JP2013114899A - Fuel cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell stack capable of improving stability of electric output by suppressing stay of water droplets in the vicinity of a connection part at the connection part of the inner wall surface of a manifold and a gas passage groove to suppress blocking of the gas passage groove by the water droplets, even in situation where the water droplets are produced in the manifold, or flows into the manifold.SOLUTION: A plurality of electrolyte membrane-electrode assembly each formed by holding a solid polymer electrolyte membrane between a pair of gas diffusion electrodes, and a plurality of separators each including a gas passage groove forming a gas passage by abutting on the gas diffusion electrodes are laminated to form this fuel cell stack. The stack includes the manifold connected to one end of the upstream side of the plurality of gas passage grooves, and hydrophilic improving treatment is applied to a portion adjacent to the connection part of the manifold and the gas passage groove in the inner wall surface of the manifold.

Description

  The present invention relates to a fuel cell stack.

  A polymer electrolyte fuel cell (hereinafter referred to as PEFC) has a MEA (Membrane-Electrode-Assembly: electrolyte membrane-electrode assembly), and both main surfaces of the MEA are respectively provided with a fuel gas containing hydrogen and air. It is an apparatus that generates electric power and heat by exposing it to an oxidant gas containing oxygen and causing the fuel gas and oxidant gas to react electrochemically.

  In order to supply fuel gas and oxidant gas to the MEA, the MEA is in contact with a separator in which a gas flow channel groove is formed.

  In addition, one end on the upstream side of the gas flow channel groove is connected to a manifold in order to ensure equal distribution of the amount of gas supplied to each cell.

  By the way, since the fuel cell stack and the fuel cell system are cooled when the PEFC is stopped, the fuel cell stack and the fuel cell stack are connected to each other in the gas supply side manifold of the fuel cell stack and in the fuel cell system. Water droplets are generated in the gas supply pipe due to condensation of the remaining humidified gas.

  During PEFC re-operation, the fuel cell stack gas supply side manifold contains water droplets that are generated at the time of stoppage and water droplets that are generated in the gas supply pipe at the time of stoppage and flow into the gas supply side manifold. Therefore, in order to obtain a stable output, it is necessary to send out these water droplets to the gas flow channel groove without staying in the manifold.

  That is, when water droplets stay in the gas supply side manifold, the water droplets block the connection portion between the manifold and the gas flow channel groove, obstructing the gas flow, and no gas is supplied to the MEA. As a result, it is known that the performance of the fuel cell stack is degraded, such as causing a flooding phenomenon and destabilizing the electric output.

Therefore, conventionally, a method has been disclosed in which an introduction portion is provided between the gas supply side manifold and the gas flow channel groove to improve the hydrophilicity of the introduction portion. (For example, see Patent Document 1)
Further, a method for improving the hydrophobicity of the introduction portion is disclosed. (For example, see Patent Document 2)

JP 2007-141695 A JP 2010-182488 A

However, in the configurations of Patent Document 1 and Patent Document 2, a process for suppressing the retention of water droplets is performed on the portion of the inner wall surface of the gas supply side manifold adjacent to the connection portion between the manifold and the gas flow channel groove. In other words, there was a possibility that water droplets in the gas supply side manifold would block the connection with the gas flow channel groove on the inner wall surface of the manifold. Therefore, it has been difficult to obtain a stable electric output at the start of PEFC.

  The present invention solves the above-mentioned conventional problems, and suppresses the retention of water droplets in the vicinity of the connection portion at the connection portion with the gas flow channel groove on the inner wall surface of the manifold, and the gas flow channel groove is blocked by the water droplet. An object of the present invention is to provide a fuel cell stack capable of improving the stability of electric output by suppressing the above.

  In order to solve the above-described conventional problems, the fuel cell stack according to the present invention performs hydrophilicity improving treatment on a portion of the inner wall surface of the gas supply side manifold adjacent to the connection portion between the manifold and the gas flow channel groove. Is.

  As a result, at the connection portion of the manifold inner wall surface with the gas flow channel groove, the retention of water droplets in the vicinity of the connection portion is suppressed, and the gas flow channel groove is prevented from being blocked by water droplets, thereby stabilizing the electrical output. Can be improved.

  According to the fuel cell stack of the present invention, even when water droplets are generated or flow into the manifold, the retention of water droplets in the vicinity of the connection portion is suppressed at the connection portion with the gas flow channel groove on the inner wall surface of the manifold. In addition, since the gas channel groove is prevented from being blocked by water droplets, the performance of the fuel cell can be stably secured.

1 is a schematic view and a perspective view showing a schematic configuration of a fuel cell stack according to Embodiment 1 of the present invention. FIG. Sectional drawing which shows schematic structure of the battery module which concerns on Embodiment 1 of this invention. The top view which shows the gas flow path pattern of the separator which concerns on Embodiment 1 of this invention. Sectional drawing of the fuel gas supply side manifold of the fuel cell stack according to Embodiment 1 of the present invention. Sectional drawing of the fuel gas supply side manifold of the stack for fuel cells which concerns on Embodiment 2 of this invention The top view which shows the gas flow path pattern of the separator which concerns on Embodiment 3 and Comparative Example 2 of this invention The top view which shows the gas flow path pattern of the separator which concerns on Embodiment 4 and Comparative Example 3 of this invention The schematic diagram which shows the form of the water droplet in the connection part of the manifold and gas flow path groove | channel which concerns on Embodiment 1 of this invention.

  The first invention includes an electrolyte membrane-electrode assembly formed by sandwiching a solid polymer electrolyte membrane between a pair of gas diffusion electrodes, and a gas flow channel groove that forms a gas flow channel by contacting the gas diffusion electrode. The fuel cell stack is formed by stacking a plurality of separators. In particular, the stack includes a manifold connected to one end on the upstream side of the plurality of gas flow channel grooves, and a portion of the inner wall surface of the manifold adjacent to a connection portion between the manifold and the gas flow channel groove Is characterized in that a hydrophilicity improving treatment is applied.

With this configuration, at the connection between the manifold inner wall surface and the gas flow channel groove, water droplets in the vicinity of the connection portion have a contact angle that is improved by hydrophilization improvement processing to a portion adjacent to the connection portion between the manifold and the gas flow channel groove. Since it becomes small and it becomes difficult to form a spherical shape, it is possible to suppress the retention of water droplets in the vicinity of the connection portion between the manifold inner wall surface and the gas flow channel groove. Therefore, the gas channel groove inlet connected to the inner wall surface of the manifold can be prevented from being blocked by water droplets, so that the performance of the fuel cell can be secured stably.

  According to a second invention, in the first invention, a hydrophilic material is disposed on a portion of the inner wall surface of the manifold adjacent to a connection portion between the manifold and the gas flow channel groove. Features.

  With this configuration, the same effect can be obtained as when the hydrophilicity improving process is performed directly in the vicinity of the connection portion with the gas flow channel groove on the inner wall surface of the manifold, and blockage of the gas flow channel groove by water droplets can be suppressed. The battery performance can be secured stably.

  According to a third invention, in any one of the first and second inventions, the manifold is arranged vertically above the gas flow path.

  With this configuration, the connection portion between the manifold inner wall surface and the gas flow channel groove is formed at a position close to the bottom surface of the manifold, and even when water droplets are likely to stay, the connection between the manifold inner wall surface and the gas flow channel groove. It is possible to suppress the retention of water droplets at the connection portion. Therefore, the gas channel groove inlet connected to the manifold can be prevented from being blocked by water droplets, so that the dead space in the outer peripheral portion where the manifold is arranged can be obtained by arranging the manifold vertically above the cell. The fuel cell stack can be stably ensured even in a fuel cell stack that is compactly designed.

  According to a fourth invention, in any one of the first to third inventions, the gas flow path groove extends vertically downward from the manifold.

  With this configuration, in the connection portion between the inner wall surface of the manifold and the gas flow channel groove, the gas flow channel groove extends in the vertical direction from the manifold, so that the gas flow channel groove extends in the horizontal direction from the manifold. Even in the gas channel groove pattern in which the gas channel groove inlet is easily closed by water droplets, the retention of water droplets at the connecting portion between the manifold inner wall surface and the gas channel groove can be suppressed. Therefore, the gas channel groove inlet connected to the manifold can be prevented from being blocked by water droplets, so in the fuel cell stack in which the gas channel groove pattern is formed without detouring from the manifold to the cell. In addition, the performance of the fuel cell can be secured stably.

  According to a fifth invention, in any one of the first to fourth inventions, at least a portion of the manifold adjacent to the connecting portion with the gas flow channel groove of the fuel gas supply side manifold is subjected to hydrophilicity improving treatment. It is characterized by being.

  With this configuration, since the gas supply amount is small compared to the oxidant gas and the ability to discharge water droplets in the manifold is low, the fuel gas supply side manifold is subjected to hydrophilicity improvement processing. Since it is possible to suppress the retention of water droplets at the connection portion with the gas flow channel groove, and therefore, it is possible to suppress the gas flow channel groove inlet portion connected to the manifold from being blocked by water droplets, the fuel The battery performance can be secured stably.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the same components as those of the above-described embodiments will be denoted by the same reference numerals, and detailed description thereof will be omitted. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
[Configuration of fuel cell]
Next, the configuration of the fuel cell stack 101 according to the first embodiment will be described with reference to FIG.

  Here, an internal manifold type stack will be described as an example of a general configuration, but the present invention is not limited to the internal manifold type stack, and the same effect can be obtained with an external manifold type stack.

  FIG. 1A is a schematic diagram showing a schematic configuration of the fuel cell stack 101, and FIG. 1B is a perspective view.

  As shown in FIG. 1A, the fuel cell stack 101 includes a cell stack 80 in which a plurality of cells 10 are stacked in the thickness direction, and end plates 81 and 82 disposed at both ends of the cell stack 80. And a fastener (not shown) for fastening the cell stack 80 and the end plates 81 and 82 in the stacking direction of the cells 10. In addition, an insulating plate 83 and a current collector plate 85 are disposed between the end plate 81 and the cell stack 80, and an insulating plate 84 and a current collector plate are disposed between the end plate 82 and the cell stack 80. 86 is arranged.

  As shown in FIG. 1B, the cell stack 80 includes a fuel gas supply side manifold 31, an oxidant gas supply side manifold 33, and a heat medium supply side manifold (not shown) so as to extend in the stacking direction of the cells 10. And are connected to a fuel gas supply port 41, an oxidant gas supply port 51, and a heat medium supply port (not shown), respectively. Further, a fuel gas discharge side manifold 32, an oxidant gas discharge side manifold 34, and a heat medium discharge side manifold (not shown) are configured, respectively, and a fuel gas discharge port, an oxidant gas discharge port, a heat medium discharge port, and the like. It is connected to an outlet (both not shown).

  Here, in order to design the fuel cell stack as compactly as possible, it is desirable to eliminate the dead space in the outer peripheral portion where the manifold is arranged. For this reason, the fuel gas supply side manifold, the oxidant gas supply side manifold, the heat medium supply side manifold, and the fuel gas discharge side manifold, the oxidant gas discharge side manifold, and the heat medium discharge side manifold are concentrated on two opposing surfaces. In general, the space is effectively used.

[Cell structure]
Next, the cell 10 of the fuel cell stack 101 according to the first embodiment will be described with reference to FIGS. 2 and 3.

  FIG. 2 is a cross-sectional view schematically showing a schematic configuration of the cell 10 in the fuel cell stack 101 shown in FIG. In FIG. 2, a part is omitted.

  As shown in FIG. 2, the cell 10 includes an MEA 18 (Membrane-Electrode-Assembly: membrane-electrode assembly), a gasket 19, an anode separator 16, and a cathode separator 17.

  The MEA 18 includes an electrolyte layer (polymer electrolyte membrane) 11 that selectively transports hydrogen ions, an anode 12, and a cathode 13. The electrolyte layer 11 has a substantially quadrangular shape, and an anode 12 and a cathode 13 are provided on both surfaces of the electrolyte layer 11 so as to be located inward from the peripheral edge thereof. The peripheral edge of the electrolyte layer 11 includes a fuel gas supply side manifold hole, an oxidant gas supply side manifold hole, a heat medium supply side manifold hole, a fuel gas discharge side manifold hole, an oxidant gas discharge side manifold hole, A heat medium discharge side manifold hole (both not shown) is provided so as to penetrate in the thickness direction.

  The anode 12 is provided on one main surface of the electrolyte layer 11, and is a catalyst-supported carbon made of carbon powder (conductive carbon particles) supporting a platinum-based metal catalyst (electrode catalyst) and a polymer attached to the catalyst-supported carbon. It has an anode catalyst layer containing an electrolyte and an anode gas diffusion layer (none of which is shown) having both gas permeability and conductivity. The anode catalyst layer is disposed so that one main surface is in contact with the electrolyte layer 11, and an anode gas diffusion layer is disposed on the other main surface of the anode catalyst layer. Similarly, the cathode 13 is provided on the other main surface of the electrolyte layer 11, and adheres to the catalyst-supporting carbon and the catalyst-supporting carbon made of carbon powder (conductive carbon particles) supporting the platinum-based metal catalyst (electrode catalyst). A cathode catalyst layer containing the polymer electrolyte, and a cathode gas diffusion layer (both not shown) provided on the cathode catalyst layer and having both gas permeability and conductivity.

  A pair of fluorine rubber doughnut-shaped gaskets 19 are disposed around the anode 12 and the cathode 13 of the MEA 18 with the electrolyte layer 11 interposed therebetween. This prevents the fuel gas, oxidant gas, and heat medium from leaking out of the battery, and prevents them from being mixed with each other in the cell 10. Note that the peripheral portion of the gasket 19 includes a fuel gas supply side manifold hole, an oxidant gas supply side manifold hole, a heat medium supply side manifold hole, a fuel gas discharge side manifold hole, and an oxidant, which are through holes in the thickness direction. A gas discharge side manifold hole and a heat medium discharge side manifold hole (both not shown) are provided.

  Further, a conductive anode separator 16 and a cathode separator 17 are disposed so as to sandwich the MEA 18 and the gasket 19. Thereby, MEA 18 is mechanically fixed, and when a plurality of cells 10 are stacked in the thickness direction, MEA 18 is electrically connected. The anode separator 16 and the cathode separator 17 can be a metal having excellent thermal conductivity and conductivity, graphite, or a mixture of graphite and a resin, such as carbon powder and a binder (solvent). A mixture prepared by injection molding or a plate of titanium or stainless steel plated with gold can be used.

  A groove-like fuel gas passage groove 14 through which fuel gas flows is provided on one main surface (hereinafter referred to as an inner surface) of the anode separator 16 that contacts the anode 12, and the other surface is provided on the other surface. A groove-like heat medium flow path groove 22 is provided for the heat medium to flow therethrough. Similarly, a groove-like oxidant gas flow channel 15 for allowing the oxidant gas to flow is provided on one main surface (hereinafter referred to as an inner surface) of the cathode separator 17 that contacts the cathode 13. On the other surface, a groove-like heat medium flow path groove 23 through which the heat medium flows is provided.

  3A is a plan view of the anode separator 16 in the fuel cell stack 101 shown in FIG. 1, and FIG. 3B is a plan view of the cathode separator 17 on the gas flow path side.

  At the periphery of each of the anode separator 16 and the cathode separator 17, a cathode inlet manifold 111 that supplies a fuel gas, an anode inlet manifold 113 that supplies an oxidant gas, a heat medium inlet manifold 112 that supplies a heat medium, and A manifold hole 114 for discharging fuel gas, an oxidant gas discharge side manifold hole 116, and a heat medium discharge side manifold 115 are provided so as to penetrate in the thickness direction. Further, the shape of the fuel gas channel groove 14 and the oxidant gas channel groove 15 is arbitrary. For example, the fuel gas channel groove 14 and the oxidant gas channel groove 15 may be formed in a serpentine shape as viewed from the thickness direction of the cell 10. It may be formed.

  Thereby, fuel gas and oxidant gas are supplied to the anode 12 and the cathode 13, respectively, and these gases react to generate electricity and heat.

  And the cell laminated body 80 is formed by laminating | stacking the cell 10 formed in this way in the thickness direction.

  As Embodiment 1, FIG. 4 shows a cross-sectional view of the fuel gas supply side manifold 31 of the fuel cell stack.

  Gas channel groove adjacent portion 25 adjacent to gas flow channel groove connecting portion 24 between fuel gas supply side manifold 31 and fuel gas flow channel groove 14 of cell stack 80 produced in the first embodiment, and oxidation A hydrophilic epoxy resin was applied to the portion adjacent to the connecting portion between the agent gas supply side manifold 33 and the oxidant gas flow channel groove 15 as a hydrophilicity improving process, to produce a fuel cell stack. In addition, the hydrophilicity improving treatment includes application or impregnation of metal oxide (alumina, silica, zeolite, etc.) or hydrophilic resin (epoxy, polyvinyl alcohol, polyethylene glycol, acrylic acid, etc.), and surface treatment (oxidation). , Treatment with acid, plasma, ultraviolet light, surfactant, etc.), and any means that improves hydrophilicity can be used.

(Embodiment 2)
As a second embodiment, a cross-sectional view of a fuel gas supply side manifold 31 of a fuel cell stack is shown in FIG.

  A hydrophilic resin tube 35 is disposed on the inner wall surface of the fuel gas supply side manifold 31 of the cell stack 80 manufactured in the first embodiment. Similarly, a hydrophilic epoxy resin tube was disposed on the inner wall surface of the oxidant gas supply side manifold 33 to produce a fuel cell stack. The hydrophilic material includes a hydrophilic resin (epoxy, polyvinyl alcohol, polyethylene glycol, acrylic acid, etc.) and a surface coated with a hydrophilic resin, or a surface treatment (oxidation, acid, plasma, ultraviolet light, Any material that has been treated with a surfactant or the like and that has improved hydrophilicity can be used.

(Embodiment 3)
As Embodiment 3, FIG. 6 shows gas flow path patterns of the anode separator 16a and the cathode separator 17a of the fuel cell stack.

  Except for the anode separator 16a and the cathode separator 17a, in the gas channel groove connection portion 24 between the fuel gas supply side manifold 31 and the fuel gas channel groove 14 of the cell stack 80 manufactured in the same manner as in the first embodiment. A hydrophilic epoxy resin is applied to the adjacent gas flow channel groove adjacent portion 25 and the portion adjacent to the connection portion between the oxidant gas supply side manifold 33 and the oxidant gas flow channel groove 15 to form a fuel cell stack. Produced.

(Embodiment 4)
FIG. 6 shows a gas flow path pattern of the anode separator 16b and the cathode separator 17b of the fuel cell stack manufactured in the first embodiment as the fourth embodiment.

  Except for the anode separator 16b and the cathode separator 17b, in the gas flow channel groove connecting portion 24 between the fuel gas supply side manifold 31 and the fuel gas flow channel groove 14 of the cell stack 80 manufactured in the same manner as in the first embodiment. A hydrophilic epoxy resin is applied to the adjacent gas flow channel groove adjacent portion 25 and the portion adjacent to the connection portion between the oxidant gas supply side manifold 33 and the oxidant gas flow channel groove 15 to form a fuel cell stack. Produced.

(Embodiment 5)
As the fifth embodiment, adjacent to the gas flow channel groove adjacent to the gas flow channel groove connecting portion 24 between the fuel gas supply side manifold 31 and the fuel gas flow channel groove 14 of the cell stack 80 manufactured in the first embodiment. The part 25 was coated with a hydrophilic epoxy resin to produce a fuel cell stack.

  As Comparative Example 1, a portion 25 adjacent to the connection portion 24 between the fuel gas supply side manifold 31 and the fuel gas flow channel groove 14 of the cell stack 80 manufactured in the first embodiment, and the oxidant gas supply side A fuel cell stack was produced without subjecting the portion adjacent to the connecting portion between the manifold 33 and the oxidant gas flow channel groove 15 to the hydrophilicity improving process.

  As Comparative Example 2, FIG. 6 shows gas flow path patterns of the anode separator 16a and the cathode separator 17a of the fuel cell stack.

  Except for the anode separator 16a and the cathode separator 17a, a portion 25 adjacent to the connection portion 24 between the fuel gas supply side manifold 31 and the fuel gas flow channel groove 14 of the cell stack 80 manufactured in the same manner as in the first embodiment. And the stack for fuel cells was produced, without performing a hydrophilicity improvement process to the part adjacent to the connection part of the oxidizing agent gas supply side manifold 33 and the oxidizing agent gas flow path groove 15.

  As Comparative Example 3, FIG. 7 shows gas flow path patterns of the anode separator 16b and the cathode separator 17b of the fuel cell stack manufactured in the first embodiment.

  Except for the anode separator 16b and the cathode separator 17b, a portion 25 adjacent to the connection portion 24 between the fuel gas supply side manifold 31 and the fuel gas flow channel groove 14 of the cell stack 80 manufactured in the same manner as in the first embodiment. And the stack for fuel cells was produced, without performing a hydrophilicity improvement process to the part adjacent to the connection part of the oxidizing agent gas supply side manifold 33 and the oxidizing agent gas flow path groove 15.

  As Comparative Example 4, a hydrophilic epoxy resin is applied to a portion of the cell stack 80 manufactured in Embodiment 1 adjacent to the connecting portion between the oxidizing gas supply side manifold 33 and the oxidizing gas channel groove 15. Thus, a fuel cell stack was produced.

  The fuel cell stacks produced in Comparative Examples 1 to 5 were generated for 24 hours, stopped for 24 hours in an environment of 5 ° C., and then flooded when restarted, and after 12 hours to 24 hours after restart. The electrical output stability was evaluated based on the difference between the cell voltages.

  Table 1 shows the results of evaluating the electrical output stability of the fuel cell stack.

  Comparative Example 1 includes a portion 25 adjacent to the connection portion 24 between the fuel gas supply side manifold 31 and the fuel gas flow channel groove 14 and a connection portion between the oxidant gas supply side manifold 33 and the oxidant gas flow channel groove 15. The hydrophilicity improving process is not performed to the part adjacent to. According to the fuel cell stack of the first embodiment, since there is no flooding and each cell voltage difference is small even when compared with Comparative Example 1, the fuel cell stack according to Embodiment 1 is connected to the gas flow channel groove on the inner wall surface of the manifold. It is considered that there is an effect of suppressing the retention of water droplets in the vicinity of the connection portion and suppressing the gas channel groove from being blocked by water droplets.

  FIG. 8 shows the form of water droplets at the connection between the manifold and the gas flow channel. FIG. 8A is a schematic cross-sectional view in the vertical direction of the manifold when the hydrophilization improving process is performed on a portion adjacent to the connection portion between the manifold and the gas flow channel groove. FIG. 8B is a schematic cross-sectional view in the vertical direction of the manifold when the portion adjacent to the connection portion between the manifold and the gas flow channel groove is not subjected to the hydrophilization improving process. FIG. 8C is a schematic cross-sectional view in the horizontal direction of the manifold in the case where the portion adjacent to the connecting portion between the manifold and the gas flow channel groove is subjected to the hydrophilization improving process. FIG. 8D is a schematic cross-sectional view in the horizontal direction of the manifold in the case where the portion adjacent to the connection portion between the manifold and the gas flow channel groove has not been subjected to the hydrophilization improving process.

  From FIG. 8, it is difficult to form a spherical shape by reducing the contact angle of water droplets in the vicinity of the connecting portion due to the hydrophilization improving process at the connecting portion between the manifold inner wall and the gas flow channel groove adjacent to the connecting portion. Therefore, it is considered that the retention of water droplets at the connection portion between the manifold inner wall and the gas flow channel groove is suppressed, leading to the stability of the electric output.

  From Table 1, the fuel cell stack of Embodiment 2 has no flooding and a small cell voltage difference even when compared with Comparative Example 1, so that the gas flow channel groove inlet connected to the manifold is It is thought that there exists an effect which suppresses obstruction | occlusion with a water droplet.

  Moreover, the same effect is acquired compared with Embodiment 1 which apply | coated the hydrophilic epoxy resin as a hydrophilic improvement process.

This is because even when a hydrophilic material is disposed in a portion adjacent to the connecting portion between the manifold and the gas flow channel groove, the same effect as that obtained when the hydrophilicity improving treatment is directly applied to the adjacent portion can be obtained. It is thought that the blockage of the road groove by water droplets can be suppressed, which led to electrical output stability.

  As shown in Table 1, the fuel cell stack according to the third embodiment has the same electrical output stability as compared with the first embodiment in which the supply-side manifold is arranged vertically above the MEA.

  This is because the portion 25 adjacent to the connection portion 24 between the fuel gas supply side manifold 31 and the fuel gas flow channel groove 14 and the connection portion between the oxidant gas supply side manifold 33 and the oxidant gas flow channel groove 15 are connected. When hydrophilicity-improving treatment is applied to the adjacent part, it is considered that the gas channel groove can be prevented from being clogged with water droplets regardless of the position of the manifold with respect to the MEA, leading to electrical output stability. .

  On the other hand, from Table 1, when compared with Comparative Example 1 in which the manifold is disposed vertically above the MEA and Comparative Example 2 in which the manifold is disposed in the horizontal horizontal direction of the MEA, the supply-side manifold is disposed vertically above the MEA. Since Comparative Example 1 has a larger cell voltage difference, a result of low electrical output stability is obtained.

  This is because the dead space in the outer peripheral part where the manifold is arranged is eliminated, and the fuel cell stack is designed in a compact manner. In this case, the supply side manifold is arranged vertically above the MEA. It is considered that the effect of the hydrophilicity improvement treatment can be obtained more than that, and the blockage of the gas channel groove by the water droplets can be suppressed, leading to the stability of the electric output.

According to the fuel cell stack of the fourth embodiment, as shown in Table 1, the same electric output stability is obtained as compared with the first embodiment in which the gas flow channel groove extends in the vertical direction from the supply side manifold. .
This is because the portion 25 adjacent to the connection portion 24 between the fuel gas supply side manifold 31 and the fuel gas flow channel groove 14 and the connection portion between the oxidant gas supply side manifold 33 and the oxidant gas flow channel groove 15 are connected. When the hydrophilicity improving treatment is applied to the adjacent part, it is possible to suppress the blockage of the gas flow channel groove by water droplets regardless of the extending direction of the gas flow channel groove, which leads to electrical output stability it is conceivable that.

  Comparative Example 1 includes a portion 25 adjacent to the connection portion 24 between the fuel gas supply side manifold 31 and the fuel gas flow channel groove 14 and a connection portion between the oxidant gas supply side manifold 33 and the oxidant gas flow channel groove 15. The portion adjacent to the surface is not subjected to the hydrophilicity improving process, and the gas flow path groove extends in the vertical direction from the supply side manifold. From Table 1, comparing Comparative Example 1 and Comparative Example 3 in which the gas flow channel groove extends in the horizontal direction from the supply side manifold, Comparative Example 1 in which the gas flow channel groove is extended in the vertical direction Since each cell voltage difference is large, a result with low electrical output stability is obtained.

  This eliminates the dead space in the outer peripheral portion where the manifold is arranged, and enables the fuel cell stack to be designed in a compact manner. In addition, when the supply manifold is arranged vertically above the cell and the flow path length from the supply manifold to the cell is minimized, the gas channel groove extends in the vertical direction. It is considered that the effect of the hydrophilicity improvement treatment is obtained more than in the case of stretching, the blockage of the gas flow channel groove by water droplets can be suppressed, and the electrical output stability is led.

From Table 1, the fuel cell stack of the fifth embodiment is subjected to hydrophilicity improving processing on the portion 25 adjacent to the connection portion 24 between the fuel gas supply side manifold 31 and the fuel gas flow channel groove 14. . However, compared with the comparative example 4 in which the hydrophilicity improving process is not performed on the portion adjacent to the connection portion between the oxidant gas supply side manifold 33 and the oxidant gas flow channel groove 15, the flooding resistance is the same. Therefore, a result in which each cell voltage difference is small is obtained.

  This is a portion adjacent to the connecting portion 24 between the fuel gas supply side manifold 31 and the fuel gas flow channel groove 14 where the gas supply amount is small compared to the oxidant gas and the ability to discharge water droplets in the manifold is low. 25, it is considered that the hydrophilicity-improving treatment can suppress the retention of water droplets at the connecting portion between the manifold inner wall and the gas flow channel groove, leading to electrical output stability.

  In the fuel cell stack according to the first embodiment configured as described above, the retention of water droplets is suppressed at the connection portion between the supply side manifold inner wall and the gas flow channel groove, and the electrical output stability can be improved. It is possible to stably ensure the performance of the fuel cell.

  As described above, the fuel cell stack according to the present invention is effective in suppressing the blockage of the gas channel groove by water droplets even in the state where water droplets are generated or flow into the supply-side manifold. In addition, it is difficult to be affected by flooding or the like caused by water droplets staying at the connection portion between the inner wall surface of the supply side manifold and the gas flow path groove. Thereby, it can apply to uses, such as a fuel cell using a polymer type solid electrolyte, a fuel cell device, and a stationary fuel cell cogeneration system, where electrical output stability is required.

DESCRIPTION OF SYMBOLS 10 Cell 11 Electrolyte layer 12 Anode 13 Cathode 14 Fuel gas flow path groove 15 Oxidant gas flow path groove 16, 16a, 16b Anode separator 17, 17a, 17b Cathode separator 18 Membrane-electrode assembly 19 Gasket 22, 23 Heat medium flow Channel groove 24 Gas channel groove connection portion 25 Gas channel groove adjacent portion 31 Fuel gas supply side manifold 32 Fuel gas discharge side manifold 33 Oxidant gas supply side manifold 34 Oxidant gas discharge side manifold 35 Hydrophilic resin tube 36 Hydrophilic Improved processed manifold 37 Hydrophilic improved unprocessed manifold 38, 39 Water droplet 40 Gas channel groove 41 Fuel gas supply port 51 Oxidant gas supply port 85, 86 Current collector plate 80 Cell stack 81, 82 End plate 83, 84 Insulation Plate 101 Fuel cell stack 111 Cathode inlet manifold Rudo 112 heat medium inlet manifold 113 anode inlet manifold 114 manifold aperture

Claims (5)

An electrolyte membrane-electrode assembly in which a solid polymer electrolyte membrane is sandwiched between a pair of gas diffusion electrodes, and a separator having a gas flow channel groove that forms a gas flow channel by contacting the gas diffusion electrode, respectively. In a fuel cell stack formed by stacking a plurality of layers,
The stack includes a manifold connected to one end on the upstream side of the plurality of gas flow channel grooves,
A fuel cell stack, wherein a hydrophilicity-improving treatment is applied to a portion of the inner wall surface of the manifold adjacent to a connection portion between the manifold and the gas flow channel groove. 2. The fuel cell according to claim 1, wherein a hydrophilic material is disposed on a portion of the inner wall surface of the manifold adjacent to a connection portion between the manifold and the gas flow path groove. stack.   3. The fuel cell stack according to claim 1, wherein the manifold is disposed vertically above the gas flow path.   The fuel cell stack according to claim 1, wherein the gas flow path groove extends vertically downward from the manifold.   The hydrophilicity improving process is performed to the part adjacent to the connection part with the said gas flow path groove | channel of the manifold of the fuel gas supply side among the said manifolds, The any one of Claims 1-4 characterized by the above-mentioned. A fuel cell stack according to claim 1.