JP2011171027A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress that water resides in the downstream end part of a flow passage for gas supply of a fuel cell. <P>SOLUTION: Respectively on both faces of an electrolyte membrane, the fuel cell includes: a catalyst electrode layer; a gas diffusion layer; and a gas flow passage formation part. At least in one gas flow passage formation part, on a side contacting the gas diffusion layer, along a face of the gas diffusion layer, the gas flow passage of an isolated structure in which the flow passage for gas supply of which the downstream end is closed and the flow passage for gas supply of which the upstream end is closed are alternately arranged by interposing the closed part is formed. This fuel cell has a temperature difference generation structure in which a temperature of the downstream end part of the flow passage for gas supply is higher than that of a flow passage part of gas supply of further upstream than the downstream end part, and than that of an exhaust flow passage part neighboring the downstream end part of the flow passage for gas supply. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solid polymer electrolyte fuel cell, and more particularly to a fuel cell having a structure in which a flow path of a reaction gas is separated for supply and discharge.

A fuel cell is a device that generates electricity by an electrochemical reaction between hydrogen as a fuel gas and oxygen (O ₂ ) as an oxidizing gas. Hereinafter, the fuel gas and the oxidizing gas may be simply referred to as “reaction gas” or “gas” without particular distinction. In this fuel cell, a catalyst electrode layer is bonded to each side of a solid polymer electrolyte membrane (hereinafter, also simply referred to as “electrolyte membrane”) having proton (H ⁺ ) conductivity, and a gas diffusion layer is further arranged. A fuel cell (hereinafter simply referred to as a “cell”) sandwiched by a separator in which a groove as a reaction gas channel is formed on the surface in contact with the gas diffusion layer. Is also called). This separator also functions as a current collector for the generated electricity.

  As an example of the fuel cell, the reaction gas channel formed in the separator is separated into a gas supply channel and a gas discharge channel, and the reaction gas supplied through the gas supply channel is the gas described above. A fuel cell having a structure in which gas is discharged from a gas discharge channel through a diffusion layer or a catalyst electrode layer is known (see Patent Document 1).

JP 2004-079457 A JP 2006-127770 A

  However, in the gas flow path having a structure in which the gas supply flow path and the gas discharge flow path are separated from each other, the downstream end of the gas supply flow path is in a closed state. Is not drained but stays at the downstream end (blocked portion), and there is a problem that flooding is likely to occur in the fuel cell. In general, water is generated by the electrochemical reaction on the cathode side. Therefore, if the gas flow path on the cathode side has the above-described separation structure, water tends to stay in the closed portion. Further, since the water generated on the cathode side also moves to the anode side through the electrolyte membrane, even when the gas flow path on the anode side has the above-described separation structure, water tends to stay in the closed portion.

  Then, an object of this invention is to provide the technique which suppresses that water retains in the downstream end part (blocking part) of the flow path for gas supply.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A fuel cell comprising a catalyst electrode layer, a gas diffusion layer, and a gas flow path forming portion on both surfaces of the electrolyte membrane,
At least one of the gas flow path forming portions is closed on the side in contact with the gas diffusion layer along the surface of the gas diffusion layer, and the gas supply flow path whose downstream end is blocked and its upstream end. Gas flow paths having separate structures in which the gas discharge flow paths are alternately arranged across the blocking portions are formed,
In the fuel cell, the temperature of the downstream end portion of the gas supply flow path is set so that the gas supply flow path portion upstream of the downstream end portion and the discharge flow path adjacent to the downstream end portion of the gas supply flow path. A fuel cell having a temperature difference generating structure that is higher than the temperature of the portion.
According to this fuel cell, by having the temperature difference generating structure, an increase in pressure loss in the entire gas flow path is suppressed, and the gas discharge flow path portion adjacent to the downstream end portion of the gas supply flow path is provided. Only the differential pressure of the gas at the downstream end portion of the gas supply flow path with respect to the gas pressure is expanded, and water staying at the downstream end portion of the gas supply flow path is discharged through the gas diffusion layer and the catalyst electrode layer. It is pushed out to the flow path side. As a result, it is possible to discharge water accumulated at the downstream end of the gas supply channel.

[Application Example 2]
A fuel cell according to Application Example 1,
In the temperature difference generating structure, the temperature of the downstream end portion of the gas supply flow channel is set to be adjacent to the gas supply flow channel portion upstream of the downstream end portion and the downstream end portion of the gas supply flow channel. A fuel cell comprising a high temperature structure that is higher than the temperature of the flow path portion.
In this way, the high temperature structure suppresses an increase in pressure loss in the entire gas flow path, while expanding only the gas volume at the downstream end portion of the gas supply flow path, By expanding only the differential pressure between the gas in the gas discharge flow path adjacent to the downstream end portion, water remaining in the downstream end portion of the gas supply flow path is removed from the gas diffusion layer and the catalyst electrode layer. Through the gas discharge channel. As a result, it is possible to discharge water accumulated at the downstream end of the gas supply channel.

[Application Example 3]
A fuel cell according to Application Example 2,
The high temperature structure is configured by increasing the amount of catalyst in a region corresponding to the downstream end of the gas supply flow path in the catalyst electrode layer more than other regions. battery.
In this way, the electrochemical reaction in the downstream end portion of the gas supply channel occurs more actively than in other portions, and a large amount of reaction heat is generated, so the downstream end of the gas supply channel This temperature can be higher than the temperatures of the gas supply channel portion upstream of the downstream end and the discharge channel portion adjacent to the downstream end of the gas supply channel.

[Application Example 4]
A fuel cell according to Application Example 2,
The fuel cell according to claim 1, wherein the high temperature structure includes a heater for heating at a position corresponding to a downstream end portion of the gas supply channel outside the gas channel forming unit.
In this way, the temperature of the downstream end of the gas supply flow path is determined from the temperature of the gas supply flow path part upstream of the downstream end part and the temperature of the discharge flow path part adjacent to the downstream end part of the gas supply flow path. Can also be hot.

[Application Example 5]
A fuel cell according to Application Example 2,
The high temperature structure is configured by making the electric resistance of the region corresponding to the downstream end of the gas supply flow channel of the gas flow channel forming portion larger than the electric resistance of the region corresponding to the other part. A fuel cell.
If it does in this way, the heat loss which generate | occur | produces by the electrical resistance of the area | region corresponding to the downstream end part of the flow path for gas supply among gas flow path formation parts generate | occur | produces by the electrical resistance of the area | region corresponding to another part. Since the heat loss can be increased, the temperature of the downstream end portion of the gas supply flow path can be increased adjacent to the gas supply flow path portion upstream of the downstream end portion and the downstream end portion of the gas supply flow path. The temperature can be higher than the temperature of the flow path portion.

[Application Example 6]
A fuel cell according to Application Example 2,
The high temperature structure is configured by making the electric resistance of a region corresponding to the downstream end portion of the gas supply channel in the gas diffusion layer larger than the electric resistance of a region corresponding to another portion. The fuel cell characterized by the above-mentioned.
In this way, the heat loss generated by the electrical resistance in the region corresponding to the downstream end of the gas supply flow path in the gas diffusion layer is caused by the electrical resistance in the region corresponding to the other part. Therefore, the temperature of the downstream end of the gas supply flow path can be made larger than that of the gas supply flow path portion upstream of the downstream end and the discharge flow path adjacent to the downstream end of the gas supply flow path. The temperature can be higher than the temperature of the portion.

[Application Example 7]
A fuel cell according to Application Example 1 or Application Example 2,
In the temperature difference generating structure, the temperature at the downstream end of the gas supply channel is lower than the temperature of the gas supply channel and the discharge channel adjacent to the downstream end of the gas supply channel. A fuel cell comprising a low-temperature suppression structure that prevents the temperature from becoming low.
In this manner, the structure for reducing the temperature of the gas discharge channel portion adjacent to the downstream end of the gas supply channel is suppressed while suppressing the increase in pressure loss in the entire gas channel by the low temperature suppression structure. By reducing the size, the gas volume at the downstream end of the gas supply flow path is increased, and the gas discharge flow path portion adjacent to the downstream end portion of the gas supply flow path is downstream of the gas supply flow path. Only the differential pressure of the gas at the end can be increased, and the water staying at the downstream end of the gas supply channel can be pushed out to the gas discharge channel through the gas diffusion layer and the catalyst electrode layer. As a result, it is possible to discharge water accumulated at the downstream end of the gas supply channel.

[Application Example 8]
A fuel cell according to Application Example 7,
A refrigerant flow path forming portion in which a refrigerant flow path is formed on a side opposite to the gas flow path forming side of the gas flow path forming portion;
The low temperature suppression structure is constituted by the refrigerant flow path formed so that the refrigerant flows in order from the upstream side to the downstream end portion of the gas supply flow path.
In this way, the temperature of the gas supply flow path portion upstream from the downstream end of the gas supply flow path and the temperature of the gas discharge flow path portion adjacent to the downstream end of the gas supply flow path are determined. It is possible to make it cooler than the downstream end of the path.

[Application Example 9]
A fuel cell according to Application Example 7,
A refrigerant flow path forming portion in which a refrigerant flow path is formed on a side opposite to the gas flow path forming side of the gas flow path forming portion;
The low temperature suppression structure is constituted by the refrigerant channel formed so that the refrigerant does not flow to the downstream end portion of the gas supply channel.

[Application Example 10]
A fuel cell according to Application Example 7,
The fuel cell according to claim 1, wherein the low temperature suppression structure includes a heat insulating material provided at a downstream end portion of the gas supply channel.
In this way, since heat radiation from the downstream end of the gas supply channel can be suppressed, the gas supply channel portion and the gas supply channel upstream from the downstream end of the gas supply channel. It is possible to make the temperature of the gas discharge channel portion adjacent to the downstream end portion lower than the downstream end portion of the gas supply channel.

[Application Example 11]
The fuel cell according to any one of Application Example 1 to Application Example 10,
The gas flow path forming part is composed of a member containing carbon and resin,
The temperature difference generating structure includes a structure in which the resin ratio in the downstream end portion of the gas supply flow path is made higher in the gas flow path forming portion than in other portions.
In this case, since the thermal conductivity of the downstream end of the gas supply flow path is lowered, the temperature of the downstream end of the gas supply flow path and the gas supply flow path portion upstream of the downstream end and the gas are reduced. It is possible to make the temperature easy to be higher than the temperature of the gas discharge channel portion adjacent to the downstream end portion of the supply channel.

[Application Example 12]
The fuel cell according to any one of Application Example 1 to Application Example 10,
The temperature difference generating structure includes a structure in which a hollow portion is formed in the gas flow path forming portion or the gas diffusion layer so as to cover a downstream end portion of the gas supply flow path.
In this way, since the hollow part provided in the gas flow path forming part or the gas diffusion layer works to block heat dissipation, the temperature of the downstream end of the gas supply flow path is higher than the downstream end. It is possible to make the temperature more likely to be higher than the temperatures of the supply flow path portion and the gas discharge flow path portion adjacent to the downstream end of the gas supply flow path.

It is a cross-sectional schematic diagram showing schematic structure of the fuel cell which comprises the fuel cell to which this invention is applied. It is explanatory drawing shown about the basic concept of embodiment of this invention. It is the schematic structure figure which looked at the anode side catalyst electrode layer 14A which shows the 1st example of the 1st method from the anode side separator 20A side. It is the schematic structure figure which looked at the opposite side to the gas flow path 30 of the anode side separator 20A which shows 2nd Example of a 1st method. It is the schematic structure figure which looked at the gas diffusion layer 16A on the anode side which shows the 3rd example of the 1st technique from the separator 20A side on the anode side. It is the schematic structure figure which looked at anode separator 20A which shows the 4th example of the 1st technique from the outside. FIG. 6 is a schematic structural diagram of a refrigerant flow path forming portion 60A provided outside an anode-side separator 20A showing a first embodiment of the second technique. FIG. 6 is a schematic structural diagram of a refrigerant flow path forming portion 60Aa provided outside an anode separator 20A showing a second embodiment of the second technique. It is the schematic structure figure which looked at the gas channel 30 side of separator 20Aa on the anode side which shows the 3rd example of the 2nd technique. It is a schematic block diagram which shows a part by the side of the gas flow path 30 of separator 20Ab by the side of the anode which shows 1st Example of a 3rd method. It is a schematic block diagram which shows a part by the side of the gas flow path 30 of separator 20Ac by the side of the anode which shows 2nd Example of the 3rd method. It is a schematic block diagram which shows a part of anode side gas diffusion layer 16Ac which shows 3rd Example of the 3rd method.

A. Overview of fuel cell configuration:
FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a fuel cell constituting a fuel cell to which the present invention is applied. The fuel cell 100 includes a membrane electrode assembly 10, and an anode-side separator 20A and a cathode-side separator 20C that sandwich the membrane electrode assembly 10 from both sides. The membrane electrode assembly 10 is adjacent to the electrolyte layer 12, the anode-side catalyst electrode layer 14A and the cathode-side catalyst electrode layer 14C formed on each surface of the electrolyte layer 12, and the catalyst electrode layers. The anode-side gas diffusion layer 16A and the cathode-side gas diffusion layer 16C are provided. The catalyst electrode layer and the gas diffusion layer are collectively referred to as a gas diffusion electrode or a gas diffusion electrode layer.

  The electrolyte layer 12 is a proton conductive ion exchange membrane formed of a solid polymer material, for example, a fluorine-based resin, and exhibits good proton conductivity in a wet state. For example, a Nafion membrane (manufactured by DuPont) is used as the electrolyte layer 12.

  The anode-side catalyst electrode layer 14A and the cathode-side catalyst electrode layer 14C include a catalyst metal that promotes an electrochemical reaction, an electrolyte having proton conductivity, and carbon particles having electron conductivity. As the catalyst metal, for example, platinum (Pt) or an alloy composed of Pt and another metal (for example, a Pt alloy in which cobalt or nickel is mixed) can be used. As the electrolyte, a fluorine-based resin that conducts hydrated protons via a sulfonic acid group, for example, a Nafion solution, is used as in the electrolyte layer 12. The catalyst metal is supported on carbon particles, and in each catalyst electrode layer, carbon particles (catalyst particles) supporting the catalyst metal and an electrolyte are mixed. Carbon particles for supporting a catalytic metal (hereinafter referred to as “supporting carbon particles”) are generally made of carbon particles (carbon powder) that are commercially available, and have their water repellency improved by heat treatment. Hydrated carbon particles are used.

  The gas diffusion layers 16A and 16C can be made of a gas permeable conductive member, for example, a carbon porous body such as carbon cloth or carbon paper, or a metal porous body such as a metal mesh or foam metal. .

The separators 20A and 20C can be formed of a gas-impermeable conductive member, for example, dense carbon that is compressed by gas and impermeable to gas, or a press-molded metal plate. On the surfaces of the separators 20A and 20C on the gas diffusion layers 16A and 16C side, hydrogen (H ₂ ) as a reaction gas supplied to the fuel cell 100 or oxygen (more specifically, air) as an oxidant gas. ) Is formed. That is, a gas flow path 30 through which a reaction gas used for an electrochemical reaction passes is formed between the gas diffusion layers 16A and 16C and the separators 20A and 20C. Specifically, a gas supply flow path 30i communicating with a gas supply manifold (not shown) and a gas discharge flow path 30o communicating with a gas discharge manifold for discharging unreacted gas flowing out from the fuel cell are formed. . The gas supply channel 30i and the gas discharge channel 30o are separated from each other. That is, the downstream end of the gas supply channel 30i and the upstream end of the gas discharge channel 30o are closed. The gas supply flow path 30i and the gas discharge flow path 30o are alternately arranged with the gas discharge flow path 30o sandwiching the downstream end portion (blocking portion) of the gas supply flow path 30i. The separators 20A and 20C correspond to the gas flow path forming part in the present invention.

  A sealing member (not shown) is provided on the outer peripheral portion of the fuel cell 100 to ensure the gas sealing property of the reaction gas. Note that the normal fuel cell has a stack structure in which a plurality of fuel cells 100 are stacked, and a reaction gas (fuel gas or A plurality of manifolds (not shown) through which the oxidizing gas) and the refrigerant circulate are provided. The fuel gas flowing through the fuel gas supply manifold among the plurality of manifolds is distributed to each fuel cell 100 and passes through the fuel gas flow path of each fuel cell while being subjected to an electrochemical reaction. , Gather in the fuel gas discharge manifold. Similarly, the oxidant gas flowing through the oxidant gas supply manifold is distributed to each fuel cell 100 and passes through the gas channel for the oxidant gas of each fuel cell while being subjected to an electrochemical reaction. Collect in the manifold.

  In addition, although illustration is abbreviate | omitted, in order to adjust the internal temperature of a stack structure, the refrigerant flow path formation part in which the refrigerant flow path through which a refrigerant | coolant passes was formed between each fuel cell. The refrigerant flow path forming portion is provided between the separators 20A and 20C provided in one fuel battery cell and the separators 20C and 20A of the other fuel battery cell provided adjacent to the fuel battery cell between adjacent fuel battery cells. What is necessary is just to provide.

  In the fuel cell 100, hydrogen as the fuel gas supplied to the gas supply passage 30i of the anode-side separator 20A is supplied to the catalyst electrode layer 14A via the gas diffusion layer 16A and is generated by the catalyst electrode layer 14A. After contributing to the electrochemical reaction, the gas is discharged through the gas discharge passage 30o. Similarly, oxygen as an oxidizing gas supplied to the gas supply flow path 30i of the cathode-side separator 20C is also supplied to the catalyst electrode layer 14C via the gas diffusion layer 16C and undergoes an electrochemical reaction by the catalyst electrode layer 14C. After the contribution, the gas is discharged through the gas discharge channel 30o. In the fuel cell 100, as described above, the reaction gas supplied to the anode side and the cathode side is subjected to an electrochemical reaction, and as a result, power is generated and water is generated as a byproduct.

B. Basic concept of the embodiment:
FIG. 2 is an explanatory diagram showing the basic concept of the embodiment of the present invention. The figure shows an enlarged schematic cross section of the downstream end portion (blocking portion) of the gas supply flow passage 30i and the portion of the gas discharge flow passage 30o adjacent thereto.

  The basic concept of the embodiment of the present invention is to compare the pressure P1 of the reaction gas in the downstream end portion of the gas supply flow path 30i with the pressure P2 of the reaction gas in the adjacent gas discharge flow path 30o, The differential pressure is generated as P1 >> P2. Then, by generating the differential pressure in this way, the water staying in the downstream end portion of the gas supply flow path 30i becomes the gas diffusion electrode layer (the gas diffusion layer 16A (16C) and the catalyst electrode layer 14A (14C)). ) Through the gas discharge passage 30o, drainage becomes possible, and flooding is suppressed.

As a technique for generating the differential pressure as described above, a temperature difference generating structure is used in order to generate a temperature difference between the downstream end portion of the gas supply flow path 30i and the gas discharge flow path 30o adjacent thereto. It is conceivable to provide There are three main methods for realizing the temperature difference generating structure.
[1] First method: a method having a structure (high temperature structure) for heating only the downstream end portion of the gas supply channel 30i.
[2] Second method: a method having a structure (cooling suppression structure) in which only the downstream end portion of the gas supply flow channel 30i is not cooled from the other flow channel portions.
[3] Third method: In addition to the first method, the second method, or the first method and the second method, heat escapes from the wall surface of the downstream end portion of the gas supply channel 30i. A technique that has a structure that blocks heat so that there is no such thing.
Hereinafter, the first method embodiment, the second method embodiment, and the third method embodiment will be described in this order.

C. Embodiment of the first technique:
As described above, the first technique has a structure (high temperature structure) that heats only the downstream end portion of the gas supply channel 30i, so that water stays in the downstream end portion of the gas supply channel 30i. Are to be discharged. As examples, the following four examples will be described.

C1. First embodiment of the first technique:
FIG. 3 is a schematic structural view of the anode-side catalyst electrode layer 14A as viewed from the anode-side separator 20A side, showing the first embodiment of the first technique. A substantially rectangular area indicated by dot hatching in the figure indicates the area of the catalyst electrode layer 14A. Also, the broken lines indicate the communication passage 30si connected to the fuel gas supply manifold 40i, the gas supply passage 30i connected to the communication passage 30si, the communication passage 30so connected to the gas discharge manifold 40o, and A gas discharge passage 30o connected to the communication passage 30so is shown.

  In the present embodiment, as shown in the figure, the catalyst is increased only in the region 14 Astp corresponding to the downstream end portion of the gas supply channel 30 i of the catalyst electrode layer 14 A on the anode side. The region 14Atp can be formed, for example, by applying a catalyst ink having a high catalyst concentration, unlike the catalyst ink applied to other regions only in the region of 14AStp.

  As described above, if only the region 14Astp corresponding to the downstream end portion of the gas supply channel 30i is configured to increase the catalyst, the catalytic reaction in the region 14Astp increases compared to the other regions, and the region 14Astp It becomes possible to raise the temperature of the downstream end part of the corresponding gas supply flow path 30i as compared with other parts. As a result, the gas volume of the portion can be expanded to increase the gas pressure, and the differential pressure with respect to the gas pressure in the gas discharge passage 30o adjacent to the downstream end portion of the gas supply passage 30i can be obtained. Can be generated. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be pushed out to the gas discharge channel 30o through the gas diffusion electrode layer and discharged.

  The above embodiment has been described by taking the anode side as an example, but the same applies to the cathode side.

C2. Second embodiment of the first technique:
FIG. 4 is a schematic structural view of the anode separator 20A showing the second embodiment of the first method when viewed from the side opposite to the gas flow path 30. As shown in FIG. The broken lines in the figure indicate the communication passage 30si and the communication passage 30si connected to the gas supply manifold 40i of the fuel gas formed on the side in contact with the gas diffusion layer 16A of the separator 20A, as described in FIG. The gas supply flow path 30i connected to the gas discharge manifold 40o and the gas discharge flow path 30o connected to the communication path 30so are shown.

  In the present embodiment, as shown in the figure, a heater 50h is provided in the outer portion of the separator 20A corresponding to the anode-side gas supply channel 30i. The power supply line to the heater 50h is not shown.

  As described above, if the heater 50h is provided in the outer portion of the separator 20A corresponding to the gas supply flow path 30i, the temperature of the downstream end portion of the gas supply flow path 30i is increased as compared with other portions. It becomes possible to make it. As a result, the gas volume of the portion can be expanded to increase the gas pressure, and the differential pressure with respect to the gas pressure in the gas discharge passage 30o adjacent to the downstream end portion of the gas supply passage 30i can be obtained. Can be generated. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be pushed out to the gas discharge channel 30o through the gas diffusion electrode layer and discharged.

  In addition, although the said Example demonstrated the anode side as an example, the cathode side is also the same.

C3. Third embodiment of the first technique:
FIG. 5 is a schematic structural view of an anode-side gas diffusion layer 16A as viewed from the anode-side separator 20A side, showing a third embodiment of the first technique. The substantially rectangular area shown by the cross-hatching in the figure shows the area of the gas diffusion layer 16A. Also, the broken lines indicate the communication passage 30si connected to the fuel gas supply manifold 40i, the gas supply passage 30i connected to the communication passage 30si, the communication passage 30so connected to the gas discharge manifold 40o, and A gas discharge passage 30o connected to the communication passage 30so is shown.

  In the present embodiment, as shown in the figure, the electric resistance of the region 16Astp corresponding to the downstream end portion of the gas supply channel 30i of the gas diffusion layer 16A on the anode side is configured to be higher than that of other regions. Has been. For example, when the carbon porous body is used as the gas diffusion layer, the region 16Astp can be formed by using a carbon porous body having a higher electric resistance than other regions.

  As described above, if only the region 16Astp corresponding to the downstream end portion of the gas supply flow path 30i is configured to increase the electrical resistance, the heat loss in the region 16Astp increases and heat is generated, and the region 16Astp corresponds to the region 16Astp. It becomes possible to raise the temperature of the downstream end portion of the gas supply flow path 30i as compared with other portions. As a result, the gas volume of the portion can be expanded to increase the gas pressure, and the differential pressure with respect to the gas pressure in the gas discharge passage 30o adjacent to the downstream end portion of the gas supply passage 30i can be obtained. Can be generated. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be pushed out to the gas discharge channel 30o through the gas diffusion electrode layer and discharged.

  The above embodiment has been described by taking the anode side as an example, but the same applies to the cathode side.

C4. Fourth embodiment of the first technique:
FIG. 6 is a schematic structural view of an anode-side separator 20A as viewed from the outside, showing a fourth embodiment of the first technique. The broken lines in the figure indicate the communication passage 30si and the communication passage 30si connected to the gas supply manifold 40i of the fuel gas formed on the side in contact with the gas diffusion layer 16A of the separator 20A, as described in FIG. The gas supply flow path 30i connected to the gas discharge manifold 40o and the gas discharge flow path 30o connected to the communication path 30so are shown.

  In the present embodiment, as shown in the drawing, the electric resistance of the region 20Astp corresponding to the downstream end portion of the gas supply channel 30i of the separator 20A is configured to be higher than that of other regions. For example, when the dense carbon is used as the gas diffusion layer as the separator 20A, the region 20Astp can be formed by using dense carbon having a higher electric resistance than other regions.

  As described above, if only the region 20Astp corresponding to the downstream end portion of the gas supply flow path 30i of the separator 20A is configured to increase the electrical resistance, heat loss in the region 20Astp increases and heat is generated, and the region 20Astp It is possible to raise the temperature of the downstream end portion of the gas supply flow path 30i corresponding to the above in comparison with other portions. As a result, the gas volume of the portion can be expanded to increase the gas pressure, and the differential pressure with respect to the gas pressure in the gas discharge passage 30o adjacent to the downstream end portion of the gas supply passage 30i can be obtained. Can be generated. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be pushed out to the gas discharge channel 30o through the gas diffusion electrode layer and discharged.

The above embodiment has been described by taking the anode side as an example, but the same applies to the cathode side.
D. Second method embodiment:
As described above, the second technique has a structure (cooling suppression structure) in which only the downstream end portion of the gas supply flow path 30i is not cooled from the other flow path portions. The water staying in the downstream end portion is discharged. The following three examples are shown as examples.

D1. First embodiment of the second method:
FIG. 7 is a schematic structural diagram of a refrigerant flow path forming portion 60A provided outside the anode-side separator 20A showing the first embodiment of the second technique. For the refrigerant flow path forming portion 60A, for example, dense carbon or a metal plate is used as in the separator 20A. The broken lines in the figure indicate the communication passage 30si and the communication passage 30si connected to the gas supply manifold 40i of the fuel gas formed on the side in contact with the gas diffusion layer 16A of the separator 20A, as described in FIG. The gas supply flow path 30i connected to the gas discharge manifold 40o and the gas discharge flow path 30o connected to the communication path 30so are shown.

  In the refrigerant flow path forming portion 60A, a refrigerant is provided so as to cover the gas flow path 30 (the gas supply flow path 30i, the gas discharge flow path 30o, the communication paths 30si, 30so) of the separator 20A and the membrane electrode assembly 10. A flow path portion 80 is formed. The refrigerant flow path 80 is connected to the refrigerant supply manifold 70i and the refrigerant discharge manifold 70o.

  A plurality of flow path walls 80 w and 80 stpg are formed in the refrigerant flow path portion 80. The flow path wall 80w is formed so that the refrigerant supplied from the refrigerant supply manifold 70i flows linearly and cleanly toward the refrigerant discharge manifold 70o. On the other hand, the plurality of flow path walls 80stp are formed so as to cover the downstream end portion of the gas supply flow path 30i so that the refrigerant does not flow in a region corresponding to the downstream end portion of the gas supply flow path 30i. .

  As described above, the plurality of flow path walls 80stp are formed so as to cover the downstream end portion of the gas supply flow path 30i so that the refrigerant does not flow in the region corresponding to the downstream end portion of the gas supply flow path 30i. As a result, it is possible to suppress the temperature of the downstream end portion of the gas supply flow path 30i from lowering than the other portions. As a result, the pressure of the gas at that portion can be made higher than the pressure of the gas in the gas discharge channel 30o adjacent to the downstream end portion of the gas supply channel 30i, thereby generating a differential pressure. Become. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be pushed out to the gas discharge channel 30o through the gas diffusion electrode layer and discharged.

  In addition, although the said Example demonstrated the anode side as an example, the cathode side is also the same.

D2. Second embodiment of the second technique:
FIG. 8 is a schematic structural diagram of a refrigerant flow path forming portion 60Aa provided outside the anode-side separator 20A showing a second embodiment of the second technique. As in the first embodiment, for example, dense carbon or a metal plate is used for the refrigerant flow path forming portion 60Aa. The broken lines in the figure indicate the communication passage 30si and the communication passage 30si connected to the gas supply manifold 40i of the fuel gas formed on the side in contact with the gas diffusion layer 16A of the separator 20A, as described in FIG. The gas supply flow path 30i connected to the gas discharge manifold 40o and the gas discharge flow path 30o connected to the communication path 30so are shown.

  The refrigerant flow path forming portion 60Aa covers the gas flow path 30 (gas supply flow path 30i, gas discharge flow path 30o, communication paths 30si, 30so) of the separator 20A and the membrane electrode assembly 10 so as to cover the refrigerant flow path forming portion 60Aa. A flow path portion 80 is formed. The refrigerant flow path 80 is connected to the refrigerant supply manifold 70i and the refrigerant discharge manifold 70o.

  A plurality of flow path walls 80 w are formed in the refrigerant flow path portion 80. The flow path wall 80w is formed such that the refrigerant supplied from the refrigerant supply manifold 70i flows linearly toward the refrigerant discharge manifold 70o.

  As described above, the flow path wall 80w is formed so that the refrigerant supplied from the refrigerant supply manifold 70i flows linearly toward the refrigerant discharge manifold 70o, so the downstream end portion of the gas supply flow path 30i. The refrigerant flows in the region corresponding to the point immediately before the refrigerant is discharged from the refrigerant discharge manifold 70o. In this case, the refrigerant passing through the downstream end portion of the gas supply channel 30i is heated by absorbing the reaction heat generated by the power generation when passing through the upstream portion. For this reason, it becomes possible to suppress that the temperature of the downstream end part of the flow path 30i for gas supply falls compared with another part. As a result, the pressure of the gas at that portion can be made higher than the pressure of the gas in the gas discharge channel 30o adjacent to the downstream end portion of the gas supply channel 30i, thereby generating a differential pressure. Become. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be pushed out to the gas discharge channel 30o through the gas diffusion electrode layer and discharged.

  In addition, although the said Example demonstrated the anode side as an example, the cathode side is also the same.

D3. Third embodiment of the second technique:
FIG. 9 is a schematic structural view of the anode-side separator 20 </ b> Aa as viewed from the gas flow path 30 side according to the third embodiment of the second method. This separator 20Aa is provided with a heat insulating material on the wall surface 30ij at the downstream end portion of the gas supply channel 30i. As the heat insulating material, a resin material having low thermal conductivity can be used.

  As described above, in the case where a heat insulating material is provided on the wall surface 30ij of the downstream end portion of the gas supply flow path 30i, since the heat radiation of this portion can be blocked, the downstream end of the gas supply flow path 30i It becomes possible to suppress that the temperature of a part falls compared with another part. As a result, the pressure of the gas at that portion can be made higher than the pressure of the gas in the gas discharge channel 30o adjacent to the downstream end portion of the gas supply channel 30i, thereby generating a differential pressure. Become. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be pushed out to the gas discharge channel 30o through the gas diffusion electrode layer and discharged.

  In addition, although the said Example demonstrated the anode side as an example, the cathode side is also the same.

E. Embodiment of the third technique:
As described above, in the third method, in addition to the first method, the second method, or the first method and the second method, the wall surface of the downstream end portion of the gas supply flow path 30i is used. By having a structure that blocks heat so that heat does not escape, water staying in the downstream end portion of the gas supply channel 30i is discharged. The following three examples are shown as examples.

E1. First embodiment of the third technique:
FIG. 10 is a schematic configuration diagram showing a part of the anode-side separator 20Ab on the gas flow path 30 side showing the first embodiment of the third technique. This separator 20Ab uses a synthetic member of dense carbon and resin. And about the downstream end part 30ir of the flow path 30i for gas supply, it comprises using the synthetic | combination member with a high ratio of resin compared with another part.

  As described above, by setting the ratio of the resin in the other end portion 30ir of the gas supply channel 30i to that of the other portions, the thermal conductivity of this portion can be reduced. When combined with the first method, the temperature heated by the first method is suppressed from decreasing, and the temperature of the downstream end portion of the gas supply channel 30i is increased compared to the other portions. It becomes possible. As a result, the gas volume of the portion can be expanded to increase the gas pressure, and the differential pressure with respect to the gas pressure in the gas discharge passage 30o adjacent to the downstream end portion of the gas supply passage 30i can be obtained. Can be generated. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be pushed out to the gas discharge channel 30o through the gas diffusion electrode layer and discharged.

  When combined with the second method, the second method can more effectively suppress the temperature drop at the downstream end portion of the gas supply channel 30i. As a result, the pressure of the gas in that portion is made higher than the pressure of the gas in the gas discharge flow channel 30o adjacent to the downstream end portion of the gas supply flow channel 30i, thereby generating a differential pressure more effectively. It becomes possible. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be more effectively pushed and discharged to the gas discharge channel 30o through the gas diffusion electrode layer.

  Furthermore, when combining the first to third methods, the downstream of the gas supply flow path 30i due to both the effect of the combination with the first method and the effect of the combination with the second method. A differential pressure between the gas pressure at the end portion and the gas pressure in the gas discharge channel 30o adjacent to the downstream end portion of the gas supply channel 30i can be generated more effectively. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be pushed out to the gas discharge channel 30o through the gas diffusion electrode layer and discharged more effectively.

E2. Second embodiment of the third technique:
FIG. 11 is a schematic configuration diagram showing a part on the gas flow path 30 side of the anode-side separator 20Ac showing the second embodiment of the third technique. This separator 20Ac has a configuration in which a hollow portion 30m is provided in the peripheral portion of the downstream end of the gas supply channel 30i.

  As described above, by providing the hollow portion 30m around the downstream end of the gas supply channel 30i, the thermal conductivity of this portion can be reduced. When combined with the first method, the temperature heated by the first method is suppressed from decreasing, and the temperature of the downstream end portion of the gas supply channel 30i is increased compared to the other portions. It becomes possible. As a result, the gas volume of the portion can be expanded to increase the gas pressure, and the differential pressure with respect to the gas pressure in the gas discharge passage 30o adjacent to the downstream end portion of the gas supply passage 30i can be obtained. Can be generated. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be pushed out to the gas discharge channel 30o through the gas diffusion electrode layer and discharged.

  When combined with the second method, the second method can more effectively suppress the temperature drop at the downstream end portion of the gas supply channel 30i. As a result, the pressure of the gas in that portion is made higher than the pressure of the gas in the gas discharge flow channel 30o adjacent to the downstream end portion of the gas supply flow channel 30i, thereby generating a differential pressure more effectively. It becomes possible. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be more effectively pushed and discharged to the gas discharge channel 30o through the gas diffusion electrode layer.

  Furthermore, when combining the first to third methods, the downstream of the gas supply flow path 30i due to both the effect of the combination with the first method and the effect of the combination with the second method. A differential pressure between the gas pressure at the end portion and the gas pressure in the gas discharge channel 30o adjacent to the downstream end portion of the gas supply channel 30i can be generated more effectively. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be pushed out to the gas discharge channel 30o through the gas diffusion electrode layer and discharged more effectively.

E3. Third embodiment of the third technique:
FIG. 12 is a schematic configuration diagram showing a part of the gas diffusion layer 16Ac on the anode side showing a third embodiment of the third technique. The broken lines in the figure show a part of the gas supply flow path 30i and the gas discharge flow path 30o formed on the side of the separator 20A in contact with the gas diffusion layer 16A. This gas diffusion layer 16Ac has a configuration in which a hollow portion 16Acm is provided in a peripheral portion of a region corresponding to the downstream end portion of the gas supply channel 30i.

  As described above, by providing the hollow portion 16Acm in the peripheral portion of the region corresponding to the downstream end portion of the gas supply channel 30i of the gas diffusion layer 16Ac, the thermal conductivity of the downstream end portion of the gas supply channel 30i is provided. Can be reduced. When combined with the first method, the temperature heated by the first method is suppressed from decreasing, and the temperature of the downstream end portion of the gas supply channel 30i is increased compared to the other portions. It becomes possible. As a result, the gas volume of the portion can be expanded to increase the gas pressure, and the differential pressure with respect to the gas pressure in the gas discharge passage 30o adjacent to the downstream end portion of the gas supply passage 30i can be obtained. Can be generated. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be pushed out to the gas discharge channel 30o through the gas diffusion electrode layer and discharged.

  When combined with the second method, the second method can more effectively suppress the temperature drop at the downstream end portion of the gas supply channel 30i. As a result, the pressure of the gas in that portion is made higher than the pressure of the gas in the gas discharge flow channel 30o adjacent to the downstream end portion of the gas supply flow channel 30i, thereby generating a differential pressure more effectively. It becomes possible. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be more effectively pushed and discharged to the gas discharge channel 30o through the gas diffusion electrode layer.

  Furthermore, when combining the first to third methods, the downstream of the gas supply flow path 30i due to both the effect of the combination with the first method and the effect of the combination with the second method. A differential pressure between the gas pressure at the end portion and the gas pressure in the gas discharge channel 30o adjacent to the downstream end portion of the gas supply channel 30i can be generated more effectively. As a result, the water staying in the downstream end portion of the gas supply channel 30i can be pushed out to the gas discharge channel 30o through the gas diffusion electrode layer and discharged more effectively.

F. Variations:
In addition, elements other than the elements claimed in the independent claims among the constituent elements in each of the above embodiments are additional elements and can be omitted as appropriate. The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the scope of the invention.

  For example, in each of the above-described embodiments, the anode-side fuel gas flow path and the cathode-side gas flow path are described as an example in which the gas supply flow path and the gas discharge flow path are separated. However, the present invention is not limited to this, and one of the gas flow paths may be the same as the conventional one, and the gas supply flow path and the gas discharge flow path may be common.

DESCRIPTION OF SYMBOLS 10 ... Membrane electrode assembly 12 ... Electrolyte layer 14 Astp ... Area | region 14ASTp ... Area | region 14A ... Catalyst electrode layer 14C ... Catalyst electrode layer 16Atp ... Area | region 16Acm ... Hollow part 16A ... Gas diffusion layer 16C ... Gas diffusion layer 16Ac ... Gas diffusion layer 20 ... Separator 20 Astp ... Area 20A ... Separator 20C ... Separator 20Aa ... Separator 20Ab ... Separator 20Ac ... Separator 30 ... Gas channel 30i ... Gas supply channel 30m ... Hollow part 30o ... Gas exhaust channel 30ij ... Wall surface 30ir ... Other end Portion 30si ... Communication passage 30so ... Communication passage 40i ... Gas supply manifold 40o ... Gas discharge manifold 50h ... Heater 60A ... Refrigerant flow passage formation portion 60Aa ... Refrigerant flow passage formation portion 70i ... Refrigerant supply manifold 70o ... Refrigerant discharge manifold 80 ... Nakadachiryuro part 80stp ... the flow path wall 80w ... the channel wall 100 ... fuel cell

Claims (12)

A fuel cell comprising a catalyst electrode layer, a gas diffusion layer, and a gas flow path forming portion on both surfaces of the electrolyte membrane,
At least one of the gas flow path forming portions is closed on the side in contact with the gas diffusion layer along the surface of the gas diffusion layer, and the gas supply flow path whose downstream end is blocked and its upstream end. Gas flow paths having separate structures in which the gas discharge flow paths are alternately arranged across the blocking portions are formed,
In the fuel cell, the temperature of the downstream end portion of the gas supply flow path is set so that the gas supply flow path portion upstream of the downstream end portion and the discharge flow path adjacent to the downstream end portion of the gas supply flow path. A fuel cell having a temperature difference generating structure that is higher than the temperature of the portion. The fuel cell according to claim 1, wherein
In the temperature difference generating structure, the temperature of the downstream end portion of the gas supply flow channel is set to be adjacent to the gas supply flow channel portion upstream of the downstream end portion and the downstream end portion of the gas supply flow channel. A fuel cell comprising a high temperature structure that is higher than the temperature of the flow path portion. The fuel cell according to claim 2, wherein
The high temperature structure is configured by increasing the amount of catalyst in a region corresponding to the downstream end of the gas supply flow path in the catalyst electrode layer more than other regions. battery. The fuel cell according to claim 2, wherein
The fuel cell according to claim 1, wherein the high temperature structure includes a heater for heating at a position corresponding to a downstream end portion of the gas supply channel outside the gas channel forming unit. The fuel cell according to claim 2, wherein
The high temperature structure is configured by making the electric resistance of the region corresponding to the downstream end of the gas supply flow channel of the gas flow channel forming portion larger than the electric resistance of the region corresponding to the other part. A fuel cell. The fuel cell according to claim 2, wherein
The high temperature structure is configured by making the electric resistance of a region corresponding to the downstream end portion of the gas supply channel in the gas diffusion layer larger than the electric resistance of a region corresponding to another portion. The fuel cell characterized by the above-mentioned. The fuel cell according to claim 1 or 2, wherein
In the temperature difference generating structure, the temperature at the downstream end of the gas supply channel is lower than the temperature of the gas supply channel and the discharge channel adjacent to the downstream end of the gas supply channel. A fuel cell comprising a low-temperature suppression structure that prevents the temperature from becoming low. The fuel cell according to claim 7, wherein
A refrigerant flow path forming portion in which a refrigerant flow path is formed on a side opposite to the gas flow path forming side of the gas flow path forming portion;
The low temperature suppression structure is constituted by the refrigerant flow path formed so that the refrigerant flows in order from the upstream side to the downstream end portion of the gas supply flow path. The fuel cell according to claim 7, wherein
A refrigerant flow path forming portion in which a refrigerant flow path is formed on a side opposite to the gas flow path forming side of the gas flow path forming portion;
The low temperature suppression structure is constituted by the refrigerant channel formed so that the refrigerant does not flow to the downstream end portion of the gas supply channel. The fuel cell according to claim 7, wherein
The fuel cell according to claim 1, wherein the low temperature suppression structure includes a heat insulating material provided at a downstream end portion of the gas supply channel. A fuel cell according to any one of claims 1 to 10, wherein
The gas flow path forming part is composed of a member containing carbon and resin,
The temperature difference generating structure includes a structure in which the resin ratio in the downstream end portion of the gas supply flow path is made higher in the gas flow path forming portion than in other portions. A fuel cell according to any one of claims 1 to 10, wherein
The temperature difference generating structure includes a structure in which a hollow portion is formed in the gas flow path forming portion or the gas diffusion layer so as to cover a downstream end portion of the gas supply flow path.

Images