator 108 and the third dummy separator 130. In this way, as described above, since the second space 126 functions as a heat insulating space, it is possible to improve the heat insulating performance in each of the dummy cells. Furthermore, since the flow of fuel gas to the second space 126 is blocked, it is possible to reduce the amount of fuel gas discharged from the fuel cell stack 10 without contributing to electrochemical reactions for power generation.

[0158] Specifically, the oxygen-containing gas is supplied to the oxygen-containing gas supply channel 40 in the direction indicated by arrow A1 in the humidified state. If the water vapor in the oxygen-containing gas is condensed to produce condensed water in the liquid state, and the condensed water is injected into the power generation cells 12, the diffusion efficiency of the reaction gases may be undesirably reduced.

[0159] To address this problem, in the fuel cell stack 10 described above, the connecting channel 125 is provided between the first electrically conductive porous body 112 of the resin-framed dummy assembly 106 in the stacking direction and each of the first dummy separator 105 and the second dummy separator 108. In the structure, the supplied oxygen-containing gas supplied to the oxygen-containing gas supply channel 40 of each dummy cell flows through the first gap 109 via the connecting channel 125. Therefore, even if the oxygen-containing gas contains condensed water, the condensed water is collected by each of the dummy cells, and it is possible to prevent the condensed water from being splashed into the power generation cells 12.

[0160] During the high-load power generation of the fuel cell stack 10, or when the power generation of the fuel cell stack 10 is stopped and the flow rate of the oxygen-containing gas flowing through the first gap 109 is increased by the drying process, or when each of the dummy cells is dried, the condensate, etc., collected by each of the dummy cells is smoothly discharged in a liquid state from each of the dummy cells.

[0161] In the dummy assembly 110, the water-repellent treatment is applied to the third electrically conductive porous body 116 facing the second gap 126 or the second electrically conductive porous body 114 adjacent to the third electrically conductive porous body 116. Therefore, in each of the dummy cells, it is possible to prevent liquid water from flowing from the first gap 109 into the second gap 126, where the flow of fuel gas is blocked as described above.

[0162] This makes it possible to more effectively facilitate water drainage from each of the dummy cells through the oxygen-containing gas flowing through the first gap 109. Accordingly, it is possible to suppress the stagnation of liquid water within the dummy cell. Therefore, even in a low-temperature environment, it is possible to prevent each of the dummy cells from freezing. As described above, in the fuel cell stack 10, it is possible to improve the stability of power generation by each of the dummy cells where freezing is prevented.

[0163] In the fuel cell stack 10, the dummy resin frame member 10 and the resin frame member 82 have the same structure. Therefore, the same structure can be applied to the dummy resin frame member 104 and the resin frame member 82 of the power generation cell 12. Accordingly, each of the dummy cells can have a simpler and more cost-effective structure.

[0164] In the fuel cell stack 10, the three electrically conductive porous bodies, that is, the first electrically conductive porous body 112, the second electrically conductive porous body 114, and the third electrically conductive porous body 116, are made of the same material. Therefore, unlike the dummy cell according to the comparative example in which the metal plate is held by the electrically conductive porous body, in each of the dummy cells of the fuel cell stack 10 according to the embodiment of the present invention, it is possible to reduce the contact resistance in the dummy assembly 110. Since it is possible to reduce the internal resistance of the fuel cell stack 10 in the structure, it is possible to improve the power generation efficiency.It should be noted that the three electrically conductive porous bodies (the first electrically conductive porous bodies 112, the second electrically conductive porous bodies 114, and the third electrically conductive porous bodies 116 may be made of different materials).

[0165] Unlike the power generation cell 12, in which the outer portions of the resin / plastic frame member 82 and the membrane electrode assembly 80 are firmly connected to each other to suppress cross leaks, etc., there is no need for cross leak suppression in each of the dummy cells that do not perform power generation. Therefore, by forming the second connecting part 120 at which the dummy assembly 110 and the dummy resin / plastic frame member 104 are discontinuously connected to each other in the circumferential direction of the outer periphery of the dummy assembly 110 (third electrically conductive porous body 116), it becomes possible to simplify the step of connecting the dummy assembly 110 and the dummy resin / plastic frame member 111 and to obtain each of the dummy cells more efficiently. Furthermore, it is possible to improve the production efficiency of the fuel cell stack 10.It should be noted that the second connecting part 120 may be formed around the dummy assembly 110.

[0166] In the embodiment of the present invention, in the second connection part 120, the resin protrusion 120a as the part of the resin frame member 82 includes the second resin impregnation portion 120b impregnated with the third electrically conductive porous body 116. Therefore, unlike, for example, the dummy resin frame member 111 and the dummy assembly 110 that are bonded using adhesive only between the dummy resin frame member 111 and the dummy assembly 110, it is possible to improve the bonding strength of the dummy resin frame member 111 and the dummy assembly 110.

[0167] As described above, the second resin / plastic impregnation portion 120b is provided discontinuously in the circumferential direction in the outer exposed portion 116a of the third electrically conductive porous body 116. Therefore, unlike the case where the second resin / plastic impregnation portion 120b is provided around the outer exposed portion 116a of the third electrically conductive porous body 116, it is possible to reduce the portion heated at the time of deforming (melting) the dummy resin / plastic frame member 111. As a result, it is possible to suppress the occurrence of warpage, etc., of the dummy resin / plastic frame member 111 due to heating.

[0168] In the embodiment of the present invention, the second connecting part 120 (second resin / plastic impregnation portion 120b) is provided in the outer peripheral portion of the third electrically conductive porous body 116, and the second connecting part 120 (second resin / plastic impregnation portion 120b) is not provided in the first electrically conductive porous body 112 or the second electrically conductive porous body 114. Also in this case, it is possible to simplify the joining step of joining the dummy resin / plastic frame member 111 and the dummy assembly 110 and to suppress warpage of the dummy resin / plastic frame member 111 due to heating.

[0169] In the above embodiment, the resin protrusion 120a, as part of the dummy resin frame member 111, is deformed by heating. In this way, with a simple structure, it is possible to easily and appropriately form the second connecting part 120. Thus, it becomes possible to obtain each of the dummy cells more efficiently. Furthermore, it is possible to improve the production efficiency of the fuel cell stack 10.

[0170] The present invention is not limited to the embodiments described above. Various modifications may be made without departing from the spirit of the present invention.

[0171] For example, as in Fig. 13 and Fig. 14, in the direction indicated by arrow B2 at one end of the dummy assembly 110, at the lower position in the vertical direction (indicated by arrow C2) of the dummy assembly 110, a through hole 117 may be provided, which passes through the first electrically conductive porous body 112, the second electrically conductive porous body 114 and the third electrically conductive porous body 116. In the examples from the Fig. 13 and Fig. 14, the cross section orthogonal to the axial direction of the through-hole 117 has a circular shape. However, the present invention is not limited in this respect. Furthermore, the through-holes 117 formed in the first electrically conductive porous body 112, the second electrically conductive porous body 114, and the third electrically conductive porous body 116 may have the same size or different sizes from each other.

[0172] The first gap 109 of the dummy assembly 110, which is provided adjacent to the first electrically conductive porous body 112, and the second gap 126 of the dummy assembly 110, which is provided adjacent to the third electrically conductive porous body 116, are connected to each other at a position adjacent to the oxygen-containing gas discharge channel 46 through the through-hole 117. That is, in each of the dummy cells, the first gap 109 and the second gap 126 on both sides of the dummy assembly 110 are connected to each other at the position adjacent to the oxygen-containing gas discharge channel 46 through the through-hole 117.

[0173] As described above, the through-hole 117 is provided in the dummy assembly 110 to connect the first gap 109 and the second gap 126 in the vertical direction at the lower position. Therefore, even if the liquid water enters the second gap 126, the liquid water moves toward the through-hole 117 by gravity, and the liquid water is guided toward the first gap 109 through the through-hole 117.

[0174] By allowing the oxygen-containing gas to flow through the first gap 109, it becomes possible to appropriately facilitate water drainage from each of the dummy cells and prevent stagnation of liquid water within each of the dummy cells. Therefore, even in a low-temperature environment, it is possible to prevent freezing of each of the dummy cells. As a result, by preventing freezing of each of the dummy cells, it is possible to improve the power generation stability of the fuel cell stack 10.

[0175] As described above, in the fuel cell stack 10, the through-hole 117 of the dummy assembly 110 is provided adjacent to the oxygen-containing gas discharge channel 46. This structure allows the liquid water supplied from the second gap 126 to the first gap 109 through the through-hole 117 to be discharged to the exterior of each of the dummy cells (oxygen-containing gas discharge channel 46).

[0176] As described above, in the fuel cell stack 10, each of the separators and each of the dummy separators has a rectangular shape with the longitudinal direction oriented in the horizontal direction. Further, the oxygen-containing gas supply channel 40 is provided in each of the separators and each of the dummy separators at the upper end in the vertical direction (indicated by arrow C1), and the oxygen-containing gas discharge channel 46 is provided in each of the separators and the dummy separators at the lower position in the vertical direction (indicated by arrow C2). With this structure, it is possible to properly discharge water by effectively guiding the liquid water in each of the power generation cells 12 and each of the dummy cells to the oxygen-containing gas discharge channel 46 by gravity.

[0177] As described above, in the fuel cell stack 10, the oxygen-containing gas flows through the first gap 109 in a direction aligned with the longitudinal direction of each of the dummy separators. This structure allows the liquid water in each of the dummy cells to be easily directed through the first gap 109 toward the oxygen-containing gas discharge channel 46 to discharge the water.

[0178] In the illustrated embodiment, a circular through-hole 117 is formed in the dummy assembly 110 in a plan view adjacent to the oxygen-containing gas discharge channel 46. However, the present invention is not limited in this respect. The through-hole 117 can be provided at any position below the dummy assembly 110 in the vertical direction. Furthermore, the through-hole 117 should have a shape that can connect the first gap 109 and the second gap 126. Furthermore, a plurality of through-holes 117 can be provided in the dummy assembly 110.

[0179] In the above embodiments, a water-repellent treatment is applied to the third electrically conductive porous body 116 or the second electrically conductive porous body 114. To effectively prevent the ingress of liquid water into the second gap 126, the water-repellent treatment should particularly preferably be applied to the third electrically conductive porous body 116 located near the second gap 126. Furthermore, even if a water-repellent treatment is applied to the second electrically conductive porous body 114 adjacent to the third electrically conductive porous body 116, it is also possible to effectively prevent the ingress of liquid water into the second gap 126. However, the present invention is not limited in this respect.A water-repellent treatment may be applied to the first electrically conductive porous body 112.

[0180] In the fuel cell stack 10 according to the above embodiment, the first final power generation unit 16, the first dummy cell 18, and the second dummy cell 20 are stacked together on the side of the stack body 14 indicated by the arrow A1, and the second final power generation unit 22 and the third dummy cell 24 are stacked on the side of the stack body 14 in the direction indicated by the arrow A2.

[0181] As described above, the number of dummy cells provided on the side of the stacked body 14 indicated by arrow A1, i.e., on the oxygen-containing gas inlet side, is large compared to the number of dummy cells provided on the side of the stacked body 14 indicated by arrow A2, i.e., on the oxygen-containing gas outlet side. In this way, it becomes possible to effectively suppress the ingress of condensed water into the power generation cells 12. However, the number of dummy cells is not particularly limited as long as the fuel cell stack 10 includes the dummy cell on at least one end side of the stacked body 14 in the stacking direction.

[0182] Furthermore, the first final power generation unit 16 or the second final power generation unit 22 is interposed between the power generation cell 12 and the first dummy cell 18 or the third dummy cell 24. In this way, it is possible to cool the membrane electrode assemblies 80 in the first final power generation unit 16 and the second final power generation unit 22, which perform power generation at both ends of the stacked body 14 in the stacking direction, under the same conditions as the other membrane electrode assembly 80. As a result, it is possible to achieve the same balance between heat generation and cooling throughout the entire stacked body 14. Accordingly, it is possible to achieve further improvement in power generation performance and power generation stability.

[0183] However, the first final power generation unit 16 and the second final power generation unit 22 are not essential. The fuel cell stack 10 may include only one of the first final power generation unit 16 and the second final power generation unit 22, or the fuel cell stack 10 may not include either of the first final power generation unit 16 and the second final power generation unit 22.

[0184] A fuel cell stack (10) comprises at least one stacked body (14) formed by stacking a plurality of power generation cells (12) in a stacking direction, and a first dummy cell (18) provided at one end of the stacked body (14) in the stacking direction. The power generation cell (12) comprises a membrane electrode assembly (80). The first dummy cell (18) comprises a dummy assembly (110) formed by stacking three electrically conductive porous bodies (112, 114, 116), each having a different area, together, a dummy resin / plastic frame member (111) formed around the dummy assembly (110), and dummy separators (105, 108, 130).

Claims

[1] Fuel cell stack (10), comprising: a stacked body (14) comprising a plurality of power generation cells (12) stacked together in a stacking direction, the power generation cells (12) each comprising a membrane electrode assembly (80), a resin / plastic frame member (82) provided around the membrane electrode assembly (80), and separators (32, 36, 38) between which the membrane electrode assembly (80) is sandwiched, the membrane electrode assembly (80) comprising an electrolyte membrane (84) and electrodes (86, 88) provided on both sides of the electrolyte membrane (84), the electrodes (86, 88) each having a gas diffusion layer (92, 96) made of an electrically conductive porous body; a dummy cell (18, 20, 24) provided at least one end of the stacked body (14) in the stacking direction; wherein the dummy cell (18, 20, 24) comprises a dummy assembly (110) corresponding to the membrane electrode assembly (80), a dummy resin / plastic frame member (111) provided around the dummy assembly (110), and dummy separators (105, 108, 130) between which the dummy assembly (110) is sandwiched; characterized by , that the dummy arrangement (110) is formed by stacking three electrically conductive porous bodies (112, 114, 116) together, each having a different surface area, the three electrically conductive porous bodies (112, 114, 116) are stacked to form a stepped surface at an outer edge portion of the dummy assembly (110), and the dummy resin / plastic frame member (111) is connected to the stepped surface. [2] Fuel cell stack (10) according to claim 1, wherein each of the separators (32, 36, 38) and the dummy separators (105, 108, 130) has a channel (40, 46) for an oxygen-containing gas, which is adapted to allow an oxygen-containing gas to flow in the stacking direction of the stacked body (14), and a channel (42, 44) for a fuel gas, which is adapted to allow a fuel gas to flow in the stacking direction of the stacked body (14); a separator of the separators (32, 36, 38) facing one of the electrodes (86, 88) of the membrane electrode assembly (80) has a flow field (56) for an oxygen-containing gas along which the oxygen-containing gas flows; a further separator of the separators (32, 36, 38), which faces another of the electrodes (86, 88) of the membrane electrode assembly (80), has a flow field (66) for a fuel gas along which the fuel gas flows; a first gap (109), which corresponds to the flow field (56) for an oxygen-containing gas, is formed between a dummy separator of the dummy separators (105, 108, 130), which faces one end side of the dummy arrangement (110) in the stacking direction, and the one end side of the dummy arrangement (110), a second gap (126), which corresponds to the flow field (66) for a fuel gas, is formed between a further dummy separator of the dummy separators (105, 108, 130), which faces a further end side of the dummy arrangement (110) in the stacking direction, and the further end side of the dummy arrangement (110), a connecting channel (125) adapted to allow a flow of the oxygen-containing gas is provided between the channel (40, 46) for an oxygen-containing gas and the first space (109); and a blocking part (122a, 122b) adapted to block a flow of the fuel gas is provided between the channel (42, 44) for a fuel gas and the second space (126). [3] The fuel cell stack (10) according to claim 1, wherein the dummy resin / plastic frame member (111) has a same structure as the resin / plastic frame member (82). [4] Fuel cell stack (10) according to claim 1, wherein the three electrically conductive porous bodies (112, 114, 116) are made of a same material. [5] The fuel cell stack (10) according to claim 1, wherein a connecting part (120) configured to connect the dummy assembly (110) and the dummy resin / plastic frame member (111) to each other is formed discontinuously in a circumferential direction of the dummy assembly (110). [6] The fuel cell stack (10) according to claim 1, wherein the dummy assembly (110) is formed by stacking the three electrically conductive porous bodies (112, 114, 116) comprising a first electrically conductive porous body (112), a second electrically conductive porous body (114) having an area larger than that of the first electrically conductive porous body (112), and a third electrically conductive porous body (116) having an area larger than that of the second electrically conductive porous body (114); and the area of ​​the third electrically conductive porous body (116) is larger than an area of ​​the gas diffusion layer (92, 96). [7] The fuel cell stack (10) according to claim 6, wherein the second electrically conductive porous body (114) is provided at a center of the dummy assembly (110) in the stacking direction; the dummy resin / plastic frame member (111) comprises: a contact surface (82hb) adapted to contact an outer exposed portion (114b) of the second electrically conductive porous body (114) extending outward beyond an outer end surface (112a) of the first electrically conductive porous body (112); and a connecting surface (82ea) connected by a connecting part (120) to an outer exposed portion (116a) of the third electrically conductive porous body (116) which extends outward beyond an outer end surface (114a) of the second electrically conductive porous body (114), and wherein the connecting part (120) is formed discontinuously in a circumferential direction of the outer exposed portion (116a) of the third electrically conductive porous body (116). [8] The fuel cell stack (10) according to claim 7, wherein the connecting part (120) comprises an impregnation portion (120b) wherein the outer exposed portion (116a) of the third electrically conductive porous body (116) is impregnated with a part of the molten dummy resin / plastic frame member (111). [9] The fuel cell stack (10) according to claim 8, wherein a part of the dummy resin / plastic frame member (111) is a resin / plastic projection (120a) provided on an outer side beyond the joining surface (82ea) of the dummy resin / plastic frame member (111) in such a manner that the resin / plastic projection (120a) projects in a thickness direction of the resin / plastic frame member (82). [10] The fuel cell stack (10) according to claim 1, wherein a water-repellent treatment is applied to one of the three electrically conductive porous bodies (112, 114, 116). [11] The fuel cell stack (10) according to claim 10, wherein the dummy assembly (110) is formed by stacking the three electrically conductive porous bodies (112, 114, 116) comprising a first electrically conductive porous body (112), a second electrically conductive porous body (114) stacked on the first electrically conductive porous body (112), and a third electrically conductive porous body (116) stacked on the second electrically conductive porous body (114); a water-repellent treatment is applied to one of the second electrically conductive porous body (114) and the third electrically conductive porous body (116), each of the separators (32, 36; 38) and the dummy separators (105, 108, 130) has a channel (40, 46) for an oxygen-containing gas which is adapted to allow an oxygen-containing gas to flow in the stacking direction of the stacked body (14), and a channel (42, 44) for a fuel gas which is adapted to allow a fuel gas to flow in the stacking direction of the stacked body (14); the separator (32, 36, 38) facing one of the electrodes (86, 88) of the membrane electrode assembly (80) has a flow field (56) for an oxygen-containing gas along which the oxygen-containing gas flows; the separator (32, 36, 38) facing another of the electrodes (86, 88) of the membrane electrode assembly (80) has a flow field (66) for a fuel gas along which the fuel gas flows; a first gap (109) corresponding to the flow field (56) for an oxygen-containing gas is formed between the dummy separator (105, 108, 130) and the first electrically conductive porous body (112); a second gap (126) corresponding to the flow field (66) for a fuel gas is formed between the dummy separator (105, 108, 130) and the third electrically conductive porous body (116); a connecting channel (125) adapted to allow a flow of the oxygen-containing gas is provided between the channel (40, 46) for an oxygen-containing gas and the first space (109); and a blocking part (122a, 122b) adapted to block a flow of the fuel gas is provided between the channel (42, 44) for a fuel gas and the second space (126). [12] The fuel cell stack (10) according to claim 11, wherein a connecting part (120) configured to connect the dummy assembly (110) and the dummy resin / plastic frame member (111) to each other is discontinuously formed in a circumferential direction of the electrically conductive porous body (116) having a largest area among the three electrically conductive porous bodies (112, 114, 116). [13] The fuel cell stack (10) according to claim 1, wherein each of the separators (32, 36, 38) and the dummy separators (105, 108, 130) has a channel (40, 46) for an oxygen-containing gas, which is configured to allow an oxygen-containing gas to flow in the stacking direction of the stack body (14), and a channel (42, 44) for a fuel gas, which is configured to allow a fuel gas to flow in the stacking direction of the stack body (14), a separator of the separators (32, 36, 38) facing one of the electrodes (86, 88) of the membrane electrode assembly (80) has a flow field (56) for an oxygen-containing gas along which the oxygen-containing gas flows; a further separator of the separators (32, 36, 38), which faces another of the electrodes (86, 88) of the membrane electrode assembly (80), has a flow field (66) for a fuel gas along which the fuel gas flows; a first gap (109) corresponding to the flow field (56) for an oxygen-containing gas is formed between a dummy separator of the dummy separators (105, 108, 130) facing one end side of the dummy assembly (110) in the stacking direction and one end side of the dummy assembly (110); a second gap (126) corresponding to the flow field (66) for a fuel gas is formed between another dummy separator of the dummy separators (105, 108, 130) facing another end side of the dummy assembly (110) in the stacking direction and the other end side of the dummy assembly (110); a connecting channel (125) adapted to allow a flow of the oxygen-containing gas is provided between the channel (40, 46) for an oxygen-containing gas and the first space (109); and the dummy assembly (110) has a through hole (117) connecting the first gap (109) and the second gap (126) in a vertical direction at a lower position. [14] The fuel cell stack (10) according to claim 13, wherein the through hole (117) of the dummy assembly (110) is provided on an outlet side of the oxygen-containing gas flowing through the first gap (109), adjacent to the oxygen-containing gas channel (46). [15] The fuel cell stack (10) according to claim 13 or 14, wherein the separators (32, 36, 38) and the dummy separators (105, 108, 130) have a rectangular shape, and a longitudinal direction of the rectangular shape is aligned in a horizontal direction; the channel (40) for an oxygen-containing gas on an inlet side, which is adapted to supply the oxygen-containing gas to the oxygen-containing gas flow field (56) and the first gap (109), is provided at an upper position in the vertical direction of the separators (32, 36, 38) and the dummy separators (105, 108, 130); and the channel (46) for an oxygen-containing gas on an outlet side, which is adapted to discharge the oxygen-containing gas from the flow field (56) and the first gap (109), is provided at a lower position in the vertical direction of the separators (32, 36, 38) and the dummy separators (105, 108, 130). [16] The fuel cell stack (10) according to any one of claims 13 to 15, wherein the first gap (109) is configured to allow the oxygen-containing gas to flow in a direction aligned with a longitudinal direction of the dummy separators (105, 108, 130). [17] The fuel cell stack (10) according to claim 1, wherein the three electrically conductive porous bodies (112, 114, 116) comprise a first electrically conductive porous body (112), a second electrically conductive porous body (114) having an area larger than that of the first electrically conductive porous body (112), and a third electrically conductive porous body (116) having an area larger than that of the second electrically conductive porous body (114); and the dummy resin / plastic frame member (111) comprises an outer edge portion (82b), a step (82e) which projects inward from an inner end of the outer edge portion (82b) over an entire circumference through a first stepped surface (82d), and a thin portion (82g) which projects inward from an inner end of the step (82e) over an entire circumference through a second stepped surface (82f); an outer edge portion of the third electrically conductive porous body (116) overlaps with the shoulder (82e) of the dummy resin / plastic frame member (111); and an outer edge portion of the second electrically conductive porous body (114) is adjacent to the thin portion (82g) of the dummy resin / plastic frame member (111); and an outer end face (112a) of the first electrically conductive porous body (112) faces an inner end face (82i) of the dummy resin / plastic frame member (111). [18] The fuel cell stack (10) according to claim 17, wherein a thickness of the second electrically conductive porous body (114) is greater than a height of the second stepped surface (82f). [19] The fuel cell stack (10) according to claim 17 or 18, wherein a gap is formed between the thin portion (82g) of the dummy resin / plastic frame member (111) and the third electrically conductive porous body (116). [20] Dummy cell (18, 20, 24) for a fuel cell stack (10), the fuel cell stack comprising: a stacked body (14) comprising a plurality of power generation cells (12) stacked together in a stacking direction, the power generation cells (12) each comprising a membrane electrode assembly (80), a resin / plastic frame member (82) provided around the membrane electrode assembly (80), and separators (32, 36, 38) between which the membrane electrode assembly (80) is sandwiched, the membrane electrode assembly (80) comprising an electrolyte membrane (84) and electrodes (86, 88) provided on both sides of the electrolyte membrane (84), the electrodes each having a gas diffusion layer (92, 96) made of an electrically conductive porous body; wherein the dummy cell (18, 20, 24) is provided at least at one end of the stacked body (14) in the stacking direction; wherein the dummy cell (18, 20, 24) comprises a dummy assembly (110) corresponding to the membrane electrode assembly (80), a dummy resin / plastic frame member (111) provided around the dummy assembly (110), and dummy separators (105, 108, 130) between which the dummy assembly (110) is sandwiched; characterized by , that the dummy arrangement (110) is formed by stacking three electrically conductive porous bodies (112, 114, 116), each having a different surface area, the three electrically conductive porous bodies (112, 114, 116) are stacked to form a stepped surface at an outer edge portion of the dummy assembly (110), and the dummy resin / plastic frame member (111) is connected to the stepped surface. [21] A method for producing a dummy cell (18, 20, 24) which is provided in a stacking direction at least at one end of a stack body (14) of a fuel cell stack (10); wherein the fuel cell stack (10) comprises: a stacked body (14) comprising a plurality of power generation cells (12) stacked together in the stacking direction, the power generation cells each comprising a membrane electrode assembly (80), a resin / plastic frame member (82) provided around the membrane electrode assembly (80), and separators (32, 36, 38) between which the membrane electrode assembly (80) is sandwiched, the membrane electrode assembly comprising an electrolyte membrane (84) and electrodes (86, 88) provided on both sides of the electrolyte membrane (84), the electrodes each having a gas diffusion layer (92, 96) made of an electrically conductive porous body; the method comprising: a water-repellent treatment step of applying a water-repellent treatment to one of three electrically conductive porous bodies (112, 114, 116) each having a different area size; a first stacking step of stacking the three electrically conductive porous bodies (112, 114, 116) together to form a dummy assembly (110) corresponding to the membrane electrode assembly (80); a resin / plastic frame bonding step of providing the dummy assembly (110) with a dummy resin / plastic frame member (111) extending around the dummy assembly (110), thereby obtaining a resin / plastic frame-equipped dummy assembly (110); and a second stacking step of sandwiching the dummy assembly (110) equipped with a resin / plastic frame between dummy separators (105, 108, 130) to obtain the dummy cell (18, 20, 24), characterized by , that in the first stacking step, the three electrically conductive porous bodies (112, 114, 116) are stacked to form a stepped surface at an outer edge portion of the dummy assembly (110), and in the resin / plastic frame bonding step, the dummy resin / plastic frame member (111) is bonded to the stepped surface.

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