Fuel battery cell

Abstract

To provide a fuel battery cell with which it is possible to adjust the thickness of an adhesive layer and the amount of collapse of a membrane electrode assembly and a gas diffusion layer to appropriate values when a separator pressurizes the membrane electrode assembly, the gas diffusion layer and an insulating member while sandwiching these from both sides in the thickness direction.SOLUTION: A fuel battery cell 11 comprises a membrane electrode assembly 12, a gas diffusion layer 13, an insulating sheet 14, a separator 15, and an adhesive layer 16. The insulating sheet 14 is located on both sides of an outer edge of the membrane electrode assembly 12 in the thickness direction. The gas diffusion layer 13 is located on both sides inward of an outer edge of the membrane electrode assembly 12 in the thickness direction. The separator 15 pressurizes the membrane electrode assembly 12, the gas diffusion layer 13, and the insulating sheet 14 by sandwiching these from both sides in the thickness direction. The adhesive layer 16 is formed between the separator 15 and the insulating sheet 14 and between the insulating sheet 14 and the outer edge of the membrane electrode assembly 12 by an adhesive 23 containing a number of spacers 22 that are mixed in.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to fuel cells. [Background technology]

[0002] A cell stack of a fuel cell mounted on a vehicle or the like is formed by stacking fuel cell units, as shown in Patent Document 1, in the thickness direction, for example. The fuel cell includes a membrane electrode assembly (MEA), a gas diffusion layer (GDL), an insulating member, and a separator. A frame-shaped insulating member is bonded to the outer edge of the membrane electrode assembly. The gas diffusion layers are disposed on both sides in the thickness direction on the inner side of the outer edge of the membrane electrode assembly. The separator is made of a conductive material. The separator presses the membrane electrode assembly, the gas diffusion layer, and the insulating sheet by sandwiching them from both sides in the thickness direction. The insulating member is bonded to the separator by an adhesive layer.

[0003] When a plurality of fuel cells are stacked to form a cell stack, the separator presses the membrane electrode assembly, the gas diffusion layer, and the insulating member from both sides in the thickness direction. A fuel gas such as hydrogen is supplied to one side in the thickness direction of the membrane electrode assembly and the gas diffusion layer in the fuel cell, and an oxidizing gas such as air is supplied to the other side in the thickness direction. As a result, the fuel cell generates electricity based on a reaction between the fuel gas and the oxidizing gas.

[0004] In the above fuel cell stack, the membrane electrode assemblies and gas diffusion layers of the stacked fuel cell cells are pressed in the thickness direction by the separator as described above, thereby reducing the electrical resistance (contact resistance) in the fuel cell cells. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-98164 A Summary of the Invention [Problem to be solved by the invention]

[0006] When the separator presses the membrane electrode assembly, the gas diffusion layer, and the insulating member from both sides in the thickness direction, the thickness of the adhesive layer of the insulating member becomes thinner due to the pressure. The membrane electrode assembly and the gas diffusion layer are crushed in the thickness direction by the amount of the thinner adhesive layer. The amount of crushing of the membrane electrode assembly and the gas diffusion layer at this time affects the electrical resistance of the fuel cell. Furthermore, the thickness of the adhesive layer at this time affects the adhesion of the adhesive member to the separator by the adhesive layer.

[0007] However, in the above fuel cell, it is not possible to adjust the thickness of the adhesive layer and the amount of crushing of the membrane electrode assembly and the gas diffusion layer when the separator sandwiches and pressurizes the membrane electrode assembly, the gas diffusion layer, and the insulating member from both sides in the thickness direction. Therefore, it is not possible to adjust the thickness of the adhesive layer when the above pressure is applied to a value appropriate for bonding the adhesive member to the separator by the adhesive layer. In addition, it is not possible to adjust the amount of crushing of the membrane electrode assembly and the gas diffusion layer to a value appropriate for reducing the electrical resistance in the fuel cell. [Means for solving the problem]

[0008] The means for solving the above problems and their effects will be described below. A fuel cell that solves the above problems includes a membrane electrode assembly, a gas diffusion layer, an insulating sheet, a separator, and an adhesive layer. The insulating sheets are disposed on both sides in the thickness direction at the outer edge of the membrane electrode assembly. The gas diffusion layers are disposed on both sides in the thickness direction on the inner side of the outer edge of the membrane electrode assembly. The separator presses the membrane electrode assembly, the gas diffusion layer, and the insulating sheet by sandwiching them from both sides in the thickness direction. The adhesive layer is formed between the separator and the insulating sheet and between the insulating sheet and the outer edge of the membrane electrode assembly by an adhesive having a large number of spacers mixed in.

[0009] According to the above configuration, when the separator presses the membrane electrode assembly, the gas diffusion layer, and the insulating sheet by sandwiching them from both sides in the thickness direction, the thickness of the adhesive layer becomes thinner with the pressurization. However, since a large number of spacers are mixed into the adhesive forming the adhesive layer, the thickness of the adhesive layer when the thickness of the adhesive layer becomes thinner as described above is adjusted to a thickness corresponding to the size of the spacers. As a result, the crushing amount of the membrane electrode assembly and the gas diffusion layer at this time is also adjusted to a value corresponding to the size of the spacers. Therefore, by appropriately changing the size of the spacers mixed into the adhesive, the thickness of the adhesive layer and the crushing amount of the membrane electrode assembly and the gas diffusion layer can be appropriately adjusted as follows. That is, the thickness of the adhesive layer can be adjusted to a value appropriate for adhesion by the adhesive layer, and the crushing amount of the membrane electrode assembly and the gas diffusion layer can be adjusted to a value appropriate for reducing the electrical resistance in the fuel cell. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a cross-sectional view showing a fuel cell. [Diagram 2] 2 is an enlarged cross-sectional view showing the outer edge of the fuel cell in FIG. 1. [Diagram 3] 3 is a cross-sectional view showing another example of the fuel cell of FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, one embodiment of a fuel cell will be described with reference to FIGS. As shown in Fig. 1, a fuel cell stack is formed by stacking a plurality of fuel cell units 11 in the thickness direction. The fuel cell unit 11 includes a membrane electrode assembly 12, a gas diffusion layer 13, an insulating sheet 14, a separator 15, and an adhesive layer 16. The membrane electrode assembly 12 is formed in a sheet shape. The membrane electrode assembly 12 includes an electrolyte membrane 17, an anode electrode layer 18, and a cathode electrode layer 19.

[0012] The anode electrode layer 18 is bonded to one of the two sides in the thickness direction of the electrolyte membrane 17, i.e., the lower side in FIG. 1. A gas diffusion layer 13 is bonded to the side of the anode electrode layer 18 opposite to the side bonded to the electrolyte membrane 17, i.e., the lower side in FIG. 1. The cathode electrode layer 19 is bonded to the other side of the electrolyte membrane 17, i.e., the upper side in FIG. 1. A gas diffusion layer 13 is bonded to the side of the cathode electrode layer 19 opposite to the side bonded to the electrolyte membrane 17, i.e., the upper side in FIG. 1. In this way, the gas diffusion layers 13 are arranged on both sides in the thickness direction inside the outer edge of the membrane electrode assembly 12.

[0013] The outer edge of the membrane electrode assembly 12, i.e., the left edge in FIG. 1, protrudes outward from the outer edge of the gas diffusion layer 13. An insulating sheet 14 is disposed on both sides of the outer edge of the membrane electrode assembly 12 in the thickness direction. The insulating sheet 14 is attached to the outer edge of the membrane electrode assembly 12 by an adhesive layer 16. The membrane electrode assembly 12, the gas diffusion layer 13, and the insulating sheet 14 are sandwiched between plate-shaped separators 15 on both sides in the thickness direction. The separators 15 are formed of a conductive material such as stainless steel, titanium, or carbon. The insulating sheet 14 is attached to the outer edge of the separator 15 by an adhesive layer 16 that is different from the adhesive layer 16. The insulating sheet 14 is formed of an insulating material such as resin or rubber.

[0014] When a cell stack is formed by stacking a plurality of fuel cells 11 in the thickness direction, the separator 15 presses the membrane electrode assembly 12, the gas diffusion layer 13, and the insulating sheet 14 by sandwiching them from both sides in the thickness direction. The separator 15 in contact with the gas diffusion layer 13 on the anode electrode layer 18 side forms a flow path 20 between the separator 15 and the gas diffusion layer 13 for flowing a fuel gas such as hydrogen. The separator 15 in contact with the gas diffusion layer 13 on the cathode electrode layer 19 side forms a flow path 21 between the separator 15 and the gas diffusion layer 13 for flowing an oxidizing gas such as air. When the fuel gas flows through the flow path 20, it is diffused in the gas diffusion layer 13 and then supplied to the anode electrode layer 18. When the oxidizing gas flows through the flow path 21, it is diffused in the gas diffusion layer 13 and then supplied to the cathode electrode layer 19. Then, power is generated based on the reaction between the fuel gas and the oxidizing gas in the membrane electrode assembly 12.

[0015] <Adhesive layer 16> Next, the adhesive layer 16 will be described in detail. As shown in FIG. 2, the adhesive layer 16 is formed of an adhesive 23 mixed with a large number of spacers 22. The spacers 22 are granular. When the separator 15 presses the membrane electrode assembly 12, the gas diffusion layer 13, and the insulating sheet 14 from both sides in the thickness direction as the cell stack is formed, the thickness of the adhesive layer 16 becomes thinner and the membrane electrode assembly 12 and the gas diffusion layer 13 are crushed to some extent in the thickness direction by the pressure. The spacers 22 mixed into the adhesive 23 forming the adhesive layer 16 are made of a material having a strength that does not collapse due to the pressure when the separator 15 presses the membrane electrode assembly 12, the gas diffusion layer 13, and the insulating sheet 14 by sandwiching them from both sides in the thickness direction.

[0016] The particle size of the spacers 22 is determined so that when the separators 15 apply pressure by sandwiching the membrane electrode assembly 12, the gas diffusion layer 13, and the insulating sheet 14 from both sides in the thickness direction, the amount of crushing of the membrane electrode assembly 12 and the gas diffusion layer 13 due to the pressure will be a target value. In addition, the particle size of the spacers 22 is also determined so that when the separators 15 apply pressure by sandwiching the membrane electrode assembly 12, the gas diffusion layer 13, and the insulating sheet 14 from both sides in the thickness direction, the thickness of the adhesive layer 16 will be a value required for adhesion.

[0017] Next, the effects of the fuel cell 11 of this embodiment will be described. (1) When the separator 15 pressurizes the membrane electrode assembly 12, the gas diffusion layer 13, and the insulating sheet 14 by sandwiching them from both sides in the thickness direction, the thickness of the adhesive layer 16 becomes thinner as the pressure is applied. However, since a large number of spacers 22 are mixed into the adhesive 23 forming the adhesive layer 16, the thickness of the adhesive layer 16 when the thickness of the adhesive layer 16 becomes thinner is adjusted to a thickness corresponding to the size of the spacers 22, i.e., the particle size, as described above. As a result, the amount of crushing of the membrane electrode assembly 12 and the gas diffusion layer 13 at this time is also adjusted to a value corresponding to the particle size of the spacers 22. Therefore, by appropriately changing the particle size of the spacers 22 mixed into the adhesive 23, the thickness of the adhesive layer 16 and the amount of crushing of the membrane electrode assembly 12 and the gas diffusion layer 13 can be appropriately adjusted as follows. That is, the thickness of the adhesive layer 16 can be adjusted to a value appropriate for adhesion by the adhesive layer 16, and the amount of crushing of the membrane electrode assembly 12 and the gas diffusion layer 13 can be adjusted to a value appropriate for reducing the electrical resistance in the fuel cell 11.

[0018] (2) The spacers 22 are made of a material having a strength that will not be crushed by pressure when the separators 15 sandwich the membrane electrode assembly 12, the gas diffusion layer 13, and the insulating sheet 14 from both sides in the thickness direction and apply pressure. Therefore, when the adhesive layer 16 becomes thinner due to the above pressure, even if a force caused by the above pressure acts on the spacers 22 mixed in the adhesive 23 forming the adhesive layer 16, the spacers 22 will not be crushed. Therefore, it is possible to prevent the adhesive layer 16 from becoming thinner than a value corresponding to the particle size of the spacers 22 due to the crushing of the spacers 22, and to prevent the amount of crushing of the membrane electrode assembly 12 and the gas diffusion layer 13 in the thickness direction from exceeding a value corresponding to the particle size of the spacers 22.

[0019] (3) When the separator 15 presses the membrane electrode assembly 12, the gas diffusion layer 13, and the insulating sheet 14 by sandwiching them from both sides in the thickness direction, the spacers 22 may be aligned in the direction in which the force accompanying the pressurization acts. Even in this case, since the spacers 22 are granular, the spacers 22 spread in a direction perpendicular to the direction in which the force acts as the force acts. Since the spacers 22 do not line up in the direction in which the force acts, the thickness of the adhesive layer 16 and the amount of crushing of the membrane electrode assembly 12 and the gas diffusion layer 13 can be appropriately adjusted by appropriately changing the particle size of the spacers 22 mixed into the adhesive 23.

[0020] (4) The particle size of the spacers 22 is determined so that when the separators 15 pressurize the membrane electrode assembly 12, the gas diffusion layer 13, and the insulating sheet 14 by sandwiching them from both sides in the thickness direction, the amount of crushing of the membrane electrode assembly 12 and the gas diffusion layer 13 due to the pressurization is a target value. The target value of the amount of crushing of the membrane electrode assembly 12 and the gas diffusion layer 13 at this time is considered to be a value appropriate for reducing the electrical resistance in the fuel cell 11. By determining the particle size of the spacers 22 so as to realize such a target value of the amount of crushing, it is possible to realize a reduction in the electrical resistance in the fuel cell 11 when the pressurization is performed.

[0021] (5) The particle size of the spacers 22 is determined so that the thickness of the adhesive layer 16 becomes a value required for adhesion when the separator 15 sandwiches and pressurizes the membrane electrode assembly 12, the gas diffusion layer 13, and the insulating sheet 14 from both sides in the thickness direction. This ensures the adhesiveness required for the adhesive layer 16 when pressurized.

[0022] The above embodiment can be modified, for example, as follows: The above embodiment and the following modified examples can be combined with each other to the extent that no technical contradiction occurs. 3, plates 24 harder than the membrane electrode assembly 12 and the insulating sheet 14 may be fixed to the locations of the membrane electrode assembly 12 corresponding to the adhesive layer 16 and the insulating sheet 14 corresponding to the adhesive layer 16, respectively. In this case, when the separator 15 presses the membrane electrode assembly 12, the gas diffusion layer 13, and the insulating sheet 14 by sandwiching them from both sides in the thickness direction, it is possible to prevent the membrane electrode assembly 12 and the insulating sheet 14 from being dented by the spacers 22.

[0023] The particle size of the spacers 22 is determined so that the thickness of the adhesive layer 16 becomes a value required for adhesion when pressure is applied by the separator 15, but this is not essential. The particle size of the spacers 22 is determined so that the amount of crushing of the membrane electrode assembly 12 and the gas diffusion layer 13 when pressed by the separator 15 is a target value, but this is not essential.

[0024] The spacer 22 does not necessarily have to be granular, but may be, for example, fibrous. Next, the technical concept that can be understood from the above embodiment will be described. (A) The fuel cell comprises a membrane electrode assembly, a gas diffusion layer, an insulating sheet, a separator, and an adhesive layer, the insulating sheets are disposed on both sides in a thickness direction of the outer edge of the membrane electrode assembly, the gas diffusion layers are disposed on both sides of the membrane electrode assembly in a thickness direction on the inner side of an outer edge of the membrane electrode assembly, the separator presses the membrane electrode assembly, the gas diffusion layer, and the insulating sheet by sandwiching them from both sides in a thickness direction; A fuel cell in which the adhesive layer is formed between the separator and the insulating sheet, and between the insulating sheet and the outer edge of the membrane electrode assembly, using an adhesive having a large number of spacers mixed in.

[0025] (B) The fuel cell described in (A), wherein the spacer is formed of a material having a strength such that it will not be crushed by pressure when the separator sandwiches the membrane electrode assembly, the gas diffusion layer, and the insulating sheet from both sides in the thickness direction and applies pressure thereto.

[0026] (C) The fuel cell according to (B), wherein the spacer is granular. (D) The fuel cell described in (C), wherein the particle size of the spacer is determined so that when the separator sandwiches and pressurizes the membrane electrode assembly, the gas diffusion layer, and the insulating sheet from both sides in the thickness direction, the amount of crushing of the membrane electrode assembly and the gas diffusion layer due to the pressurization reaches a target value.

[0027] (E) A fuel cell described in (C) or (D), wherein the particle size of the spacer is determined so that when the separator sandwiches and pressurizes the membrane electrode assembly, the gas diffusion layer, and the insulating sheet from both sides in the thickness direction, the thickness of the adhesive layer becomes a value required for adhesion. [Explanation of symbols]

[0028] 11...Fuel cell 12...Membrane electrode assembly 13...Gas diffusion layer 14…Insulating sheet 15…Separator 16...adhesive layer 17...Electrolyte membrane 18...Anode electrode layer 19…Cathode electrode layer 20...Flow path 21...Flow path 22…Spacer 23...Glue 24…Plate

Claims

1. The fuel cell comprises a membrane electrode assembly, a gas diffusion layer, an insulating sheet, a separator, and an adhesive layer, the insulating sheets are disposed on both sides in a thickness direction of the outer edge of the membrane electrode assembly, the gas diffusion layers are disposed on both sides of the membrane electrode assembly in a thickness direction on the inner side of an outer edge of the membrane electrode assembly, the separator presses the membrane electrode assembly, the gas diffusion layer, and the insulating sheet by sandwiching them from both sides in a thickness direction; A fuel cell in which the adhesive layer is formed between the separator and the insulating sheet, and between the insulating sheet and the outer edge of the membrane electrode assembly, using an adhesive having a large number of spacers mixed in.

2. 2. The fuel cell according to claim 1, wherein the spacer is formed of a material having a strength sufficient to not be crushed by pressure applied when the separator sandwiches the membrane electrode assembly, the gas diffusion layer, and the insulating sheet from both sides in the thickness direction.

3. The fuel cell according to claim 2 , wherein the spacer is granular.

4. 4. The fuel cell according to claim 3, wherein the particle size of the spacers is determined so that when the separator sandwiches and pressurizes the membrane electrode assembly, the gas diffusion layer, and the insulating sheet from both sides in the thickness direction, the amount of crushing of the membrane electrode assembly and the gas diffusion layer due to the pressurization reaches a target value.

5. 4. The fuel cell according to claim 3, wherein the particle size of the spacers is determined so that when the separator presses the membrane electrode assembly, the gas diffusion layer, and the insulating sheet by sandwiching them from both sides in the thickness direction, the thickness of the adhesive layer becomes a value required for adhesion.

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