JP2021044063A - Cell stack of fuel cell - Google Patents

Abstract

To provide a cell stack of fuel cell capable of suppressing fracture of the juncture of a resin plate and the peripheral part of a membrane electrode gas diffusion layer juncture.SOLUTION: A Cell stack of fuel cell is equipped with a fuel battery cell 1 having a sheet-like membrane electrode gas diffusion layer juncture 2, a resin plate 3 bonded to the peripheral part of the membrane electrode gas diffusion layer juncture 2, and a pair of separators 4, 5 sandwiching the membrane electrode gas diffusion layer juncture 2 and the resin plate 3 in the thickness direction. In the cell stack, multiple fuel battery cells 1 are laminated in the thickness direction. The portions overlapping in the thickness direction at the peripheral part of the resin plate 3 and the membrane electrode gas diffusion layer juncture 2 are junctures 17 to be bonded each other. The separators 4, 5 have adhesion parts 4a, 5a adhering to the junctures 17, respectively. At the portions corresponding to the adhesion parts 4a, 5a, between the separators 4, 5 of adjoining fuel battery cells, a packing 25 for pressing the adhesion parts 4a, 5a to the side of the junctures 17 is provided.SELECTED DRAWING: Figure 3

Description

The present invention relates to a cell stack of a fuel cell.

The cell stack of the fuel cell is formed by stacking the fuel cell cells shown in Patent Document 1 in the thickness direction thereof. As shown in FIG. 4, such a fuel cell 51 is joined to a sheet-shaped membrane electrode gas diffusion layer assembly (MEGA) 52 and a peripheral edge of the membrane electrode gas diffusion layer assembly 52. The resin plate 53 is provided. Further, the fuel cell 51 also includes a pair of separators 54 and 55 that sandwich the membrane electrode gas diffusion layer joint 52 and the resin plate 53 in the thickness direction.

The membrane electrode gas diffusion layer junction 52 includes, for example, an electrolyte layer 56 formed of a solid polymer membrane, a cathode electrode layer 57 bonded to one side of the electrolyte layer 56 in the thickness direction, and a thickness of the electrolyte layer 56. It includes an anode electrode layer 58 bonded to the other side in the longitudinal direction. Further, the surface of the cathode electrode layer 57 opposite to the electrolyte layer 56 is covered with the gas diffusion layer 59, and the surface of the anode electrode layer 58 opposite to the electrolyte layer 56 is covered with the gas diffusion layer 60.

Further, at the peripheral portion of the membrane electrode gas diffusion layer joint 52, the gas diffusion layer 59 and the cathode electrode layer 57 are omitted, and the electrolyte layer 56 is exposed. The resin plate 53 is bonded to the peripheral portion of the membrane electrode gas diffusion layer joint 52 and the exposed portion of the electrolyte layer 56 so as to overlap in the thickness direction with an adhesive or the like. Therefore, in the fuel cell 51, the portion of the resin plate 53 and the peripheral edge of the membrane electrode gas diffusion layer joint 52 that overlap in the thickness direction is a joint 67 that is joined to each other.

The pair of separators 54 and 55 are bonded to the resin plate 53 so as to be sandwiched in the thickness direction, and the membrane electrode gas diffusion layer bonded body 52 is sandwiched in the thickness direction. The resin plate 53 is for insulating one separator 54 and the other separator 55 in the pair of conductive separators 54 and 55. Further, the resin plate 53 is for partitioning a portion between one separator 54 and the membrane electrode gas diffusion layer junction 52 and a portion between the other separator 55 and the membrane electrode gas diffusion layer junction 52. It is also a thing.

A plurality of concave portions 61 and a plurality of convex portions 62 are formed on each of the separators 54 so as to be parallel and staggered. The convex portion 62 of one of the separators 54 is in contact with the gas diffusion layer 59 on the cathode electrode layer 57 side of the membrane electrode gas diffusion layer joint 52. In one separator 54, a flow path 63 for flowing an oxidizing gas such as air is formed inside the concave portion 61 located between the convex portions 62. The oxidizing gas flowing in the flow path 63 is efficiently guided to the cathode electrode layer 57 by the gas diffusion layer 59.

The other separator 55 is formed with a plurality of concave portions 64 and a plurality of convex portions 65, respectively, so as to be parallel and staggered. The convex portion 65 of the other separator 55 is in contact with the gas diffusion layer 60 on the anode electrode layer 58 side of the membrane electrode gas diffusion layer joint 52. In the other separator 55, a flow path 66 for flowing a fuel gas such as hydrogen is formed inside the concave portion 64 located between the convex portions 65. The fuel gas flowing in the flow path 66 is efficiently guided to the anode electrode layer 58 by the gas diffusion layer 60.

Then, in the film electrode gas diffusion layer junction 52, when fuel gas is supplied to the anode electrode layer 58 and oxidation gas is supplied to the cathode electrode layer 57 of the membrane electrode gas diffusion layer junction 52, these fuel gases and Power is generated based on the reaction of the oxide gas at the film electrode gas diffusion layer junction 52. While such power generation causes thermal expansion of the fuel cell 51, thermal contraction of the fuel cell 51 occurs due to the stoppage of the power generation.

JP-A-2017-224588

By the way, in the fuel cell 51, there is a difference in the coefficient of thermal expansion and the coefficient of thermal shrinkage between the resin plate 53 and the pair of separators 54 and 55 due to the difference in the materials of the two. Due to such a difference in the coefficient of thermal expansion and the coefficient of thermal contraction, a force acts on the resin plate 53 sandwiched between the pair of separators 54 and 55 in a direction parallel to the separators 54 and 55, that is, in the left-right direction of FIG. .. Then, the action of the above force causes the resin plate 53 to bend in the direction away from the electrolyte layer 56 of the membrane electrode gas diffusion layer joint 52, that is, in the direction of the arrow in FIG. As the resin plate 53 bends, the joint portion (joint portion 67) between the resin plate 53 and the electrolyte layer 56 of the membrane electrode gas diffusion layer joint 52 may break.

An object of the present invention is to provide a cell stack of a fuel cell capable of suppressing breakage of a joint portion between a resin plate and a peripheral portion of a membrane electrode gas diffusion layer joint body.

Hereinafter, means for solving the above problems and their actions and effects will be described.
The cell stack of the fuel cell that solves the above problems includes a sheet-shaped membrane electrode gas diffusion layer junction, a resin plate bonded to the peripheral edge of the membrane electrode gas diffusion layer junction, and a membrane electrode gas diffusion layer junction. It includes a fuel cell having a pair of separators that sandwich the body and the resin plate in the thickness direction. Then, in the fuel cell cell stack, a plurality of fuel cell cells are stacked in the thickness direction. The portion of the resin plate of the fuel cell and the peripheral edge of the membrane electrode gas diffusion layer joint that overlaps in the thickness direction is a joint that is joined to each other. Each of the pair of separators in the fuel cell has a contact portion that is in close contact with the joint portion. Further, an elastic body is provided between the separators of the adjacent fuel cell cells and corresponding to the close contact portion to press the close contact portion toward the joint portion side.

According to the above configuration, in a plurality of fuel cell cells stacked in the thickness direction, an elastic body provided between the separators of adjacent fuel cell cells is bonded to the resin plate and the membrane electrode gas diffusion layer. The joint portion, which is a portion that overlaps with the peripheral edge portion of the body in the thickness direction, is pressed through the close contact portion of the separator that is in close contact with the joint portion. During power generation or when the power generation is stopped, a force in a direction parallel to the separator acts on the resin plate due to the difference in the coefficient of thermal expansion and the coefficient of thermal contraction between the resin plate and the pair of separators. Then, although the resin plate tries to bend in the direction away from the membrane electrode gas diffusion layer joint by the action of the force, the displacement of the resin plate in the direction away from the membrane electrode gas diffusion layer joint due to such bending is the above-mentioned adhesion. It is suppressed by the pressing of the elastic body that sandwiches the joint portion through the portion. Therefore, it is possible to suppress the occurrence of breakage at the joint portion between the resin plate and the peripheral portion of the membrane electrode gas diffusion layer joint due to the thermal expansion and contraction of the resin plate and the pair of separators.

Front view showing a fuel cell. An exploded perspective view showing a fuel cell. FIG. 5 is a cross-sectional view showing a state in which a fuel cell (cell stack) is viewed from the direction of arrows AA in FIG. The cross-sectional view which shows the conventional example in the cell stack of a fuel cell.

Hereinafter, an embodiment of the cell stack of the fuel cell will be described with reference to FIGS. 1 to 3.
1 and 2 show a state in which the fuel cell 1 is viewed from the front and a state in which the fuel cell 1 is disassembled, respectively. As can be seen from these figures, the fuel cell 1 has a square sheet-like membrane electrode gas diffusion layer junction 2 and a square frame shape joined to the peripheral edge of the membrane electrode gas diffusion layer junction 2. It is provided with a resin plate 3 forming the above, and a pair of plate-shaped separators 4 and 5 having conductivity for sandwiching the membrane electrode gas diffusion layer joint 2 and the resin plate 3 in the thickness direction. The cell stack of the fuel cell is formed by stacking a plurality of fuel cell cells 1 in the thickness direction thereof.

The resin plate 3 and the pair of separators 4 and 5 of the fuel cell 1 are formed with through holes 6 for allowing fuel gas such as hydrogen to flow into the cell stack and through holes 7 for allowing the fuel gas to flow out of the cell stack. ing. The resin plate 3 and the pair of separators 4 and 5 are formed with through holes 8 for allowing an oxidizing gas such as air to flow into the cell stack, and through holes 9 for allowing the oxidizing gas to flow out of the cell stack. The resin plate 3 and the pair of separators 4 and 5 are formed with through holes 10 for allowing a cooling fluid such as cooling water to flow into the cell stack, and through holes 11 for allowing the cooling fluid to flow out of the cell stack.

As shown in FIG. 3, in the film electrode gas diffusion layer junction 2, the cathode electrode layer 13 is bonded to one side in the thickness direction of the electrolyte layer 12 formed by the solid polymer membrane, and the cathode electrode layer A gas diffusion layer 14 is bonded to the surface of No. 13 opposite to the electrolyte layer 12. Further, the anode electrode layer 15 is bonded to the other side of the electrolyte layer 56 in the thickness direction, and the gas diffusion layer 16 is bonded to the surface of the anode electrode layer 15 opposite to the electrolyte layer 12.

At the peripheral edge of the membrane electrode gas diffusion layer junction 2, the gas diffusion layer 14 and the cathode electrode layer 13 are omitted to expose the electrolyte layer 12, and the resin plate 3 is thicker than the exposed portion of the electrolyte layer 12. It is joined so that it overlaps in the direction. The portion of the resin plate 3 and the peripheral portion of the membrane electrode gas diffusion layer joint 2 that overlap each other in the thickness direction is a joint portion 17 that is joined to each other by an adhesive or the like. Further, the pair of separators 4 and 5 are bonded to the resin plate 3 so as to be sandwiched in the thickness direction thereof, and the membrane electrode gas diffusion layer bonded body 2 is sandwiched in the thickness direction.

Further, the separator 4 has a close contact portion 4a that is in close contact with the portion corresponding to the joint portion 17 of the resin plate 3, and the separator 5 is attached to the joint portion 17 at the peripheral portion of the membrane electrode gas diffusion layer joint body 2. It has a close contact portion 5a that is in close contact with the corresponding portion. The separator 4 and the separator 5 are insulated from each other by the resin plate 3. Further, the portion between the separator 4 and the membrane electrode gas diffusion layer junction 2 and the portion between the separator 5 and the membrane electrode gas diffusion layer junction 2 are partitioned by the resin plate 3.

In the cell stack, a packing 25 formed of an elastic material such as rubber is provided between the separators 4 and 5 of the adjacent fuel cell 1 and corresponding to the close contact portions 4a and 5a. ing. The packing 25 is pressed against the close contact portions 4a and 5a of the separators 4 and 5 to ensure the sealing property between the close contact portions 4a and 5a. The packing 25 also serves as an elastic body that presses the contact portions 4a and 5a of the separators 4 and 5 toward the joint portion 17.

A plurality of concave portions 18 and a plurality of convex portions 19 are formed on the separator 4 so as to be parallel and staggered, and the convex portions 19 are in contact with the gas diffusion layer 14 on the cathode electrode layer 13 side. Further, in the separator 4, a flow path 20 is formed inside the concave portion 18 located between the convex portions 19 to allow the oxidizing gas flowing into the cell stack to flow through the through hole 8 (FIG. 1). .. A part of the oxidizing gas flowing in the flow path 20 is efficiently guided to the cathode electrode layer 13 by the gas diffusion layer 14. Further, the oxidizing gas that has passed through the flow path 20 flows out from the cell stack through the through hole 9 (FIG. 1).

As shown in FIG. 3, a plurality of concave portions 21 and a plurality of convex portions 22 are formed in the separator 5 so as to be parallel and staggered, and the convex portions 22 are a gas diffusion layer on the anode electrode layer 15 side. It is in contact with 16. Further, in the separator 5, a flow path 23 for flowing the fuel gas flowing into the cell stack through the through hole 6 (FIG. 1) is formed inside the concave portion 21 located between the convex portions 22. ing. A part of the fuel gas flowing in the flow path 23 is efficiently guided to the anode electrode layer 15 by the gas diffusion layer 16. Further, the fuel gas that has passed through the flow path 23 flows out from the cell stack through the through hole 7 (FIG. 1).

In the film electrode gas diffusion layer junction 2 shown in FIG. 3, when fuel gas is supplied to the anode electrode layer 15 and oxidation gas is supplied to the cathode electrode layer 13 of the membrane electrode gas diffusion layer junction 2, those fuels are supplied. Power is generated based on the reaction of the gas and the oxide gas in the membrane electrode gas diffusion layer junction 2.

In order to cool the fuel cell 1 that generates heat due to such power generation, the cooling fluid that has flowed into the cell stack is allowed to flow between the separators 4 and 5 of the adjacent fuel cell 1 through the through holes 10 (FIG. 1). A flow path 24 for the purpose is formed. The cooling fluid that has passed through the flow path 24 flows out from the cell stack through the through hole 11 (FIG. 1). The leakage of the cooling fluid flowing through the flow path 24 from between the separators 4 and 5 is suppressed by the packing 25 shown in FIG. Then, in the fuel cell 1, thermal expansion occurs due to the heat generation during power generation, while thermal contraction occurs due to cooling by the cooling fluid when the power generation is stopped.

Next, the packing 25 will be described in detail.
The packing 25 is provided so as to have a plurality of stages in the stacking direction of the fuel cell 1 in FIG. 3 (vertical direction in FIG. 3). Note that FIG. 3 shows only three stages of the plurality of fuel cell 1 stacked in the thickness direction in the cell stack. The uppermost packing 25 in FIG. 3 represents a state when the packing 25 is not sandwiched by the fuel cell 1 and is not elastically deformed. Further, the packing 25 other than the uppermost packing 25 in FIG. 3 represents a state in which the packing 25 is sandwiched by the fuel cell 1 and is elastically deformed by the packing 25.

As can be seen from FIG. 3, the packing 25 is provided between the separators 4 and 5 of the adjacent fuel cell 1s, specifically, the portions corresponding to the close contact portions 4a and 5a of the separators 4 and 5. The packing 25 is formed so as to form an annular shape corresponding to the square frame-shaped resin plate 3. The packing 25 is provided so that the through holes 10 and 11 are located inside the packing 25 formed in an annular shape, for example, as shown by the alternate long and short dash line in FIG.

The packing 25 has a base portion 25a in which a portion closer to the resin plate 3 is bonded to the close contact portion 4a of the separator 4 with an adhesive or the like, while a portion protruding from the base portion 25a in a direction away from the resin plate 3 is a top portion. It is said to be 25b. Here, assuming that the distance between the ends 3a and 2a of the resin plate 3 and the peripheral edge of the membrane electrode gas diffusion layer joint 2 in the joint 17 is X, the direction connecting the ends 3a and 2a (FIG. 3). The width of the packing 25 in the left-right direction of the packing 25, more specifically, the width of the base portion 25a of the packing 25 is made larger than the distance X.

Further, in the top 25b of the packing 25, the width in the protruding direction (upward direction in FIG. 3) is reduced toward the tip, that is, the width in the direction connecting the ends 3a and 2a is reduced. Further, the tip of the top portion 25b in the protruding direction is located corresponding to the center of the base portion 25a in the direction connecting the ends 3a and 2a.

Next, the operation of the cell stack of the fuel cell in the present embodiment will be described.
In the plurality of fuel cell 1 stacked in the thickness direction, the packing 25 provided between the separators 4 and 5 of the adjacent fuel cell 1 is joined to the resin plate 3 and the membrane electrode gas diffusion layer. The joint portion 17, which is a portion that overlaps the peripheral edge portion of the body 2 in the thickness direction, is pressed via the close contact portions 4a, 5a of the separators 4 and 5 that are in close contact with the joint portion 17.

Here, in the fuel cell 1, when power generation is performed or when the power generation is stopped, the heat expansion rate and the heat shrinkage rate of the resin plate 3 and the pair of separators 4 and 5 are different from each other. A force in the parallel direction (left-right direction in FIG. 3) acts on the resin plate 3. Then, due to the action of the force, the resin plate 3 tends to bend in the direction away from the membrane electrode gas diffusion layer joint 2, that is, in the direction of the arrow Y in FIG.

However, the displacement of the resin plate 3 in the direction away from the film electrode gas diffusion layer joint 2 due to such curvature is suppressed by pressing the packing 25 that sandwiches the joint 17 via the close contact portions 4a and 5a of the separators 4 and 5. Will be done. Therefore, it is possible to prevent the resin plate 3 and the pair of separators 4 and 5 from being broken at the joint portion 17 between the resin plate 3 and the peripheral portion of the membrane electrode gas diffusion layer joint 2 due to thermal expansion and contraction. Will be done.

According to the present embodiment described in detail above, the following effects can be obtained.
(1) A joint portion 17 between the resin plate 3 and the peripheral portion of the membrane electrode gas diffusion layer joint body 2 due to thermal expansion and thermal contraction of the resin plate 3 and the pair of separators 4 and 5 during power generation and stoppage thereof. It is possible to suppress the occurrence of breakage at.

(2) The width of the packing 25 in the direction connecting the ends 3a and 2a between the resin plate 3 and the peripheral edge of the membrane electrode gas diffusion layer joint 2, that is, the width of the base 25a is larger than the distance X. .. Therefore, in a state where the entire width direction of the packing 25 is positioned corresponding to the joint portion 17 between the resin plate 3 and the peripheral edge portion of the membrane electrode gas diffusion layer joint body 2, the packing 25 attaches the joint portion 17 to the joint portion 17. The separators 4 and 5 are pressed through the close contact portions 4a and 5a. As a result, the pressing by the packing 25 can be stably performed.

(3) At the top 25b of the packing 25, the width in the direction connecting the ends 3a and 2a between the resin plate 3 and the peripheral edge of the membrane electrode gas diffusion layer joint 2 increases toward the tip in the protruding direction. It has been made smaller. Therefore, when the top portion 25b of the packing 25 presses the joint portion 17 via the close contact portion 5a of the separator 5, the pressing force per unit area due to the pressing can be increased. Therefore, with the thermal expansion and contraction of the resin plate 3 and the pair of separators 4 and 5, breakage occurs at the joint portion 17 between the resin plate 3 and the peripheral portion of the membrane electrode gas diffusion layer joint body 2. It can be suppressed more effectively by the above pressing.

(4) The tip of the top 25b of the packing 25 in the protruding direction corresponds to the center of the base 25a in the direction connecting the ends 3a and 2a between the resin plate 3 and the peripheral edge of the membrane electrode gas diffusion layer joint 2. positioned. Here, when the fuel cell 1 is laminated in the thickness direction, the relative position of the adjacent fuel cell 1 may deviate from an appropriate position with respect to the direction connecting the ends 3a and 2a at the joint portion 17. There is sex. When such a displacement occurs, the relative positions of the top 25b of the packing 25 and the contact portion 5a in which the top 25b is in contact with the joint portion 17 corresponding to the contact portion 5a also shift in the above direction. However, since the tip of the packing 25 in the protruding direction of the top 25b is located corresponding to the center of the base 25a in the above direction, the top 25b is joined in the above direction even if the above-mentioned relative position deviation occurs. It becomes difficult to come off from the position corresponding to the portion 17.

(5) Adjacent film A flow path 24 for flowing a cooling fluid is formed between the separators 4 and 5 of the electrode gas diffusion layer joint 2, and the cooling fluid flowing through the flow path 24 is an adjacent film. Leakage from between the separators 4 and 5 of the electrode gas diffusion layer joint 2 can be suppressed by the packing 25.

The above embodiment can be changed as follows, for example. The above embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
In the packing 25, the tip of the top 25b in the protruding direction necessarily corresponds to the center of the base 25a in the direction connecting the ends 3a and 2a between the resin plate 3 and the peripheral edge of the membrane electrode gas diffusion layer joint 2. It doesn't have to be located.

The packing 25 is formed in a mountain-shaped shape having a base portion 25a and a top portion 25b, but it is not always necessary to have such a shape, and other shapes can be adopted.
-In the packing 25, the width in the direction connecting the end portions 3a and 2a of the resin plate 3 and the peripheral edge portion of the membrane electrode gas diffusion layer joint 2 does not necessarily have to be larger than the distance X.

-The packing 25, which plays a role as an elastic body, secures the sealing property between the contact portions 4a and 5a by being pressed against the contact portions 4a and 5a of the separators 4 and 5. Another elastic body may be adopted instead of the packing 25 having such a function. That is, when the cell stack has a structure in which no fluid flows between the separators 4 and 5 of the adjacent fuel cell 1, the elastic body does not have the function of ensuring the sealing property instead of the packing 25. It is also possible to provide.

-Although the packing 25 is provided as an elastic body, an elastic body having no sealing function may be used.

1 ... Fuel cell, 2 ... Membrane electrode gas diffusion layer junction, 2a ... End, 3 ... Resin plate, 3a ... End, 4 ... Separator, 4a ... Adhesion, 5 ... Separator, 5a ... Adhesion, 6 ... through hole, 7 ... through hole, 8 ... through hole, 9 ... through hole, 10 ... through hole, 11 ... through hole, 12 ... electrolyte layer, 13 ... cathode electrode layer, 14 ... gas diffusion layer, 15 ... anode electrode Layer, 16 ... gas diffusion layer, 17 ... joint, 18 ... concave, 19 ... convex, 20 ... flow path, 21 ... concave, 22 ... convex, 23 ... flow path, 24 ... flow path, 25 ... packing, 25a ... base, 25b ... top.

Claims (5)

A sheet-shaped membrane electrode gas diffusion layer junction, a resin plate bonded to the peripheral edge of the membrane electrode gas diffusion layer junction, the membrane electrode gas diffusion layer junction, and the resin plate are sandwiched in the thickness direction. In a fuel cell cell stack comprising a fuel cell having a pair of separators and in which a plurality of the fuel cell cells are stacked in the thickness direction.
The portion of the fuel cell cell that overlaps in the thickness direction between the resin plate and the peripheral edge of the membrane electrode gas diffusion layer joint is a joint that is joined to each other.
Each of the pair of separators in the fuel cell has a contact portion that is in close contact with the joint portion.
A fuel cell characterized in that an elastic body for pressing the close contact portion toward the joint portion is provided in a portion between adjacent separators of the fuel cell cells and corresponding to the close contact portion. Cell stack. When the distance between the ends of the resin plate and the peripheral edge of the membrane electrode gas diffusion layer joint is X at the joint, the width of the elastic body in the direction connecting the ends is greater than the distance X. The cell stack of the fuel cell according to claim 1, which is also enlarged. The elastic body has a portion closer to the resin plate as the base portion, and a portion protruding from the base portion in a direction away from the resin plate as a top portion.
The cell stack of the fuel cell according to claim 2, wherein in the elastic body, the width is made larger than the distance X at the base portion, and the width is made smaller toward the tip in the protruding direction at the top portion. .. The base portion is joined to the close contact portion, and the base portion is joined to the close contact portion.
The third aspect of the present invention, wherein the tip of the top in the protruding direction is located corresponding to the center of the base in the direction connecting the ends of the resin plate and the peripheral edge of the membrane electrode gas diffusion layer joint. Fuel cell cell stack. A fluid can flow between the separators of the adjacent fuel cell cells.
The fuel cell according to any one of claims 1 to 4, wherein the elastic body is a packing that secures a sealing property between the elastic body and the contact portion by being pressed against the close contact portion of the separator. Cell stack.