Fuel cell stack

Abstract

To provide a fuel cell stack which can be improved in drainage.SOLUTION: A fuel cell stack is provided, comprising a plurality of laminated fuel cells and an end plate arranged in an end in the lamination direction, of the fuel cell. The fuel cell stack comprises a manifold penetrating through the fuel cell stack in the lamination direction of the fuel cells, and a drain pipe arranged inside the manifold. The end plate faces the end of the drain pipe, and has a protrusion having a shape not tightly sealing the end of the drain pipe.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a fuel cell stack. [Background technology]

[0002] Various techniques have been proposed regarding fuel cells such as that disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-190358 A Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses a fuel cell stack structure in which a drain pipe for suctioning and removing accumulated water is provided inside at least one of the reactant gas inlet manifold and the reactant gas outlet manifold. Since an end separator (end plate) is present at the end of the manifold, the outlet of the drain pipe may come into close contact with the end separator, making it impossible to ensure drainage.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and has as its main object to provide a fuel cell stack capable of improving drainage performance. [Means for solving the problem]

[0006] That is, the present disclosure includes the following aspects. <1> A fuel cell stack comprising a plurality of stacked fuel cells and an end plate disposed at an end of the fuel cells in a stacking direction, The fuel cell stack includes a manifold that penetrates the fuel cell in a stacking direction of the fuel cell; a drain pipe disposed inside the manifold; 2. A fuel cell stack comprising: an end plate having a protrusion that faces an end of the drain pipe and that is shaped so as not to seal the end of the drain pipe. Effect of the Invention

[0007] The fuel cell stack of the present disclosure can improve drainage. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 (1) is a schematic diagram showing an example of a portion of a fuel cell stack in the present disclosure, (2) is a schematic diagram showing an example of an AA cross section of (1), and (3) is a schematic diagram showing an example of a BB cross section of (2). [Diagram 2] FIG. 2(1) is a schematic diagram showing an example of a part of a conventional fuel cell stack, and (2) is a schematic diagram showing an example of a cross section taken along line AA of (1). [Diagram 3] FIG. 3 is a graph showing an example of the relationship between the amount of stored water and the water storage gap. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described. Note that matters other than those specifically mentioned in this specification and necessary for implementing the present disclosure (for example, the general configuration and manufacturing process of a fuel cell stack that do not characterize the present disclosure) can be understood as design matters of a person skilled in the art based on the prior art in the field. The present disclosure can be implemented based on the contents disclosed in this specification and the technical common sense in the field. Furthermore, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect the actual dimensional relationships. In the present disclosure, the gas supplied to the anode of the fuel cell is the fuel gas (anode gas), and the gas supplied to the cathode of the fuel cell is the oxidant gas (cathode gas). The fuel gas is a gas that contains mainly hydrogen and may be hydrogen. The oxidant gas is a gas that contains oxygen and may be oxygen, air, etc. In the present disclosure, the fuel gas and the oxidant gas are collectively referred to as reactant gases or gases.

[0010] The present disclosure provides a fuel cell stack including a plurality of stacked fuel cell units and end plates disposed at ends of the fuel cell units in a stacking direction, The fuel cell stack includes a manifold that penetrates the fuel cell in a stacking direction of the fuel cell; a drain pipe disposed inside the manifold; The end plate has a protrusion that faces the end of the drain pipe and is shaped so as not to seal the end of the drain pipe.

[0011] In this disclosure, a structure is created that provides a certain gap at the end of the drain pipe for draining generated water from within the fuel cell stack, ensuring the drainage function. In this disclosure, by providing a convex portion on the end plate (end separator) that faces the end of the drain pipe, even if the end of the drain pipe (straw, etc.) tries to make close contact with the end plate, it hits a convex portion (rib, etc. structure) that does not seal the tip of the drainage structure, ensuring a gap for drainage.

[0012] The fuel cell stack (stack) of the present disclosure includes a plurality of stacked fuel cells (cells, single cells) and end plates disposed at ends of the fuel cells in the stacking direction. In this disclosure, both fuel cells and fuel cell stacks may be referred to as fuel cells. The number of cells stacked in the fuel cell stack is not particularly limited, and may be, for example, from 2 to several hundred.

[0013] The cell may have a power generation portion. The power generating section may have a rectangular shape in a plan view. The power generating section may be a membrane electrode assembly (MEA) including an electrolyte membrane and two electrodes. The electrolyte membrane may be a solid polymer electrolyte membrane. Examples of the solid polymer electrolyte membrane include a fluorine-based electrolyte membrane such as a thin film of perfluorosulfonic acid containing water, and a hydrocarbon-based electrolyte membrane. The electrolyte membrane may be, for example, a Nafion membrane (manufactured by DuPont). One of the two electrodes is an anode (fuel electrode) and the other is a cathode (oxidizer electrode). The electrodes include a catalyst layer and may include a gas diffusion layer as necessary, and the power generating portion may be a membrane electrode gas diffusion layer assembly (MEGA). The catalyst layer includes a catalyst, and the catalyst may include a catalytic metal that promotes an electrochemical reaction, an electrolyte having proton conductivity, and a carrier having electron conductivity. Examples of the catalytic metal that can be used include platinum (Pt) and alloys of Pt with other metals (e.g., Pt alloys mixed with cobalt and nickel, etc.) The catalytic metal used as the cathode catalyst and the catalytic metal used as the anode catalyst may be the same or different. The electrolyte may be a fluorine-based resin, etc. As the fluorine-based resin, for example, a Nafion solution, etc. may be used. The catalytic metal is supported on a carrier, and in each catalyst layer, the carrier supporting the catalytic metal (catalyst-supporting carrier) and the electrolyte may be mixed. The support for supporting the catalytic metal may be, for example, a carbon material such as carbon that is generally available commercially. The gas diffusion layer may be a conductive member having air holes. Examples of the conductive member include porous carbon materials such as carbon cloth and carbon paper, and porous metal members such as metal mesh and foamed metal. The fuel cell may include a separator. The separators collect the electric current generated by power generation and function as partition walls. In a fuel cell, the separators are usually arranged on both sides of the power generation section in the stacking direction so that the power generation section is sandwiched between a pair of separators. One of the pair of separators is an anode separator and the other is a cathode separator. The anode separator may have grooves that serve as fuel gas flow paths on the surface facing the power generation section. The cathode separator may have grooves that serve as oxidant gas flow paths on the surface facing the power generation section. The separator may have holes forming manifolds such as supply holes and discharge holes for circulating a fluid in the stacking direction of the cells. The separator may be made of, for example, dense carbon obtained by compressing carbon to make it gas impermeable, or a press-molded metal (for example, iron, titanium, stainless steel, etc.). The cell may include an insulating resin frame disposed on the outer side (periphery) of the membrane electrode assembly in the planar direction between the anode separator and the cathode separator. The resin frame is molded into a plate-like and frame-like shape using a thermoplastic resin, and seals the gap between the anode separator and the cathode separator while holding the membrane electrode assembly in its central region. For the resin frame, for example, a resin such as PE, PP, PET, or PEN can be used. The resin frame may be a three-layer sheet composed of three layers with an adhesive layer disposed on the surface layer.

[0014] The fuel cell stack includes a manifold that passes through the fuel cells in the stacking direction of the fuel cells. The manifold may be a reactant gas inlet manifold, a reactant gas outlet manifold, or both. The reactant gas inlet manifold may be a fuel gas inlet manifold, an oxidant gas inlet manifold, or both. The reactant gas outlet manifold may be a fuel gas outlet manifold, an oxidant gas outlet manifold, or both. That is, the manifold includes a fuel gas inlet manifold, an oxidant gas inlet manifold, At least one of the fuel gas outlet manifold and the oxidant gas outlet manifold may be used, or all of them may be used. The fuel cell stack includes a drain disposed within the manifold.

[0015] The end plate (end separator) is disposed at an end of the fuel cell stack in the stacking direction of the fuel cell cells. The end plate needs to be disposed at at least one end of the fuel cell stack in the stacking direction of the fuel cell cells, and may be disposed at both ends. The fuel cell stack may include a pair of end plates that sandwich the stack of fuel cell cells. The end plate has a protrusion that faces an end of the drain pipe and is shaped not to seal the end of the drain pipe. When the fuel cell stack has a pair of end plates, a first end plate of the pair of end plates may have a first protrusion that faces a first end of one of the drain pipes. Also, a second end plate of the pair of end plates may have a second protrusion that faces a second end of the other of the drain pipes. From the viewpoint of providing a shape that does not seal the end of the drain pipe, the cross-sectional area of ​​the convex portion may be smaller than the cross-sectional area of ​​the drain pipe. The height of the convex portion can be appropriately set taking into consideration drainage properties. The end plates can be made of the same materials as those exemplified for the separators.

[0016] The fuel cell stack may have gaskets, resin sheets, and the like between the cells and between the cells and end plates to seal the various gases.

[0017] FIG. 1 (1) is a schematic diagram showing an example of a portion of a fuel cell stack in the present disclosure, (2) is a schematic diagram showing an example of an AA cross section of (1), and (3) is a schematic diagram showing an example of a BB cross section of (2). The fuel cell stack 100 shown in Fig. 1(1) is a stack of multiple cells 10 stacked with gaskets 30 between them as shown in Fig. 1(2), with an end plate 11 at the end of the stacking direction of the cells 10 and a drain pipe 20 disposed within a manifold. The end plate 11 is provided with a protrusion 12 at a position opposite the end of the drain pipe 20, which is structured so that the end of the drain pipe 20 is not sealed. As shown in Fig. 1(3), the cross-sectional area of ​​the protrusion 12 is smaller than the cross-sectional area of ​​the drain pipe 20. By providing a convex portion 12 having a structure in which the tip of the drain pipe 20 is not sealed within the area in which the drain pipe 20 is present, the water storage gap can be made smaller, and drainage performance can be improved.

[0018] FIG. 2(1) is a schematic diagram showing an example of a part of a conventional fuel cell stack, and (2) is a schematic diagram showing an example of a cross section taken along line AA of (1). The conventional fuel cell stack 200 shown in Fig. 2 is similar to that shown in Fig. 1, except that the end plate 11 does not have a protrusion 12 at a position opposite the drain pipe 20, as shown in Fig. 2(2). The absence of the protrusion 12 results in a larger water storage gap and poorer drainage compared to when the protrusion 12 is provided. Also, in order to ensure drainage, it becomes necessary to place another member.

[0019] FIG. 3 is a graph showing an example of the relationship between the amount of stored water and the water storage gap. It was confirmed that the larger the water storage gap, the higher the water storage capacity and the lower the drainage performance. In addition, it was confirmed that by providing a specific convex portion that satisfies the conditions of this disclosure at the position of the end plate facing the drain pipe, the water storage capacity was reduced to about one-fourth compared to when the convex portion was not provided, and the drainage performance was improved. [Explanation of symbols]

[0020] 10. Cell 11. End Plate 12. Convex part 20. Drain pipe 30. Gasket 100. Fuel cell stack 200. Fuel Cell Stack

Claims

[Claim 1] A fuel cell stack comprising a plurality of stacked fuel cells and an end plate disposed at an end of the fuel cells in a stacking direction, The fuel cell stack includes a manifold that penetrates the fuel cell in a stacking direction of the fuel cell; a drain pipe disposed inside the manifold; 2. A fuel cell stack comprising: an end plate having a protrusion that faces an end of the drain pipe and that is shaped so as not to seal the end of the drain pipe.

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