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 Art

[0002] Various technologies have been proposed regarding fuel cells as disclosed in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 discloses a fuel cell stack in which a drain pipe for sucking and removing stored water is provided inside at least one of a reaction gas inlet manifold or a reaction gas outlet manifold. Since an end separator (end plate) exists at the end of the manifold, there is a possibility that the outlet of the drain pipe adheres to the end separator and drainage performance cannot be ensured.

[0005] The present disclosure has been made in view of the above circumstances, and the main object thereof is to provide a fuel cell stack capable of improving drainage performance.

Means for Solving the Problems

[0006] That is, the present disclosure includes the following aspects. <1> A fuel cell stack including a plurality of stacked fuel cells and an end plate disposed at an end in the stacking direction of the fuel cells, where the fuel cell stack includes a manifold that penetrates the fuel cells in the stacking direction of the fuel cells, The manifold comprises a drain pipe located inside the manifold, The fuel cell stack is characterized in that the end plate has a protrusion that faces the end of the drain pipe and does not seal the end of the drain pipe. [Effects of the Invention]

[0007] The fuel cell stack of this disclosure can improve drainage. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows (1) a schematic diagram illustrating an example of a part of a fuel cell stack in this disclosure, (2) a schematic diagram illustrating an example of the AA cross-section of (1), and (3) a schematic diagram illustrating an example of the BB cross-section of (2). [Figure 2] Figure 2 shows (1) a schematic diagram illustrating an example of a part of a conventional fuel cell stack, and (2) a schematic diagram illustrating an example of the AA cross-section of (1). [Figure 3] Figure 3 is a graph showing an example of the relationship between the amount of water stored and the reservoir pore. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure are described below. Matters other than those specifically mentioned herein but necessary for the implementation of this disclosure (e.g., general configuration and manufacturing processes of fuel cell stacks not characterizing this disclosure) can be understood as design matters for those skilled in the art based on prior art. This disclosure can be implemented based on the content disclosed herein and common technical knowledge in the art. Furthermore, the dimensions (length, width, thickness, etc.) shown in the diagram do not necessarily reflect the actual dimensions. In this 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 oxidizer gas (cathode gas). The fuel gas is mainly a gas containing hydrogen, but may also be hydrogen. The oxidizer gas is a gas containing oxygen, but may also be oxygen, air, etc. In this disclosure, the fuel gas and the oxidizer gas are collectively referred to as the reaction gas or gas.

[0010] This disclosure provides a fuel cell stack comprising a plurality of stacked fuel cell cells and end plates disposed at the ends of the stacking direction of the fuel cell cells, The fuel cell stack includes a manifold that penetrates the fuel cell cells in the stacking direction of the fuel cell cells, The manifold comprises a drain pipe located inside the manifold, The end plate is provided with a protrusion that faces the end of the drain pipe and does not seal the end of the drain pipe, thereby providing a fuel cell stack.

[0011] In this disclosure, a structure is created to ensure drainage functionality by providing a certain gap at the end of the drain pipe for draining generated water from within the fuel cell stack. In this disclosure, by providing a protrusion 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 will come into contact with a protrusion (structure such as a rib) that does not seal the tip of the drain structure, thereby ensuring a gap for drainage.

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

[0013] The cell may have a power generation unit. The shape of the power generation unit may be rectangular in plan view. The power generation unit 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 fluorine-based electrolyte membranes such as thin films of perfluorosulfonic acid containing moisture, and hydrocarbon-based electrolyte membranes. 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 (oxidant electrode). The electrode includes a catalyst layer and may optionally include a gas diffusion layer. The power generation unit may be a membrane electrode gas diffusion layer assembly (MEGA). The catalyst layer includes a catalyst, and the catalyst may include a catalyst metal that promotes an electrochemical reaction, an electrolyte having proton conductivity, and a carrier having electron conductivity. As the catalyst metal, for example, platinum (Pt) and alloys composed of Pt and other metals (for example, Pt alloys mixed with cobalt, nickel, etc.) can be used. The catalyst metal used as the cathode catalyst and the catalyst metal used as the anode catalyst may be the same or different. The electrolyte may be a fluorine-based resin or the like. As the fluorine-based resin, for example, a Nafion solution or the like may be used. The above catalyst metal is supported on a carrier, and in each catalyst layer, the carrier supporting the catalyst metal (catalyst-supported carrier) and the electrolyte may be mixed. Examples of the carrier for supporting the catalyst metal include carbon materials such as generally commercially available carbon. The gas diffusion layer may be a conductive member having pores. Examples of the conductive member include carbon porous bodies such as carbon cloth and carbon paper, and metal porous members such as metal mesh and foamed metal. The fuel cell may include a separator. The separator collects the current generated by power generation and functions as a partition. In a fuel cell, the separator is usually arranged on both sides in the stacking direction of the power generation part so that a pair of separators sandwich the power generation part. One of the pair of separators is an anode separator and the other is a cathode separator. The anode separator may have grooves serving as fuel gas flow paths on the surface on the power generation part side. The cathode separator may have grooves serving as oxidant gas flow paths on the surface on the power generation part side. The separator may have holes that constitute a manifold such as supply holes and discharge holes for allowing a fluid to flow in the stacking direction of the cell. Examples of the separator may include dense carbon obtained by compressing carbon to make it gas-impermeable, and press-molded metals (e.g., iron, titanium, stainless steel, etc.). The cell may include an insulating resin frame arranged on the outer side (outer periphery) in the plane direction of the membrane electrode assembly between the anode separator and the cathode separator. The resin frame is molded using a thermoplastic resin to form a plate-like and frame-like shape, and seals the space between the anode separator and the cathode separator while holding the membrane electrode assembly in its central region. As the resin frame, for example, resins such as PE, PP, PET, PEN, etc. can be used. The resin frame may be a three-layer sheet composed of three layers with an adhesive layer arranged on the surface layer.

[0014] The fuel cell stack includes a manifold that penetrates the fuel cell in the stacking direction of the fuel cells. The manifold may be a reaction gas inlet manifold, a reaction gas outlet manifold, or both of them. The reaction gas inlet manifold may be a fuel gas inlet manifold, an oxidant gas inlet manifold, or both of them. The reaction gas outlet manifold may be a fuel gas outlet manifold, an oxidant gas outlet manifold, or both of them. In other words, the manifold consists of a fuel gas inlet manifold, an oxidizer gas inlet manifold, It may be at least one of the fuel gas outlet manifold and the oxidizer gas outlet manifold, or all of them. The fuel cell stack includes a drain pipe located inside the manifold.

[0015] End plates (end separators) are positioned at the ends of the fuel cell stack in the stacking direction of the fuel cell cells. The end plates only need to be positioned at at least one end of the stacking direction of the fuel cell cells in the fuel cell stack, and may be positioned 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 the end of the drain pipe and does not seal the end of the drain pipe. If the fuel cell stack has a pair of end plates, one of the pair of end plates, the first end plate, may have a first protrusion that faces one of the first ends of the drain pipe. Also, the other of the pair of end plates, the second end plate, may have a second protrusion that faces the other of the second ends of the drain pipe. From the viewpoint of not sealing the end of the drainpipe, the cross-sectional area of ​​the protrusion may be smaller than the cross-sectional area of ​​the drainpipe. The height of the protrusion can be set appropriately, taking drainage into consideration. The end plates can be made of the same materials as those exemplified in the separator.

[0016] The fuel cell stack may have gaskets, resin sheets, etc., for sealing the gases between cells and between cells and end plates.

[0017] Figure 1 shows (1) a schematic diagram illustrating an example of a part of a fuel cell stack in this disclosure, (2) a schematic diagram illustrating an example of the AA cross-section of (1), and (3) a schematic diagram illustrating an example of the BB cross-section of (2). The fuel cell stack 100 shown in Figure 1(1) is a stack in which multiple cells 10 are stacked with gaskets 30 in between, as shown in Figure 1(2). End plates 11 are located at the ends of the cells 10 in the stacking direction, and a drain pipe 20 is located inside the manifold. The end plate 11 is provided with a protrusion 12 at a position opposite to the end of the drain pipe 20, such that the end of the drain pipe 20 is not sealed. As shown in Figure 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 protrusion 12 within the range of the drain pipe 20 that does not seal the tip of the drain pipe 20, the water storage gap can be reduced, and drainage performance can be improved.

[0018] Figure 2 shows (1) a schematic diagram illustrating an example of a part of a conventional fuel cell stack, and (2) a schematic diagram illustrating an example of the AA cross-section of (1). The conventional fuel cell stack 200 shown in Figure 2 is the same as in Figure 1, except that the end plate 11 does not have a protrusion 12 in a position opposite to the drain pipe 20, as shown in Figure 2(2). The absence of the protrusion 12 results in a larger water reservoir gap compared to the case where the protrusion 12 is present, leading to poorer drainage. Furthermore, to ensure proper drainage, it becomes necessary to place another component.

[0019] Figure 3 is a graph showing an example of the relationship between the amount of water stored and the reservoir pore. It was confirmed that as the water reservoir gap increases, the amount of water stored increases and the drainage performance decreases. Furthermore, it was confirmed that by providing a predetermined protrusion that satisfies the conditions of this disclosure at a position on the end plate facing the drain pipe, the amount of water stored is reduced to about one-quarter compared to when the protrusion is not provided, and the drainage performance is 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 cell cells and end plates positioned at the ends of the fuel cell cells in the stacking direction, The fuel cell stack includes a manifold that penetrates the fuel cell cells in the stacking direction of the fuel cell cells, The manifold comprises a drain pipe located inside the manifold, The fuel cell stack is characterized in that the end plate has a protrusion that faces the end of the drain pipe and does not seal the end of the drain pipe.

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