JP2022165808A - fuel cell stack - Google Patents

Abstract

To provide a fuel cell stack capable of suppressing liquid water from flowing in a film electrode assembly of a power generation cell.SOLUTION: In a fuel cell stack 11, a plurality of power generation cells 12 generating power by using gas is laminated, and a dummy cell 13 which does not generate power is laminated in each power generation cell 12 positioned at one end part in a lamination direction X of the plurality of power generation cells 12. Each power generation cell 12 comprises: a support frame 19 that supports a film electrode assembly 18; and a pair of separators 20 nipping the support frame 19. In each power generation cell 12 and the dummy cell 13, a fuel gas supply hole 21 for forming a fuel gas supply passage 28 extending in the lamination direction X and to which fuel gas is supplied is formed. A passage formation hole 22 forming a passage 29 extending in the lamination direction X is formed between the fuel gas supply hole 21 and the film electrode assembly 18 in each power generation cell 12. The passage 29 is communicated with both of the fuel gas supply passage 28 and the film electrode assembly 18.SELECTED DRAWING: Figure 1

Description

The present invention relates to fuel cell stacks.

2. Description of the Related Art Conventionally, as a fuel cell stack, for example, the one disclosed in Patent Document 1 is known. Such a fuel cell stack is formed by stacking a plurality of power generation cells in its thickness direction. Each power generation cell includes an electrolyte membrane/electrode assembly, and a first metal separator and a second metal separator sandwiching the electrolyte membrane/electrode assembly. The electrolyte membrane/electrode assembly includes a solid polymer electrolyte membrane, and an anode-side electrode and a cathode-side electrode that sandwich the solid polymer electrolyte membrane.

At one end edge of each power generation cell, an oxidant gas inlet communication hole for supplying an oxidant gas, for example, an oxygen-containing gas, and a fuel, for example, a hydrogen-containing gas, are provided in communication with each other in the stacking direction. A fuel gas outlet passage is provided for discharging the gas. The other edge of each power generation cell is provided with an oxidant gas outlet communication hole for discharging the oxidant gas and a fuel gas inlet communication hole for supplying the fuel gas, which communicate with each other in the stacking direction. there is

An oxidant gas channel is provided on the surface of the second metal separator on the electrolyte membrane/electrode assembly side. The oxidant gas channel communicates the oxidant gas inlet communication hole and the oxidant gas outlet communication hole. A fuel gas flow path is provided on the surface of the first metal separator on the electrolyte membrane electrode assembly side. Furthermore, the first metal separator is provided with a plurality of supply holes and a plurality of discharge holes. The plurality of supply holes communicate the fuel gas inlet communication hole and the fuel gas flow path. The plurality of discharge holes communicate the fuel gas flow path and the fuel gas outlet communication hole.

When power is generated by the fuel cell stack, first, the oxidant gas is supplied from the oxidant gas inlet communication hole, and the fuel gas is supplied from the fuel gas inlet communication hole. The oxidizing gas is introduced from the oxidizing gas inlet communication hole into the oxidizing gas channel of the second metal separator and supplied to the cathode side electrode of the electrolyte membrane electrode assembly. The fuel gas is introduced from the fuel gas inlet communication hole through the supply hole into the fuel gas channel of the first metal separator and supplied to the anode side electrode of the electrolyte membrane electrode assembly. Electricity is generated based on the electrochemical reaction between the fuel gas and the oxidant gas in the electrolyte membrane/electrode assembly.

JP 2006-147502 A

By the way, in the fuel cell stack as described above, unreacted fuel gas is recovered and reused. This reused fuel gas contains liquid water generated during power generation. As a result, fuel gas containing liquid water is supplied to the anode side electrode of the electrolyte membrane electrode assembly. As a result, there is a problem that the electrochemical reaction of the fuel gas in the electrolyte membrane/electrode assembly is inhibited by the liquid water and the voltage drops.

Means for solving the above problems and their effects will be described below.
A fuel cell stack that solves the above-mentioned problems is provided by stacking a plurality of power generation cells that generate power using gas, and a dummy cell that does not generate power is stacked on the power generation cell positioned at one end in the stacking direction of the plurality of power generation cells. In the fuel cell stack, each power generation cell includes a support frame that supports a membrane electrode assembly, and a pair of separators that sandwich the support frame, and each power generation cell and the dummy cell are provided in the stacking direction. A first hole extending to form a gas manifold to which the gas is supplied is formed, and a passage extending in the stacking direction is formed between the first hole and the membrane electrode assembly in each power generation cell. A second hole is formed, and the passage communicates with both the gas manifold and the membrane electrode assembly.

According to this configuration, when the gas is vigorously supplied from the side opposite to the dummy cell side of the gas manifold, liquid water (water vapor) contained in the gas is flown through the gas manifold to the dummy cells by the force of the gas and separated. . The gas from which the liquid water is separated is supplied to the membrane electrode assembly of each power generating cell located on the front side (upstream side) of the dummy cell through the passage. Therefore, it is possible to suppress liquid water from flowing to the membrane electrode assembly of each power generation cell.

1 is an end view of an embodiment fuel cell stack; FIG. FIG. 2 is an exploded perspective view of a power generation cell; FIG. 4 is a front view showing shapes of a fuel gas supply hole and a passage forming hole; FIG. 3 is an exploded perspective view of a dummy cell; FIG. 4 is an enlarged end view of a main part showing the flow of fuel gas in the fuel cell stack; The front view which shows the shape of the fuel gas supply hole of a modification, and a channel|path formation hole. FIG. 11 is a front view showing the shapes of fuel gas supply holes and passage forming holes in another modified example;

An embodiment of a fuel cell stack will be described below with reference to the drawings.
As shown in FIG. 1, the fuel cell stack 11 includes a plurality of rectangular plate-shaped power generation cells 12 that generate power using, for example, a fuel gas containing hydrogen and an oxidant gas containing, for example, oxygen, and one rectangular plate-shaped power generation cell 12 that does not generate power. It comprises a cell stack 14 in which dummy cells 13 are stacked in their thickness direction. The dummy cell 13 is stacked on the power generation cell 12 positioned at one end of the plurality of power generation cells 12 in the stacking direction X. As shown in FIG. That is, the dummy cell 13 is located at one end of the cell stack 14 in the stacking direction X. As shown in FIG. End plates 17 are arranged at both ends of the cell stack 14 in the stacking direction X via terminal plates 15 for current collection and insulating plates 16 for insulation.

As shown in FIGS. 1 and 2, each power generating cell 12 is made of synthetic resin and has a frame-like shape and supports a rectangular sheet-like membrane electrode assembly 18 (MEA: Membrane Electrode Assembly) in the central opening. and a pair of metal separators 20 sandwiching the membrane electrode assembly 18 and the support frame 19 in the thickness direction. In each power generation cell 12, fuel gas is supplied to one side (anode side) of the membrane electrode assembly 18 in the thickness direction, and fuel gas is supplied to the other side (cathode side) of the membrane electrode assembly 18 in the thickness direction. When the oxidant gas is supplied, electric power is generated based on the electrochemical reaction of the fuel gas and the oxidant gas in the membrane electrode assembly 18 .

At both ends in the longitudinal direction of each power generation cell 12, that is, at both ends in the longitudinal direction of each support frame 19 and each separator 20, a fuel gas supply hole 21 as an example of a first hole and a passageway as an example of a second hole are provided. A formation hole 22, a fuel gas discharge hole 23, an oxidizing gas supply hole 24, an oxidizing gas discharge hole 25, a cooling medium supply hole 26, and a cooling medium discharge hole 27 are formed through. Each fuel gas supply hole 21 extends in the stacking direction X to form a fuel gas supply passage 28 as an example of a gas manifold to which fuel gas as an example of gas is supplied.

Each passage forming hole 22 forms a passage 29 extending in the stacking direction X and arranged between the fuel gas supply hole 21 and the membrane electrode assembly 18 . The passage 29 is arranged between the fuel gas supply passage 28 and each membrane electrode assembly 18 and communicates with both the fuel gas supply passage 28 and the membrane electrode assemblies 18 .

As shown in FIG. 3, each fuel gas supply hole 21 and each passage forming hole 22 are arranged adjacent to each other. As an example, each fuel gas supply hole 21 in this embodiment has an elliptical shape. Each passage forming hole 22 in the present embodiment is L-shaped, for example. The area of the fuel gas supply hole 21 is smaller than that of the passage forming hole 22 .

As shown in FIGS. 1 and 2, each fuel gas discharge hole 23 forms a fuel gas discharge passage 30 extending in the stacking direction X and through which the fuel gas is discharged. Each oxidant gas supply hole 24 extends in the stacking direction X to form an oxidant gas supply passage (not shown) through which the oxidant gas is supplied. Each oxidant gas discharge hole 25 extends in the stacking direction X to form an oxidant gas discharge passage (not shown) through which the oxidant gas is discharged. Each cooling medium supply hole 26 extends in the stacking direction X to form a cooling medium supply passage (not shown) to which a cooling medium such as cooling water is supplied. Each cooling medium discharge hole 27 extends in the stacking direction X to form a cooling medium discharge passage (not shown) through which the cooling medium is discharged.

As shown in FIGS. 1 and 4, the dummy cell 13 is the power generation cell 12 in which the membrane electrode assembly 18 is changed to a rectangular sheet-like conductor 31 and the support frame 19 is changed to a dummy frame 32 made of synthetic resin. , and the separator 20 is shared with the power generating cell 12 . That is, the dummy cell 13 has a dummy frame 32 formed in a frame shape and supporting the conductor 31 in the central opening, and a pair of separators 20 sandwiching the conductor 31 and the dummy frame 32 in the thickness direction. there is

The dummy frame 32 is obtained by omitting the passage forming hole 22 from the support frame 19 of the power generating cell 12, and has the same configuration as the support frame 19 except for this. That is, the dummy frame 32 has the fuel gas supply hole 21 formed therein, but does not have the passage forming hole 22 formed therein. Since the dummy cell 13 does not have the membrane electrode assembly 18, it does not generate electricity even if the fuel gas and the oxidant gas are supplied.

As shown in FIG. 1, in the fuel cell stack 11, between the terminal plate 15 and the separator 20, between the dummy frame 32 and the separator 20, between the support frame 19 and the separator 20, and between the separators 20 are: , is sealed by a gasket 33 .

The terminal plate 15, the insulating plate 16, and the end plate 17 located at the end of the fuel cell stack 11 opposite to the dummy cell 13 side in the stacking direction X are provided with a fuel gas supply port 34 and a fuel gas supply port 34 penetrating therethrough. A gas outlet 35 is formed respectively. The fuel gas supply port 34 and the fuel gas discharge port 35 communicate with the fuel gas supply passage 28 and the fuel gas discharge passage 30, respectively. The fuel gas supply port 34 has the same cross-sectional shape and cross-sectional area as the fuel gas supply hole 21 forming the fuel gas supply passage 28 .

The terminal plate 15, the insulating plate 16, and the end plate 17 positioned at the end of the fuel cell stack 11 opposite to the dummy cell 13 side in the stacking direction X are provided with an oxidant gas supply port (illustrated) penetrating therethrough. ) and an oxidant gas outlet (not shown) are formed respectively. The oxidant gas supply port and the oxidant gas discharge port communicate with the oxidant gas supply passage (not shown) and the oxidant gas discharge passage (not shown), respectively.

The terminal plate 15, the insulating plate 16, and the end plate 17, which are located at the end of the fuel cell stack 11 opposite to the dummy cell 13 side in the stacking direction X, are provided with cooling medium supply ports (not shown) penetrating therethrough. ) and a cooling medium outlet (not shown) are formed respectively. The cooling medium supply port and the cooling medium discharge port communicate with the cooling medium supply passage (not shown) and the cooling medium discharge passage (not shown), respectively.

The support frame 19 of each power generation cell 12 has, on the anode side surface (the surface on the dummy cell 13 side in this example), a first communication passage 36 that communicates the passage 29 with the membrane electrode assembly 18, and the membrane electrode assembly 18. and a second communication passage 37 communicating with the fuel gas discharge passage 30 is formed. On the surface of the dummy frame 32 of the dummy cell 13 opposite to the power generation cell 12 side, there are a third communication passage 38 that communicates the fuel gas supply passage 28 and the conductor 31, and the conductor 31 and the fuel gas discharge passage 30. A fourth communication passage 39 is formed to communicate with the .

The support frame 19 of each power generating cell 12 has a cathode-side surface (in this example, the surface opposite to the dummy cell 13 side) on which the membrane electrode assembly 18, the oxidant gas supply passage (not shown), and the oxidizing Two types of communication passages (not shown) are formed to communicate with the agent gas discharge passages (not shown).

Next, the action of the fuel cell stack 11 will be described.
As shown in FIGS. 1 and 5, when the fuel cell stack 11 generates power, fuel gas is vigorously supplied from the fuel gas supply port 34 to the fuel gas supply passage 28 . At this time, the fuel gas contains liquid water W (water vapor). Therefore, the liquid water W passes through the fuel gas supply passage 28 together with a part of the fuel gas due to the inertial force due to the flow of the fuel gas based on its weight, and passes through the dummy frame 32 of the dummy cell 13 opposite to the power generation cell 12 side. It is blown to the side surface and separated.

The separated liquid water W passes through the third communication passage 38, the conductor 31, and the fourth communication passage 39 together with a portion of the fuel gas, and flows into the fuel gas discharge passage 30. It is discharged from the outlet 35 . At this time, the conductor 31 gets wet with the liquid water W, but since the conductor 31 does not generate power, the power generation efficiency of the fuel cell stack 11 is not affected at all.

On the other hand, the fuel gas from which most of the liquid water W has been separated passes from the fuel gas supply passage 28 through the passage 29 and the first communication passage 36 to each power generation cell 12 located on the front side (upstream side) of the dummy cell 13 . is supplied to the anode side surface of the membrane electrode assembly 18 . That is, since the fuel gas containing almost no liquid water W is supplied to the anode-side surface of the membrane electrode assembly 18 of each power generation cell 12, the anode-side surface of the membrane electrode assembly 18 is covered with the liquid water W. Wetting is suppressed. At this time, since the dummy frame 32 does not have the passage forming hole 22 that forms the passage 29, the fuel gas after the liquid water W is separated flows from the passage 29 in the dummy frame 32 opposite to the power generation cell 12 side. It does not flow to the side surface.

Further, on the cathode side surface of the membrane electrode assembly 18 of each power generation cell 12, an oxidizing gas is provided from an oxidant gas supply port (not shown) through an oxidant gas supply passage (not shown) and a communication passage (not shown). Agent gas is supplied. In the fuel cell stack 11, the oxidizing gas supplied to the cathode side surface of the membrane electrode assembly 18 of each power generation cell 12 and the anode side surface of the membrane electrode assembly 18 of each power generation cell 12 are supplied. Electricity is generated based on the electrochemical reaction at the membrane electrode assembly 18 with the fuel gas.

Unreacted fuel gas in the membrane electrode assembly 18 is discharged from the fuel gas discharge port 35 via the second communication passage 37 and the fuel gas discharge passage 30 . Unreacted oxidizing gas in the membrane electrode assembly 18 is discharged from an oxidizing gas supply port (not shown) through a communicating passage (not shown) and an oxidizing gas discharge passage (not shown).

According to the embodiment detailed above, the following effects are exhibited.
(1) In the fuel cell stack 11, a plurality of power generation cells 12 that generate power using fuel gas are stacked, and a dummy cell 13 that does not generate power to the power generation cells 12 positioned at one end of the plurality of power generation cells 12 in the stacking direction X is provided. A stacked cell stack 14 is provided. Each power generation cell 12 includes a support frame 19 supporting a membrane electrode assembly 18 and a pair of separators 20 sandwiching the support frame 19 . Each of the power generation cells 12 and the dummy cells 13 is formed with a fuel gas supply hole 21 extending in the stacking direction X and forming a fuel gas supply passage 28 through which fuel gas is supplied. Between the fuel gas supply hole 21 and the membrane electrode assembly 18 in each power generation cell 12, a passage forming hole 22 that forms a passage 29 extending in the stacking direction X is formed. The passageway 29 communicates with both the fuel gas supply passageway 28 and the membrane electrode assembly 18 .

According to this configuration, when the fuel gas is vigorously supplied from the opposite side of the dummy cell 13 side of the fuel gas supply passage 28, liquid water W (water vapor) contained in the fuel gas is caused to flow into the fuel gas supply passage 28 by the force of the fuel gas. to the dummy cell 13 and separated. The fuel gas from which the liquid water W has been separated is supplied to the membrane electrode assembly 18 of each power generating cell 12 located on the front side (upstream side) of the dummy cell 13 via the passage 29 . Therefore, it is possible to suppress the liquid water W from flowing into the membrane electrode assembly 18 of each power generation cell 12 .

(2) In the fuel cell stack 11 , the area of the fuel gas supply hole 21 is smaller than that of the passage forming hole 22 .
According to this configuration, the flow velocity of the liquid water W contained in the fuel gas flowing through the fuel gas supply passage 28 formed by the plurality of fuel gas supply holes 21 can be increased. Therefore, the liquid water W contained in the fuel gas can be more reliably blown to the dummy cells 13 by the force of the fuel gas supplied to the fuel gas supply passage 28 . Therefore, the liquid water W can be effectively separated from the fuel gas containing the liquid water W.

(Change example)
The above embodiment can be implemented with the following modifications. Moreover, the above embodiments and the following modified examples can be implemented in combination with each other within a technically consistent range.

- As shown in FIG. 6, in the support frame 19 and the separator 20, the fuel gas supply hole 21 may be formed in a triangular shape and the passage forming hole 22 may be formed in a substantially pentagonal shape.
- As shown in FIG. 7, in the support frame 19 and the separator 20, both the fuel gas supply hole 21 and the passage forming hole 22 may be rectangular.

- In the support frame 19 and the separator 20, the fuel gas supply hole 21 and the passage forming hole 22 may be changed into arbitrary shapes.
- The passage forming holes 22 in the separators 20 of the dummy cells 13 may be omitted.

- In the support frame 19 and the separator 20 , the fuel gas supply hole 21 may have the same area as the passage forming hole 22 or may have a larger area than the passage forming hole 22 .
In the fuel cell stack 11, the first hole is the oxidant gas supply hole 24, and the passage 29 is formed so as to communicate the oxidant gas supply passage (not shown) with the membrane electrode assembly 18 of each power generation cell 12. may By doing so, it is possible to effectively suppress the liquid water W contained in the oxidant gas from flowing to the membrane electrode assembly 18, particularly when the oxidant gas is used after being humidified.

- The fuel cell stack 11 may be used in a posture in which the stacking direction X coincides with the vertical direction, or may be used in a posture in which the stacking direction X intersects the vertical direction.

DESCRIPTION OF SYMBOLS 11... Fuel cell stack 12... Power generation cell 13... Dummy cell 14... Cell laminate 15... Terminal plate 16... Insulating plate 17... End plate 18... Membrane electrode assembly 19... Support frame 20... Separator 21... As an example of the 1st hole fuel gas supply hole 22 passage forming hole as an example of the second hole 23 fuel gas discharge hole 24 oxidant gas supply hole 25 oxidant gas discharge hole 26 coolant supply hole 27 coolant discharge hole 28 ... fuel gas supply passage 29 ... passage 30 ... fuel gas discharge passage 31 ... conductor 32 ... dummy frame 33 ... gasket 34 ... fuel gas supply port 35 ... fuel gas discharge port 36 ... first communication passage 37 ... second communication passage 38 ...Third communication path 39...Fourth communication path W...Liquid water X...Lamination direction

Claims (2)

A fuel cell stack in which a plurality of power generation cells that generate power using gas are stacked, and a dummy cell that does not generate power is stacked on the power generation cell positioned at one end in the stacking direction of the plurality of power generation cells,
Each power generation cell includes a support frame that supports a membrane electrode assembly, and a pair of separators sandwiching the support frame,
Each of the power generation cells and the dummy cells is formed with a first hole extending in the stacking direction and forming a gas manifold to which the gas is supplied,
A second hole forming a passage extending in the stacking direction is formed between the first hole and the membrane electrode assembly in each power generation cell,
The fuel cell stack, wherein the passage communicates with both the gas manifold and the membrane electrode assembly. 2. The fuel cell stack of claim 1, wherein the first hole has a smaller area than the second hole.

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