JP2019121431A - Fuel cell stack - Google Patents

Abstract

To maintain power generation performance for a fuel battery cell in a situation in which the fuel battery stack inclines.SOLUTION: In at least part of an area of a bottom edge of a gas manifold formed, via a stack of fuel battery cells, by a separator-side manifold hole of both separators sandwiching, in an outer edge area of a film electrode joined body, the film electrode joined body, surrounded by a frame-like resin sheet, together with the resin sheet and a sheet-side manifold hole of the resin sheet, the leading end of the resin sheet is located further inside the gas manifold than the leading ends of both the separators. Both the separators define a clearance recess in at least one sheet surface of the resin sheet on the bottom edge side of the gas manifold. The resin sheet has a gas supply/discharge passage for supplying/discharging gas from the clearance recess to the film electrode joined body. At least either both the separators surrounding the clearance recess or the resin sheet is hydrophilic in an area surrounding the clearance recess.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a fuel cell stack.

  The fuel cell stack is configured by stacking a plurality of fuel cells, and each fuel cell sandwiches the membrane electrode assembly between the cathode separator and the anode separator. In sandwiching a membrane electrode assembly with a separator, a method has been proposed in which the membrane electrode assembly is sandwiched between a cathode sheet and an anode sheet separator together with a resin sheet after the membrane electrode assembly is surrounded by a frame-shaped resin sheet. (For example, patent document 1).

JP, 2015-88293, A

  The fuel cell stack is installed so that the stacking direction of the fuel cells is in a horizontal posture, but the fuel cell stack is not always in the horizontal posture. For example, in a fuel cell mounted on a moving object such as a vehicle, one end side in the cell stacking direction, for example, the front end of the fuel cell stack is lower in the traveling process of the vehicle on an inclined road or the parking process on an inclined parking road. The fuel cell stack may be inclined such that the rear end of the fuel cell stack on the other end side in the cell stacking direction is up. In such an inclined posture, since the manifold for supplying / discharging fuel gas / oxidizing gas which penetrates the fuel cell stack in the cell stacking direction in the outer edge region of the membrane electrode assembly is also inclined, water reaching the manifold, specifically, generated water Also, water (specifically, water vapor) that has permeated through the electrolyte membrane or gas-containing water may be stored along the manifold at the lower side of the slope. Thus, if water is stored in the manifold, gas supply and discharge through the manifold in the fuel cell on the lower side of the slope where water is stored may be inhibited, and the power generation performance of the fuel cell may not be maintained. The same applies to the case where the fuel cell stack is inclined so that the rear end of the fuel cell stack is at the bottom and the front end of the fuel cell is at the top. For these reasons, it has been required to maintain the power generation performance of the fuel cell under the condition where the fuel cell stack is inclined.

  The present invention has been made to solve at least a part of the above-mentioned problems, and can be realized as the following modes.

(1) According to one aspect of the present invention, a fuel cell stack is provided. In this fuel cell stack, a plurality of fuel cells are formed by sandwiching a membrane electrode assembly surrounded by a frame-shaped resin sheet together with the resin sheet between the cathode side and anode side separators in the outer edge region of the membrane electrode assembly. Fuel cell stack, wherein a separator side manifold hole provided in the outer edge area of the two separators and a sheet side manifold hole provided in the outer edge area of the resin sheet are stacked layers of the fuel cells Thus, the gas manifold is formed, and in at least a partial region of the bottom side of the gas manifold, the front end of the resin sheet is positioned inside the gas manifold from the front ends of the two separators. Then, both separators form a gap recess in at least one sheet surface of the resin sheet on the bottom side of the gas manifold, and the resin sheet is formed from the gap recess into the membrane electrode assembly And at least one of the separators and the resin sheet surrounding the gap recess has hydrophilicity in the surrounding area of the gap recess.

  In the fuel cell stack of this embodiment, even if water reaches the gas manifold formed by the sheet side manifold hole and the separator side manifold hole, this water is a resin sheet in at least a partial region of the bottom of the gas manifold. The water is retained in the gap recess in the sheet surface of the sheet, and this water retention state is maintained by the resin sheet whose tip is located inside the gas manifold. The water thus retained is introduced to the membrane electrode assembly through the gas supply / discharge passage of the resin sheet. In the fuel cell stack of this embodiment, the above-described water retention is performed in each of the stacked fuel cells, so the front end of the fuel cell stack is lower in the cell height direction perpendicular to the fuel cell stacking direction. Even if the fuel cell stack is inclined so that the rear end of the fuel cell stack is at the top, it is possible to suppress the occurrence of a situation where excessive water is accumulated on the side of the front end of the fuel cell stack. The same applies to the case where the fuel cell stack is inclined so that the rear end of the fuel cell stack is below and the front end of the fuel cell stack is above. Therefore, according to the fuel cell stack of this aspect, it is possible to maintain the power generation performance of the fuel cell even under a situation where the fuel cell stack is inclined.

  The present invention can be realized in various aspects. For example, it can be realized in the form of a method of manufacturing a fuel cell stack, a fuel cell, or a method of manufacturing the same.

It is an explanatory view showing a schematic structure of a fuel cell comprised from a fuel cell concerning an embodiment of the present invention. FIG. 2 is an explanatory view showing a fuel cell in an embodiment of the present invention in a disassembled state. It is an explanatory view expanding and showing the important section of the manifold by the side of air out in a fuel cell. FIG. 5 is an explanatory view showing the manifold in cross section along line 4-4 in FIG. 3 in a state where a plurality of fuel cells are stacked; FIG. 5 is an explanatory view showing the manifold in cross section along line 5-5 in FIG. 3 in a state where a plurality of fuel cells are stacked; FIG. 6 is an explanatory view showing the manifold in cross section along line 6-6 in FIG. 3 in a state where a plurality of fuel cells are stacked; It is explanatory drawing which shows typically the condition where the fuel cell inclined so that the fuel cell front end of a fuel cell might become a perpendicular downward. FIG. 5 is an explanatory view showing a cross section of a manifold corresponding to FIG. 4 in a state where a plurality of fuel cells of the first modification are stacked. FIG. 5 is an explanatory view showing the manifold as viewed in a section corresponding to FIG. 4 in a state where a plurality of fuel cells of the second modification are stacked.

  FIG. 1 is an explanatory view showing a schematic configuration of a fuel cell 100 configured from a fuel cell 110 according to an embodiment of the present invention. The fuel cell 100 is configured by sandwiching a fuel cell stack in which a plurality of fuel cells 110 are stacked, between a pair of end plates 170F and 170E. The fuel cell 100 has a terminal plate 160F with an insulating plate 165F interposed between the end plate 170F on one end side thereof and the fuel cell 110. Hereinafter, for convenience, one end side of the fuel cell 100 in which the end plate 170F is disposed is referred to as a front end side, and the other end side on the right side of the drawing in the drawing is referred to as a rear end side.

  Similarly, between the end plate 170E on the rear end side and the fuel cell 110, the fuel cell 100 also has a terminal plate 160E on the rear end side with the insulating plate 165E on the rear end side interposed. The fuel cells 110, the terminal plates 160F and 160E, the insulating plates 165F and 165E, and the end plates 170F and 170E each have a plate structure having a substantially rectangular outer shape, and the long side is in the x-axis direction ( In the horizontal direction, the short side is disposed along the y-axis direction (vertical direction, vertical direction). The fuel cell 110 is stacked along the z-axis direction between end plates on the front end side and the rear end side, and the fuel cell 100 has a horizontal stacking direction (z-axis direction) of the fuel cell 110 as illustrated. It is installed in a vehicle etc. so that it will become a horizontal posture which overlaps in direction.

  The fuel cell 100 includes an air supply manifold 116 and an exhaust manifold 117, which are oxidizing gases containing oxygen, on the side of the end plate 170E on the rear end side. Further, each of the fuel cells 110 guides the air sent from the supply manifold 116 to the inside of the cell and the adjacent cells, and discharges the excess air having passed through the inside of the cell to the discharge manifold 117. That is, air is fed from the end plate 170E side and supplied to each cell, and then returned from the fuel cell 110 on the end plate 170F side, and the surplus is generated from the exhaust manifold 117 of the end plate 170E. Discharged with water.

  The fuel cell 100 includes a supply manifold 118 for supplying hydrogen gas as a fuel gas and a discharge manifold 119 on the side of the end plate 170F on the front end side. Then, each fuel cell 110 guides the hydrogen gas sent from the supply manifold 118 to the inside of the cell and the adjacent cells, and discharges the excess hydrogen gas that has passed through the cell to the discharge manifold 119. Therefore, hydrogen gas is fed from the end plate 170F side, returned from the fuel cell 100 on the end plate 170E side, and the surplus is discharged from the exhaust manifold 119 of the end plate 170F. A supply / discharge manifold is provided only on one side of the end plate 170F or end plate 170E, and reaction gas (hydrogen gas, air) and cooling water are supplied from the end plate 170F to the respective fuel cells 110, respectively. The exhaust gas and the exhaust water from the fuel cells 110 of the fuel cell may be discharged to the end plate 170E or the end plate 170F. The above-mentioned supply manifold 116 and the like are manifolds outside the cell and communicate with the gas manifold 30 in the cell described later. Although the fuel cell 100 also has a cooling water supply / discharge manifold, this cooling water supply / discharge manifold is not directly related to the subject matter of the present invention, and therefore, the illustration thereof is omitted in FIG.

  The terminal plate 160F on the front end side and the terminal plate 160E on the rear end are current collector plates of the generated power of each fuel cell 110, and output the power collected from a current collector terminal (not shown) to the outside.

  FIG. 2 is an explanatory view showing the fuel cell 110 in an embodiment of the present invention in a disassembled state. The fuel cell 110 is a solid polymer fuel cell that receives supply of hydrogen and oxygen to generate electric power. The fuel cell 110 includes the power generation body 10, the resin sheet 20, the separator 40a on the cathode side, and the separator 40b on the anode side.

  The power generation body 10 includes an electrolyte membrane (not shown), a catalyst layer (not shown) formed adjacent to both sides of the electrolyte membrane, and a gas diffusion layer (not shown). The electrolyte membrane is a solid polymer thin film showing good proton conductivity in the wet state. The electrolyte membrane is constituted of, for example, an ion exchange membrane of fluorine resin. The catalyst layer comprises a catalyst that promotes a chemical reaction of hydrogen and oxygen, and carbon particles supporting the catalyst. And a membrane electrode assembly (MEA: Membrane Electrode Assembly) is obtained by forming a catalyst layer on both membrane surfaces of an electrolyte membrane.

  The gas diffusion layers are respectively provided adjacent to the surface on the catalyst layer side. The gas diffusion layer is a layer for diffusing the reaction gas used for the electrode reaction along the surface direction of the electrolyte membrane, and is made of a porous diffusion layer base material. As a base material for the diffusion layer, a porous base material having conductivity and gas diffusivity, such as a carbon fiber base material, a graphite fiber base material, a foam metal, etc., is used. The electrolyte membrane, the catalyst layer, and the gas diffusion layer are collectively referred to as a membrane electrode gas diffusion layer assembly (MEGA: Membrane Electrode Gas-diffusion-layer Assembly).

  The resin sheet 20 is a frame-shaped resin member that surrounds the entire area around the power generation body 10 including the membrane electrode assembly. In the present embodiment, for example, polyethylene terephthalate (PET) is used as the resin member. However, various other thermoplastic resin members such as polypropylene and polyethylene can also be used as the resin member. The resin sheet 20 is provided with an opening 21 surrounding the power generation body 10 in the central region and housed therein. The sheet side manifold holes 30 a and the cooling are provided on both sides of the opening 21, specifically, on both sides of the opening 21 along the x-axis direction. And a manifold hole 31. The sheet side manifold holes 30a are formed side by side vertically in the y-axis direction, and the sheet side manifold holes 30a are the aforementioned supply manifold 116 and discharge manifold 117 for the reaction gas (hydrogen gas, air). It overlaps with one of the supply manifold 118 and the discharge manifold 119, and the reaction gas flows in the direction (z-axis direction) that penetrates the resin sheet 20. The cooling manifold hole 31 overlaps with a cooling water supply / discharge manifold (not shown in FIG. 1), and the cooling water flows in a direction (z-axis direction) which penetrates the resin sheet 20.

  The resin sheet 20 is provided with a plurality of gas supply and discharge paths 50 between the sheet side manifold hole 30 a and the opening 21. The gas supply / discharge passage 50 is formed as a sheet through hole of a long diameter of a linear path along the x-axis direction, and is a gas passage for gas supply / discharge from the sheet side manifold hole 30a to the membrane electrode assembly of the power generation body 10. is there. The gas supply and discharge passage 50 may be a groove-shaped gas supply and discharge passage having a long groove shape. In this case, by forming the gas supply / discharge passage 50 as a sheet through hole, the thickness of the resin sheet 20, and in other words, the thickness of the fuel cell 110, is made thinner than that of the grooved gas supply / discharge passage. be able to.

  In addition, the resin sheet 20 has hydrophilicity in the area where the sheet-side manifold holes 30 a are formed, that is, the sheet surface in the outer edge area of the power generation body 10. That is, the resin sheet 20 is subjected to hydrophilicity-imparting treatment such as plasma irradiation, chemical vapor deposition, ultraviolet irradiation, or etching on the surface of the resin member described above in the outer edge region of the power generation body 10 and is hydrophilic on the sheet surface of at least the outer edge region. Have sex. In the process of manufacturing the resin sheet 20, the entire surface of the resin sheet 20 may be subjected to hydrophilicity imparting treatment. Besides, the resin sheet 20 itself may be molded using a hydrophilic resin member.

  The pair of separators 40a and 40b are laminated on the resin sheet 20 so as to sandwich the resin sheet 20 and the power generating body 10 including the membrane electrode assembly in the outer edge region of the power generating body 10. The two separators of the separators 40a and 40b are formed, for example, by press-forming a metal plate made of stainless steel, titanium, or an alloy thereof. Therefore, the separators 40a and 40b have hydrophilicity on their surfaces.

  In the present embodiment, the separator 40 a is a cathode side separator, and the separator 40 b is an anode side separator. Then, both separators of the separators 40 a and 40 b have separator-side manifold holes 30 b and cooling manifold holes 31 in the outer edge region of the power generation body 10. The cooling manifold holes 31 overlap the cooling manifold holes 31 of the resin sheet 20, and the cooling water flows in a direction (z-axis direction) passing through both the separators 40a and 40b. Although the separators 40a and 40b form an inter-cell cooling flow passage between the overlapping fuel cells 110, the inter-cell cooling flow passage is not directly related to the subject matter of the present invention. Is omitted.

  The separator side manifold holes 30 b are used for supplying and discharging the reaction gas (hydrogen gas, air) to the membrane electrode assembly of the power generation body 10, and overlap with the sheet side manifold holes 30 a of the resin sheet 20. In the present embodiment, the opening area of the sheet side manifold hole 30a is smaller than the opening area of the separator side manifold hole 30b. In the present embodiment, hereinafter, a manifold formed by overlapping the sheet side manifold hole 30 a and the separator side manifold hole 30 b is referred to as a gas manifold 30.

  Both separators of the separators 40a and 40b are provided with a flow path 41 by passing from the separator side manifold hole 30b on the in side of the reaction gas (hydrogen gas, air) to the separator side manifold hole 30b on the out side. The flow path 41 is formed by the unevenness of the separators 40a and 40b, and has a plurality of flow path configurations branched from the distribution flow path 42 in the vicinity of the in-side separator side manifold hole 30b. And the flow path 41 merges in the vicinity of the separator side manifold hole 30b of the out side, and makes the merging flow path 43. As shown in FIG. The distribution flow path 42 overlaps and communicates with the gas supply / discharge path 50 of the resin sheet 20 in the vicinity of the separator side manifold hole 30b on the in side, and the merging flow path 43 is a resin in the vicinity of the separator side manifold hole 30b on the out side It overlaps and communicates with the gas supply and discharge passage 50 of the sheet 20. As a result, the reaction gas (hydrogen gas, air) that has flowed into the in-side separator side manifold hole 30 b and the sheet side manifold hole 30 a of the resin sheet 20 overlapping it is distributed from the gas supply / discharge passage 50 of the resin sheet 20 The flow passes through a plurality of flow paths 41 passing through 42 and supplied to the power generation body 10. The reaction gas (hydrogen gas, air) that has passed through the flow path 41 passes through the gas supply and discharge path 50 from the merging flow path 43, and the separator side manifold hole 30b on the out side and the sheet side manifold of the resin sheet 20 overlapping this. It is discharged from the hole 30a.

  FIG. 3 is an enlarged view of the main part of the gas manifold 30 on the air-out side of the fuel cell 110. This main part is an area indicated by an A in the figure with respect to the separator side manifold holes 30b of the separators 40a and 40b shown in FIG. 2 and the sheet side manifold holes 30a of the resin sheet 20. FIG. 4 is an explanatory view showing the gas manifold 30 in cross section along line 4-4 in FIG. 3 in a state where a plurality of fuel cells 110 are stacked. FIG. 5 is an explanatory view showing the gas manifold 30 in cross section along line 5-5 in FIG. 3 in a state where a plurality of fuel cells 110 are stacked. 6 is an explanatory view showing the gas manifold 30 in cross section along line 6-6 in FIG. 3 in a state where a plurality of fuel cells 110 are stacked.

  As shown in FIG. 3, the sheet-side manifold hole 30a of the resin sheet 20 and the separator-side manifold holes 30b of the separators 40a and 40b overlap to form a gas manifold 30, and around the manifold, the cathode is viewed from the top of the drawing The separator 40a on the side, the resin sheet 20, and the separator 40b on the anode are in a stacked state. Further, as described above, since the opening area of the sheet side manifold hole 30a of the resin sheet 20 is smaller than the opening area of the separator side manifold hole 30b, the tip end of the resin sheet 20 at the bottom of the gas manifold 30 Are located on the inner side of the gas manifold 30 from the tips of the separators on the anode side and the cathode side. That is, as shown in FIG. 4, the bottom wall surface 30at of the sheet side manifold hole 30a protrudes from the bottom wall surface 30bt of the separator side manifold hole 30b in the cell height direction (y axis direction) perpendicular to the cell stacking direction. Get higher. Further, as shown in FIGS. 5 and 6, the side wall surface 30as of the sheet side manifold hole 30a protrudes from the side wall surface 30bs of the separator side manifold hole 30b along the horizontal direction (x-axis direction).

  The separators 40a and 40b are bent around the hole peripheral wall of the separator side manifold hole 30b away from the resin sheet 20, and as shown in FIG. 4, the side wall surface 30as of the bottom wall surface 30at of the sheet side manifold hole 30a A gap recess 23 is formed on the front and back sheet surfaces of the resin sheet 20 on the side. The gap recess 23 is a recess in which the bottom side of the recess is inclined, and in the single fuel cell 110, it is a recess to the bottom wall surface 30bt or the side wall surface 30bs of the separators 40a and 40b. On the other hand, when the fuel cells 110 are stacked, they are formed as a recess to the bottom wall surface 30 at or the side wall surface 30 as of the resin sheet 20. In the fuel cell 110 of this embodiment, the gap recess 23 is about 1.2 mm, and the protrusion of the resin sheet 20 is about 0.8 mm in depth, in order to maintain the liquid water in the gap recess 23. Thus, it is possible to provide a water retention space of about 2.0 mm as the gap recess 23 in a state where the fuel cells 110 are stacked. Since the separators 40a and 40b forming the space recess 23 have hydrophilicity on the surface, and the resin sheet 20 having the space recess 23 on the sheet surface has hydrophilicity through the hydrophilicity imparting treatment, the fuel cell The cell 110 will exhibit hydrophilicity in the surrounding area of the recess 23. The depth dimension of the above-described gap recess 23 may be appropriately set according to the inter-cell pitch, the size of the gas manifold 30, or the maximum gas supply / discharge amount of the reaction gas, and is limited to the above-mentioned dimension numerical value. Do not mean.

  The gas supply / discharge path 50 of the resin sheet 20 overlaps the separators 40a and 40b except for the gas introduction portion 51 in the vicinity of the sheet-side manifold hole 30a. Among the separators 40a and 40b, as shown in FIG. 2, the separator 40a on the cathode side has a merging channel 43 near the separator-side manifold hole 30b, and this merging channel 43 is as shown in FIG. And the gas supply and discharge passage 50. Therefore, the gas supply / discharge passage 50 participates in the air discharge in the fuel cell 110 in the air-out gas manifold 30 shown in FIG. 3 between the cathode side separator 40 a and the resin sheet 20. On the other hand, since the separator 40b on the anode side does not have the merging passage 43 in the vicinity of the separator-side manifold hole 30b, the gas supply / discharge passage 50 does not participate in the gas supply / discharge. The involvement of the gas supply and discharge path 50 in the gas supply and discharge is the same as in the in-side gas manifold 30 for air and the in-out gas manifold 30 for hydrogen gas. The hydrogen gas flowing into the in-side gas manifold 30 by the involvement of the gas supply / discharge path of the gas supply / discharge path 50 passes through the flow path 41 of the anode side separator 40 b to join the membrane electrode of the power generation body 10 It is supplied to the body and discharged from the out-side gas manifold 30. Further, the air flowing into the in-side gas manifold 30 passes through the flow path 41 of the cathode side separator 40a, is supplied to the membrane electrode assembly of the power generation body 10, and is discharged from the out-side gas manifold 30. Ru. As described above, the resin sheet 20 according to the present embodiment has the gas supply / discharge passage 50 involved in the gas supply / discharge in the cell height direction (the bottom wall surface 30bt of the separator side manifold hole 30b) as shown in FIG. In the y-axis direction), the lower position is provided.

  A gasket 60 surrounding the gas manifold 30 is provided between the adjacent fuel cell 110 between the separator 40 a of one fuel cell 110 and the separator 40 b of the other fuel cell 110. The gasket 60 is bonded to the separator 40 a and seals the gas manifold 30 between the cells by stacking the fuel cells 100. The gasket 60 is formed of, for example, silicone rubber. A cooling flow passage through which the cooling water flows from the cooling manifold hole 31 is formed between the adjacent fuel cells 110, and even in this cooling flow passage, the cooling passage is sealed by the gasket 60.

  The fuel cells 110 according to the present embodiment described above use the water W for the gas even if the water W temporarily reaches the overlapping sheet side manifold hole 30a and separator side manifold hole 30b so as to constitute the gas manifold 30. At the bottom side of the manifold 30, water is retained in the gap recess 23 in the front and back sheet surfaces of the resin sheet 20. Then, the water retention state is maintained by the resin sheet 20 whose front end is positioned at the bottom of the gas manifold 30. In addition to this, since the fuel cell 110 of the present embodiment makes the resin sheet 20 surrounding the gap recess 23 and the separators 40a and 40b hydrophilic, the water retention state of the water W in the gap recess 23 can be made more reliably. Hold. Then, the fuel cell 110 of the present embodiment passes the water W held in the gap recess 23 through the gas supply / discharge passage 50 on the lower side (−y-axis direction) in the vertical direction shown in FIG. It leads to the membrane electrode assembly of electric power generation body 10 from the confluence | merging flow path 43 and the flow path 41 which are shown to. Since the fuel cells 100 in which the fuel cells 110 are stacked perform individual water holding and holding of the water holding state in each of the fuel cells 110, the effects described below are exhibited.

  FIG. 7 is an explanatory view schematically showing a state where the fuel cell 100 is inclined such that the front end of the fuel cell 100 is vertically downward. The inclination attitude of the fuel cell 100 shown in the figure may occur in a process where a vehicle equipped with the fuel cell 100 is traveling on an inclined road or parked on an inclined road surface, and when the fuel cell 100 becomes such an inclination attitude 30 also inclines. Even in such an inclined posture, the fuel cell 100 configured by the fuel cell 110 of the present embodiment holds the water W in the gap recess 23 in each fuel cell 110 and the resin surrounding the gap recess 23. Since the retention of the water retention state of the water W in the gap recess 23 by making the sheet 20 and the separators 40a and 40b hydrophilic, as shown in FIG. 7, even if the fuel cell 100 is inclined, the front end of the fuel cell It is possible to suppress the occurrence of a situation where water W flows down along the slope and is accumulated on the side of the As a result, according to the fuel cell 110 of the present embodiment, even when the fuel cell 100 is inclined as shown in FIG. 7, the gas supply / discharge through the gas manifold 30 in the fuel cell 110 on the lower side of the inclination is Therefore, the power generation performance of the fuel cell 110 can be maintained.

  The fuel cell 110 according to the present embodiment includes the gas supply / discharge passage 50 at a position lower than the bottom wall surface 30bt of the separator-side manifold hole 30b in the cell height direction (y-axis direction) as shown in FIG. The water W held in the gap recess 23 can be reliably guided to the power generation body 10 through the gas supply / discharge passage 50.

  As shown in FIGS. 5 and 6, the fuel cell 110 of the present embodiment has a gap recess 23 also on the side wall 30 as of the gas manifold 30. Therefore, even in the gap recess 23 in the side wall 30as, the water W can be retained by the hydrophilicity of the resin sheet 20 and the separators 40a and 40b and the capillary force acting between narrow cells. Therefore, also from this point, according to the fuel cell 110 of the present embodiment, the gas supply via the gas manifold 30 in the fuel cell 110 on the lower side of the inclination when the fuel cell 100 is inclined as described above Since the exhaust is not inhibited, it can contribute to the maintenance of the power generation performance of the fuel cell 110. The same applies to the ceiling wall surface of the sheet side manifold hole 30a facing the bottom wall surface 30at.

  Although the fuel cell 110 of the present embodiment guides the water W held in the gap recess 23 to the membrane electrode assembly of the power generation body 10 through the gas supply / discharge passage 50, the amount is held in the gap recess 23 Limited to a small amount of water. Therefore, according to the fuel cell 110 of the present embodiment, excessive humidification of the power generation body 10 by the water W retained in the gap recess 23 is not excessive, and the power generation performance of the fuel cell 110 is inadvertently lowered. I will not come.

  FIG. 8 is an explanatory view showing the gas manifold 30 in a sectional view equivalent to FIG. 4 in a state where a plurality of fuel cells 110A of the first modification are stacked. In the fuel cell 110A of the first modification, instead of using a resin sheet 20 having a single thickness, a resin sheet 20 having irregularities in thickness is used to resin the space recess 23 in a state where the fuel cell 110A is stacked. It is characterized in that it is formed of the sheet 20 and the separators 40a and 40b. Also according to the fuel cell 110A of the first modification, the water retention of the water W in the gap recess 23 in each fuel cell 110A, the resin sheet 20 surrounding the gap recess 23, and the separators 40a and 40b are hydrophilic. By the retention of the water retention state of the water W in the gap recess 23 due to the above, it is possible to achieve the effects described above.

  FIG. 9 is an explanatory view showing the gas manifold 30 in a sectional view equivalent to FIG. 4 in a state where a plurality of fuel cells 110B of the second modification are stacked. The fuel cell unit 110B of the second modification is characterized in that the gap recess 23 is formed in a state where the fuel cell unit 110A is stacked. Also in the fuel cell 110B of the second modification, the water retention of the water W in the gap recess 23 in each fuel cell 110B, and the resin sheet 20 surrounding the gap recess 23 and the separators 40a and 40b are made hydrophilic. By the retention of the water retention state of the water W in the gap recess 23 due to the above, it is possible to achieve the effects described above.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be implemented with various configurations without departing from the scope of the invention. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in the respective forms described in the section of the summary of the invention are for solving some or all of the problems described above, or In order to achieve part or all of the above-described effects, replacements or combinations can be made as appropriate. Also, if the technical features are not described as essential in the present specification, they can be deleted as appropriate.

  In the embodiment described above, although the resin sheet 20 and the separators 40a and 40b are made hydrophilic in the surrounding area of the gap recess 23, the present invention is not limited to this. For example, hydrophilicity may be imparted only to the side of the resin sheet 20 in the encircling region of the gap recess 23, or hydrophilicity may be imparted to only the side of the separators 40a and 40b.

  In the embodiment described above, the gap recess 23 is formed on the bottom of the gas manifold 30 on the air-out side, and the resin sheet 20 and the separators 40a and 40b have hydrophilicity in the surrounding region. Not exclusively. For example, in addition to the gas manifold 30 on the air-in side, either one of the out-side or in-side gas manifolds 30 for hydrogen gas, or both the gas manifold 30 on the out-side and in-side of air, A gap recess 23 is formed in either or both of the out-side and in-side gas manifolds 30 for hydrogen gas, and the resin sheet 20 and the separators 40a and 40b are made hydrophilic in the surrounding area. You may give it. In addition, the gap recess 23 is formed in all the gas manifolds 30 on the outside and in the side for air and hydrogen gas, and the resin sheet 20 and the separators 40a and 40b are rendered hydrophilic in the surrounding area thereof. It is also good.

  In the embodiment described above, the gap recess 23 is formed in the entire area of the bottom of the gas manifold 30, but at least a partial area of the bottom of the gas manifold 30, for example, the central area of the bottom of the gas manifold 30, The gap recess 23 may be formed in both end regions of the bottom side. As described above, when the gap recess 23 is formed in a partial region of the bottom side, the formation region of the gap recess 23 can be 70 to 90% of the entire bottom surface of the gas manifold 30.

  In the embodiment described above, the gap recess 23 is formed in the side wall and the ceiling wall of the gas manifold 30, but the gap recess 23 between the side wall and the ceiling wall may be omitted.

  In the embodiment described above, all the fuel cells 110 stacked between the end plate 170F and the end plate 170E are the cells having the gap recess 23, but the invention is not limited thereto. For example, the fuel cell 110 excluding the predetermined range on the end plate side (5 to 10% of the cell stacking range) is a fuel cell having the gap recess 23 and the fuel cell 110 in the predetermined range on the end plate side The fuel cell may not have the gap recess 23.

DESCRIPTION OF SYMBOLS 10 ... Power generation body 20 ... Resin sheet 21 ... Opening part 23 ... Gap recess 30 ... Gas manifold 30a ... Sheet side manifold hole 30as ... Side wall 30at ... Bottom wall 30b ... Separator side manifold hole 30bs ... Side wall 30 bt ... Bottom wall surface 31 ... cooling manifold hole 40a ... separator 40b ... separator 41 ... channel 42 ... distribution channel 43 ... merging channel 50 ... gas supply / discharge channel 51 ... gas introduction part 60 ... gasket 100 ... fuel cell 110, 110A, 110B ... Fuel cell 116 ... Supply manifold 117 ... Discharge manifold 118 ... Supply manifold 119 ... Discharge manifold 160 E ... Terminal plate 160 F ... Terminal plate 165 E ... Insulating plate 165 F ... Insulating plate 170 F ... End plate 170 E ... En Plateau D ... difference W ... water

Claims (1)

A fuel cell stack comprising a plurality of fuel cells stacked with a membrane electrode assembly surrounded by a frame-like resin sheet, and the resin sheet being sandwiched between the cathode side and anode side separators in the outer edge region of the membrane electrode assembly. There,
The separator manifold holes provided in the outer edge area of the both separators and the sheet manifold holes provided in the outer edge area of the resin sheet form a gas manifold by stacking the fuel cells.
In at least a partial area of the bottom side of the gas manifold, the front end of the resin sheet is located more inward of the gas manifold than the front ends of the two separators,
The two separators form a space recess in at least one of the sheet surfaces of the resin sheet on the side of the bottom of the gas manifold,
The resin sheet has a gas supply and discharge path for gas supply and discharge from the gap recess to the membrane electrode assembly,
At least one of the both separators surrounding the gap recess and the resin sheet is hydrophilic in the surrounding area of the gap recess,
Fuel cell stack.

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