JP2011018525A - Fuel cell and fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of restraining the deterioration of power generation performance in a fuel cell under operation.SOLUTION: The fuel cell 100 has a membrane-electrode conjugate 5, and an anode plate 20 and a cathode plate 30 for sandwiching the membrane-electrode conjugate 5. An anode flow passage used for hydrogen is arranged between the anode plate 20 and an electrolyte membrane 1, and a cathode flow passage used for oxygen is arranged between the cathode plate 30 and the electrolyte membrane 1. Hydrogen and oxygen are supplied to the anode flow passage and the cathode flow passage so that mutual flow directions may be opposite to each other. A drying acceleration mechanism for accelerating the drying of the anode electrode 2 side electrolyte membrane 1 at an upstream side of the anode flow passage and increasing a moisture content moved from a downstream side of the cathode flow passage to an upstream side of the anode flow passage via the electrolyte membrane 1 is arranged in the fuel cell 100.

Description

  The present invention relates to a fuel cell.

  A fuel cell normally includes a membrane electrode assembly that is a power generator in which electrodes are arranged on both surfaces of an electrolyte membrane. As the electrolyte membrane, a membrane showing good ion conductivity in a wet state is used. For this reason, it is preferable that the inside of the fuel cell be kept in a moderately wet state during operation of the fuel cell. On the other hand, when excessive moisture exists in the fuel cell, so-called flooding occurs, which causes the flow path for the reaction gas (fuel gas and oxidant gas) to be blocked by the moisture. Performance may be significantly reduced. Therefore, it is preferable that the drainage performance of the fuel cell is improved in order to suppress a decrease in the power generation performance of the fuel cell. Until now, various techniques have been proposed for such a demand (the following Patent Document 1 etc.).

  By the way, during the operation of the fuel cell, the reaction gas flows along the electrode surface of the membrane electrode assembly, and the moisture content tends to increase toward the downstream side of the reaction gas on the electrode surface. In particular, the tendency becomes stronger on the cathode electrode side where moisture is generated by the power generation reaction. If the non-uniformity of moisture distribution inside the fuel cell increases, so-called dry-up or the above-mentioned flooding will occur, resulting in the inability to generate power due to drying of the electrolyte membrane in some areas of the fuel cell, resulting in reduced power generation performance of the fuel cell. May be caused.

JP 2009-9724 A JP 2008-1000014 A JP 2008-270019 A

  An object of this invention is to provide the technique which suppresses the fall of the electric power generation performance in the fuel cell in operation.

  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 that generates electricity using an electrochemical reaction between a fuel gas and an oxidant gas, the membrane electrode assembly having a power generation region in which an anode electrode and a cathode electrode are respectively disposed on both surfaces of an electrolyte membrane, and the membrane An anode separator and a cathode separator sandwiching the electrode assembly;
The fuel gas flows between the anode separator and the electrolyte membrane from a first end of the power generation region toward a second end opposite to the first end. And a cathode channel for flowing the oxidant gas from the first end toward the second end between the cathode separator and the electrolyte membrane. And drying the electrolyte membrane on the anode electrode side in the anode upstream side portion closer to the first end portion of the anode flow path, thereby promoting the first of the cathode flow paths. A fuel cell provided with a drying acceleration mechanism for increasing the amount of water that moves through the electrolyte membrane from the cathode downstream portion closer to the end portion to the anode upstream portion.
According to this fuel cell, the moisture in the downstream portion of the cathode can be guided to the upstream portion of the anode by the drying promotion mechanism provided in the upstream portion of the anode, and the occurrence of flooding in the downstream portion of the cathode is suppressed. be able to. Therefore, it is possible to suppress a decrease in power generation performance of the fuel cell during operation. Further, the moisture that has moved to the anode electrode side is guided to the downstream side of the anode channel, and further moves to the upstream side of the cathode channel that tends to dry through the electrolyte membrane. Since the water distribution is improved, the power generation performance of the fuel cell is improved.

[Application Example 2]
In the fuel cell according to Application Example 1, the anode flow path includes an anode flow path groove provided on a surface of the anode separator on the anode electrode side, and the anode flow path between the anode flow path groove and the anode electrode. A fuel gas supply manifold provided at a position outside the first end portion side of the power generation region; and the second end portion of the power generation region. A fuel gas discharge manifold provided at an outer position on the side, wherein the anode flow path groove is connected to the fuel gas supply manifold, and a discharge side connected to the fuel gas discharge manifold The discharge-side anode flow channel has a discharge-side power generation region flow channel extending from the first end side to the second end side in the power generation region. And before Between the supply side anode flow channel and the discharge side anode flow channel, a flow channel partition for separating the supply side anode flow channel and the discharge side anode flow channel is provided. The fuel gas flowing through the supply-side anode flow channel is guided into the gas diffusion layer by the flow channel partition wall, is humidified in the gas diffusion layer, and then flows into the discharge-side anode flow channel. Flowing fuel cell.
According to this fuel cell, it is possible to increase the amount of fuel gas that is induced by the channel groove partition wall and flows into the gas diffusion layer from the supply side anode channel groove in the upstream portion of the anode. Drying of the electrolyte membrane on the anode electrode side can be promoted. In addition, since the discharge-side anode flow channel has the discharge-side power generation region flow channel, drainage performance in the anode flow channel is improved, so that drying of the electrolyte membrane on the anode electrode side is further promoted. Therefore, the occurrence of flooding in the downstream portion of the cathode can be suppressed, and the decrease in power generation performance of the fuel cell during operation can be suppressed.

[Application Example 3]
The fuel cell according to Application Example 2, wherein the supply-side anode channel groove extends in the power generation region from the first end side to the second end side. The supply-side power generation region flow channel and the discharge-side power generation region flow channel are provided so as to run parallel to each other across the flow channel groove partition wall, and the supply-side power generation region flow channel The fuel cell, wherein a channel cross-sectional area of the groove is smaller than a channel cross-sectional area of the discharge-side power generation region channel groove.
According to this fuel cell, the flow rate of the fuel gas in the anode upstream portion can be increased, and the amount of fuel gas flowing from the supply-side anode flow channel into the gas diffusion layer can be increased. Therefore, drying of the electrolyte membrane on the anode electrode side by the fuel gas can be further promoted, generation of flooding in the downstream portion of the cathode can be suppressed, and deterioration in power generation performance of the fuel cell during operation can be suppressed. .

[Application Example 4]
The fuel cell according to Application Example 3, wherein the anode flow path is closer to the upstream side in a range of ½ of the upstream side of the entire range from the first end portion to the second end portion. A fuel cell configured to increase a flow rate of fuel gas.
When the non-humidified oxidant gas is supplied to the fuel cell, the possibility of flooding in the downstream portion of the cathode increases as the operating temperature increases. However, according to this fuel cell, it is possible to suppress the occurrence of flooding even when non-humidified oxidant gas is supplied.

[Application Example 5]
The fuel cell according to Application Example 4, wherein the anode flow path is closer to the upstream side in a range of 3/8 of the upstream side of the entire range from the first end portion to the second end portion. A fuel cell configured to increase a flow rate of fuel gas.
According to this fuel cell, even when non-humidified oxidant gas is supplied, the occurrence of flooding due to the increase in operating temperature is further suppressed.

[Application Example 6]
The fuel cell according to any one of Application Example 1 to Application Example 5, and further, a refrigerant channel that runs alongside the anode channel is provided outside the anode plate, and the anode upstream A heat transfer suppressing member for suppressing heat transfer from the anode flow path to the refrigerant in the refrigerant flow path is disposed on the flow path wall surface on the anode plate side in the refrigerant flow path adjacent to the side portion. A fuel cell.
According to this fuel cell, the cooling effect by the refrigerant in the upstream portion of the anode is suppressed, and the heat transfer suppressing member functions as a drying promotion mechanism. Therefore, drying of the electrolyte membrane in the upstream portion of the anode is promoted, and generation of flooding in the downstream portion of the cathode is suppressed.

[Application Example 7]
The fuel cell according to Application Example 6, wherein the heat transfer suppressing member is provided in a range of ½ of the upstream side of the entire range from the first end to the second end. A fuel cell.
According to this fuel cell, when the non-humidified oxidant gas is supplied by suppressing the cooling effect by the heat transfer suppressing member, in particular, the occurrence of flooding in the downstream portion of the cathode accompanying the increase in operating temperature is suppressed. .

[Application Example 8]
The fuel cell according to Application Example 7, wherein the heat transfer suppressing member is provided in a range of 3/8 on the upstream side of the entire range from the first end to the second end. A fuel cell.
By providing the heat transfer suppressing member in this range, even when non-humidified oxidant gas is supplied to the fuel cell, the occurrence of flooding in the downstream portion of the cathode accompanying the increase in operating temperature is further suppressed.

[Application Example 9]
9. The fuel cell according to any one of Application Examples 1 to 8, wherein the anode electrode has a water diffusion coefficient upstream of the anode flow channel, and a water diffusion coefficient downstream of the anode flow channel. A fuel cell in which two or more regions having different water diffusion coefficients are provided so as to be higher than the diffusion coefficient.
In general, in the anode channel, water is more likely to evaporate as the region has a higher water diffusion coefficient. Therefore, by providing an anode region having a relatively high water diffusion coefficient on the upstream side of the anode channel, this region functions as a drying promotion mechanism. Therefore, the occurrence of flooding on the oxygen downstream side of the cathode is suppressed.

[Application Example 10]
The fuel cell according to Application Example 9, wherein the anode electrode includes a first anode region and a second anode region having a water diffusion coefficient smaller than that of the first anode region. The anode region is provided in a range of 3/8 upstream of the entire range from the first end to the second end, and the second anode region is provided in the first end. The fuel cell is provided so as to include the entire region on the downstream side of the upstream 3/8 range of the entire range from the portion to the second end portion.
By providing the first and second anode regions in the above range, when non-humidified oxidant gas is supplied to the fuel cell, flooding particularly in the downstream portion of the cathode as the operating temperature rises. Occurrence is suppressed.

[Application Example 11]
The fuel cell according to Application Example 10, wherein the first anode region is 1/8 to 3/8 of the upstream side of the entire range from the first end to the second end. The fuel cell is provided in a range, and the second anode region is provided in a region excluding the first anode region.
By providing the first and second anode regions in the above-described range, flooding occurs in the downstream portion of the cathode as the operating temperature rises when non-humidified oxidant gas is supplied to the fuel cell. It is further suppressed.

[Application Example 12]
The fuel cell according to any one of Application Example 9 to Application Example 11, wherein the two or more regions having different water diffusion coefficients are regions having different porosity.
According to this fuel cell, it is possible to easily provide two or more regions having different water diffusion coefficients in the anode electrode.

[Application Example 13]
The fuel cell according to any one of Application Example 9 to Application Example 12, wherein the anode electrode includes an electrolyte and catalyst-supported carbon on which a catalyst for promoting a power generation reaction is supported, and the anode The fuel cell, wherein the diffusion coefficient of water in the electrode is set to a different value by changing the mass of the catalyst-supporting carbon with respect to the mass of the electrolyte contained in the anode electrode.
According to this fuel cell, it is possible to more easily provide two or more regions having different water diffusion coefficients in the anode electrode.

[Application Example 14]
14. The fuel cell according to any one of Application Examples 1 to 13, further comprising a heating unit for heating the upstream side of the anode flow path outside the anode plate. ,Fuel cell.
According to this fuel cell, drying of the upstream portion of the anode can be promoted by the heating unit, and generation of flooding in the downstream portion of the cathode can be suppressed. Therefore, it is possible to suppress a decrease in power generation performance in the operating fuel cell.

[Application Example 15]
15. The fuel cell according to application example 14, wherein the heating unit is configured such that the anode electrode is within a range of ½ of the upstream side of the entire range from the first end to the second end. A fuel cell arranged to heat the upper region.
According to this fuel cell, the upstream portion of the anode in the above-mentioned range can be heated by the heating unit. Therefore, particularly when non-humidified oxidant gas is supplied, generation of flooding due to increase in operating temperature is prevented. Can be suppressed.

[Application Example 16]
The fuel cell according to Application Example 15, wherein the heating unit includes the anode electrode within a range of 3/8 on the upstream side of the entire range from the first end to the second end. A fuel cell arranged to heat the upper region.
According to this fuel cell, it is possible to further suppress the occurrence of flooding accompanying an increase in operating temperature when non-humidified oxidant gas is supplied.

[Application Example 17]
A fuel cell system comprising: the fuel cell according to any one of Application Examples 14 to 16, a dryness detection unit that detects a value related to the dryness of the electrolyte membrane, and the heating unit. A fuel cell stack including a plurality of power generation modules having the membrane electrode assembly sandwiched between the anode separator and the cathode separator. The heating unit includes first and second surfaces, includes a Peltier element capable of heating the first surface side and cooling the second surface side, and the heating unit includes the plurality of heating surfaces. Between the power generation modules, the first surface is opposed to the anode separator, and the second surface is opposed to the cathode separator, and the control unit When the detected value of the dryness detection unit is equal to or greater than a threshold value, the Peltier element is driven to promote moisture vaporization in the upstream portion of the anode in each of the plurality of power generation modules; A fuel cell system that promotes liquefaction of moisture in the side portion and increases the amount of moisture that moves through the electrolyte membrane from the cathode downstream portion to the anode upstream portion.
According to this fuel cell system, when the possibility of flooding is high, the Peltier element heats the upstream portion of the anode and cools the downstream portion of the cathode, thereby effectively suppressing the occurrence of flooding. be able to.

[Application Example 18]
The fuel cell according to any one of Application Examples 1 to 16, wherein the drying promotion mechanism is located upstream of the entire range from the first end to the second end. A fuel cell provided in a range of 1/2 of the above.
According to this fuel cell, in particular, when non-humidified oxidant gas is supplied, it is possible to suppress the occurrence of flooding accompanying an increase in operating temperature.

[Application Example 19]
The fuel cell according to Application Example 18, wherein the drying promotion mechanism is provided in a range of 3/8 upstream of the entire range from the first end to the second end. A fuel cell.
According to this fuel cell, it is possible to further suppress the occurrence of flooding accompanying an increase in operating temperature when non-humidified oxidant gas is supplied.

  The present invention can be realized in various forms, for example, in the form of a fuel cell, a fuel cell system including the fuel cell, a vehicle equipped with the fuel cell system, and the like. .

Schematic which shows the structure of the fuel cell in 1st Embodiment, and the structure of a seal | sticker integrated membrane electrode assembly. Schematic which shows the structure of the anode plate in 1st Embodiment. The schematic diagram for demonstrating the structure of the anode flow path provided in the anode plate in 1st Embodiment. Schematic which shows the structure of the cathode plate in 1st Embodiment. Schematic which shows the structure of the intermediate | middle plate in 1st Embodiment. Schematic which shows the structure of the anode plate used for the fuel cell of a comparative example. Explanatory drawing for demonstrating the fall of the electric power generation performance in the fuel cell of a comparative example. Explanatory drawing for demonstrating the fall of the electric power generation performance in the fuel cell of a comparative example. Explanatory drawing which shows the electric power generation performance in the fuel cell of 1st Embodiment. Explanatory drawing for demonstrating the structure of the anode flow path in the fuel cell of an Example. Schematic which shows the structure of the fuel cell of 2nd Embodiment, and the schematic which shows the structure of the flow-path groove | channel provided in the anode plate. Schematic which shows the structure of the fuel cell in 3rd Embodiment. Schematic which shows the structure of the anode plate and cathode plate which are used for the fuel cell of 3rd Embodiment. Explanatory drawing for demonstrating the heating area | region by the Peltier device in 3rd Embodiment. Explanatory drawing which shows the electric power generation performance in the fuel cell of 3rd Embodiment. Schematic which shows the structure of the fuel cell system using the fuel cell of 3rd Embodiment. The flowchart which shows the control procedure of the control part in the fuel cell system using the fuel cell of 3rd Embodiment. Schematic which shows the structure of the seal | sticker integrated membrane electrode assembly for every Example in 4th Embodiment. Schematic which shows the structure of the seal | sticker integrated membrane electrode assembly for every comparative example in 4th Embodiment. Explanatory drawing which shows the electric power generation performance of the fuel cell of 4th Embodiment. Schematic which shows the structure of the fuel cell in 5th Embodiment. Schematic which shows the structure of the refrigerant | coolant flow path of the fuel cell in 5th Embodiment. The schematic diagram for demonstrating the movement of the heat | fever to the refrigerant | coolant flow path in 5th Embodiment. The reference figure for demonstrating the change of the electric power generation performance by the difference in the thermal conductivity of a separator. Explanatory drawing which shows the electric power generation performance in the fuel cell of 5th Embodiment. Schematic which shows the other structural example of the fuel cell in 5th Embodiment.

A. First embodiment:
FIG. 1A is a schematic diagram showing a configuration of a fuel cell 100 as an embodiment of the present invention. The fuel cell 100 is a polymer electrolyte fuel cell that generates power by receiving supply of hydrogen and oxygen as reaction gases. The fuel cell 100 has a stack structure in which seal-integrated membrane electrode assemblies 10 and separators 15 are alternately stacked. In addition, an insulator plate, a terminal plate, an end plate, and the like are further stacked at both ends in the stacking direction of the fuel cell 100, and the fuel cell 100 is given a fastening force along the stacking direction by a fastening member. .

  The seal-integrated membrane / electrode assembly 10 includes a membrane / electrode assembly 5 which is a power generator in which an anode electrode 2 and a cathode electrode 3 are provided on both sides of an electrolyte membrane 1. The electrolyte membrane 1 is a solid polymer thin film that exhibits good proton conductivity in a wet state. The anode electrode 2 and the cathode electrode 3 are formed by applying and drying catalyst ink on the outer surface of the electrolyte membrane 1. Here, “catalyst ink” means a mixed solution obtained by mixing a catalyst-carrying carbon carrying a catalyst (for example, platinum (Pt)) for promoting a power generation reaction and an electrolyte solution. A seal portion 9 is integrally formed on the outer periphery of the membrane electrode assembly 5. The seal portion 9 is formed by injection molding a thermosetting resin member so as to cover the outer peripheral ends of the electrolyte membrane 1, the anode electrode 2, and the cathode electrode 3.

  FIG. 1B is a schematic diagram for explaining the configuration of the seal-integrated membrane electrode assembly 10. FIG. 1B is a schematic view when the seal-integrated membrane electrode assembly 10 is viewed along the direction of arrow B in FIG. Here, in the seal-integrated membrane electrode assembly 10, a region surrounded by the seal portion 9 and generating power upon receiving the reaction gas is referred to as a “power generation region GA”. Manifolds 61 to 66 for reaction gas and refrigerant are provided as through holes on opposite sides of the seal portion 9 across the power generation area GA. Specifically, with respect to the power generation area GA, a hydrogen supply manifold 61, a refrigerant supply manifold 65, and an oxygen discharge manifold 64 are arranged in a line in order from the upper side of the drawing on the left side of the drawing. Further, an oxygen supply manifold 63, a refrigerant discharge manifold 66, and a hydrogen discharge manifold 62 are arranged in a row in order from the upper side of the drawing on the right side of the drawing with respect to the power generation area GA.

  In this specification, the direction in which the reactant gas supply manifolds 61 and 63 and the discharge manifolds 62 and 64 face each other (the left-right direction in FIG. 1B) is referred to as the “manifold facing direction”. Call. Further, a direction (vertical direction in FIG. 1B) in which the manifolds 61, 65, 64 or the manifolds 63, 66, 62 are arranged along one side of the power generation area GA is perpendicular to the manifold facing direction. This is called “array direction”. In the fuel cell 100, the arrangement of the manifolds 61 to 64 causes the hydrogen flow direction and the oxygen flow direction in the power generation region GA to face each other when viewed along the manifold arrangement direction. (FIG. 1A).

  Further, in the present specification, the hydrogen upstream end or the oxygen downstream end in the manifold facing direction of the power generation region GA is hereinafter referred to as “hydrogen upstream end” or “oxygen downstream end” (FIG. 1B )). On the other hand, the end portion on the hydrogen downstream side or the end portion on the oxygen upstream side in the manifold facing direction of the power generation region GA is referred to as “hydrogen downstream end” or “oxygen upstream end”.

  The separator 15 is a so-called three-layer separator including an anode plate 20, a cathode plate 30, and an intermediate plate 40 sandwiched between the two plates 20 and 30. When configuring the fuel cell 100, the anode plate 20 is disposed on the anode electrode 2 side of the seal-integrated membrane electrode assembly 10, and the cathode plate 30 is disposed on the cathode electrode 3 side. In this specification, a power generation module including at least the seal-integrated membrane electrode assembly 10 and the two plates 20 and 30 sandwiching the seal-integrated membrane electrode assembly 10 is referred to as a “single cell”. .

  Here, the gas flow path members 7 are disposed between the anode plate 20 and the anode electrode 2 and between the cathode plate 30 and the cathode electrode 3, respectively. The gas flow path member 7 is composed of a conductive porous member, functions as a gas flow path (gas diffusion layer) for spreading the reaction gas over the entire anode electrode 2 and cathode electrode 3, and is a membrane electrode. It functions as a conductive path between the joined body 5 and the separator 15. The gas flow path member 7 can be made of carbon paper, so-called expanded metal, or punching metal.

  Similar to the seal-integrated membrane electrode assembly 10, the manifolds 61 to 66 are provided as through holes in the plates 20 to 40 of the separator 15. Each plate 20 to 40 is formed with a fluid flow path for connecting each manifold 61 to 66 and the power generation area GA of the membrane electrode assembly 10 with an integrated seal. Below, the structure of the fluid flow path provided in each plate 20-40 is demonstrated.

  FIG. 2 is a schematic view showing the configuration of the anode plate 20. FIG. 2 shows a surface (hereinafter referred to as “anode facing surface”) of the surface of the anode plate 20 facing the anode electrode 2 of the seal-integrated membrane electrode assembly 10 when the fuel cell 100 is configured. ing. In FIG. 2, the outer shape of a region overlapping the power generation region GA of the seal-integrated membrane electrode assembly 10 when the fuel cell 100 is viewed along the stacking direction is illustrated by a one-dot chain line.

  On the anode-facing surface of the anode plate 20, first and second parallel passage grooves 21a and 21b and first and second connection passage grooves 22a and 22b are provided as passage grooves constituting a hydrogen passage. And the 1st and 2nd manifold communication channel grooves 23a and 23b are provided. The first parallel flow channel grooves 21a are a plurality of flow channel grooves extending in parallel along the manifold facing direction in the power generation region GA. Similarly, the second parallel flow channel grooves 21b are a plurality of flow channel grooves extending in parallel along the manifold facing direction in the power generation region GA. The first and second parallel passage grooves 21a and 21b are alternately arranged in the power generation area GA. Further, the first and second parallel passage grooves 21 a and 21 b are divided by a partition wall 26.

  The first and second connection flow channel grooves 22a and 22b are flow channel grooves that run along the manifold arrangement direction at the hydrogen upstream end and the hydrogen downstream end of the power generation region GA, respectively. The first connection channel groove 22a is provided on the hydrogen upstream side, and is connected to the end portion on the hydrogen upstream side of all the first parallel channel grooves 21a. Hydrogen can be spread in the manifold arrangement direction of the power generation region GA by the first connection flow channel groove 22a. On the other hand, the second connection channel groove 22b is provided on the hydrogen downstream side, and is connected to the end portion on the hydrogen downstream side of all the second parallel channel grooves 21b.

  The first manifold communication channel groove 23a is a channel groove connected to the first connection channel groove 22a, and is provided between the hydrogen supply manifold 61 and the first connection channel groove 22a. Yes. The first manifold communication channel groove 23 a is provided with a through hole 25 a that communicates with a hydrogen supply channel groove 44 a (described later) provided in the intermediate plate 40. The hydrogen in the hydrogen supply manifold 61 is supplied into the power generation area GA through the first manifold communication channel groove 23a. The second manifold communication channel groove 23b is a channel groove connected to the second connection channel groove 22b, and is provided between the hydrogen discharge manifold 62 and the second connection channel groove 22b. Yes. The second manifold communication channel groove 23b is provided with a through hole 25b communicating with a hydrogen discharge channel groove 44b (described later) provided in the intermediate plate 40. The anode exhaust gas containing hydrogen that has not been subjected to the power generation reaction is discharged to the outside of the power generation area GA through the second manifold communication channel groove 23b.

  3A and 3B are schematic diagrams for explaining the flow of hydrogen in the power generation region GA. FIG. 3A schematically shows the flow channel grooves 21a, 21b, 22a, 22b provided in the power generation area GA described in FIG. 2, and arrows indicating the flow of hydrogen. In FIG. 3A, for convenience, the flow channel on the supply side (first parallel flow channel groove 21a and first connection flow channel groove 22a) and the flow channel on the discharge side (second parallel flow) The channel groove 21b and the second connection channel groove 22b) are shown separately by being given different hatchings. FIG. 3B shows a partial schematic cross section of the fuel cell 100 at a portion corresponding to BB cutting shown in FIG. 3A, and shows the anode plate 20, the membrane electrode assembly 5, and the gas flow path member. 7 is schematically illustrated.

  Hydrogen that has flowed into the power generation region GA branches to all the first parallel flow channel grooves 21a via the first connection flow channel grooves 22a. The hydrogen in the first parallel flow channel groove 21a flows to the downstream side of the hydrogen and also flows into the gas flow channel member 7, and is supplied to the power generation reaction in the anode electrode 2. Here, during the operation of the fuel cell 100, a part of the water generated on the cathode electrode 3 side by the power generation reaction moves to the anode electrode 2 side through the electrolyte membrane 1. The hydrogen that has not been subjected to the power generation reaction in the anode electrode 2 is humidified by the moisture that has moved to the anode electrode 2 side, and flows into the second parallel passage groove 21b, and further, the second Is discharged to the outside of the power generation area GA through the connection flow channel groove 22b.

  As described above, the flow path groove for hydrogen provided in the anode plate 20 is provided on the supply side flow path grooves 21 a and 22 a communicating with the hydrogen supply manifold 61 and on the discharge side communicating with the hydrogen discharge manifold 62. It is comprised by the flow-path groove | channels 21b and 22b. As described above, the supply-side channel grooves 21a and 22a and the discharge-side channel grooves 21b and 22b are separated by the partition wall 26 (FIG. 2) between the first and second parallel channel grooves 21a and 21b. It is divided. Further, in the anode plate 20, the hydrogen in the first parallel passage groove 21 a is guided into the gas passage member 7 by the partition wall 26.

  FIG. 4 is a schematic view showing the configuration of the cathode plate 30. FIG. 4 shows a surface (hereinafter referred to as “cathode facing surface”) of the surface of the cathode plate 30 facing the cathode electrode 3 of the seal-integrated membrane electrode assembly 10 when the fuel cell 100 is configured. Yes. In FIG. 4, a region that overlaps the power generation region GA of the seal-integrated membrane electrode assembly 10 when the fuel cell 100 is viewed in the stacking direction is indicated by a one-dot chain line.

  The cathode facing surface of the cathode plate 30 includes a plurality of parallel flow channel grooves 31, first and second connection flow channel grooves 32a and 32b, and first and second manifold communication flow channel grooves 33a and 33b. Is provided. The parallel flow passage grooves 31 are a plurality of flow passage grooves provided in parallel extending in the manifold facing direction in the power generation region GA. The first and second connection channel grooves 32a and 32b are channel grooves provided along the manifold arrangement direction at the oxygen upstream end or oxygen downstream end of the power generation region GA, respectively. The first connecting channel groove 22a is connected to the end of the parallel channel groove 31 on the oxygen upstream side, and the second connecting channel groove 32b is the end of the parallel channel groove 31 on the oxygen downstream side. Connected to the department.

  The first manifold communication channel groove 33a is a channel groove connected to the first connection channel groove 32a, and is provided between the oxygen supply manifold 63 and the first connection channel groove 32a. Yes. The first manifold communication channel groove 33 a is provided with a through hole 35 a that communicates with an oxygen supply channel groove 45 a (described later) provided in the intermediate plate 40. The second manifold communication channel groove 33b is a channel groove connected to the second connection channel groove 32b, and is provided between the oxygen exhaust manifold 64 and the second connection channel groove 32b. Yes. The second manifold communication channel groove 23b is provided with a through hole 35b communicating with an oxygen discharge channel groove 45b (described later) provided in the intermediate plate 40.

  Oxygen in the oxygen supply manifold 63 flows into the first connection channel groove 32 a via the first manifold communication channel groove 33 a and branches into the parallel channel grooves 31. In the power generation area GA, oxygen flows downstream while being subjected to a power generation reaction. The cathode exhaust gas containing oxygen that has not been subjected to the power generation reaction flows from each parallel flow channel groove 31 into the second connection flow channel groove 32b and passes through the second manifold communication flow channel groove 33b. And discharged outside the power generation area GA.

  5A and 5B are schematic views showing the configuration of the intermediate plate 40. FIG. FIG. 5A shows the surface side in contact with the anode plate 20 when the separator 15 is configured, and FIG. 5B shows the surface side in contact with the cathode plate 30. 5A and 5B, the outer shape of the region overlapping the power generation region GA of the seal-integrated membrane electrode assembly 10 when the fuel cell 100 is viewed along the stacking direction is indicated by a one-dot chain line. It is shown.

  The intermediate plate 40 has a hollow portion 42 in a region corresponding to the power generation region GA. The hollow portion 42 is connected to refrigerant manifolds 65 and 66. A plurality of flow path walls 43 extending in the manifold facing direction are arranged in parallel inside the hollow portion 42 to form a flow path for the refrigerant. That is, in the fuel cell 100, the power generation area GA is cooled by the refrigerant flowing in the hollow portion 42 of the intermediate plate 40 during the operation.

  Further, on the surface side of the intermediate plate 40 in contact with the anode plate 20, a channel groove 44 a for connecting the two through holes 25 a and 25 b (FIG. 2) of the anode plate 20 and the manifolds 61 and 62 for hydrogen. , 44b are provided (FIG. 5A). Further, on the surface side of the intermediate plate 40 in contact with the cathode plate 30, a flow channel 45 a for connecting the two through holes 35 a and 35 b (FIG. 3) of the cathode plate 30 and the manifolds 63 and 64 for oxygen. , 45b (FIG. 5B). In other words, the manifolds 61 and 62 for hydrogen or the manifolds 63 and 64 for oxygen and the anode plate 20 or the cathode plate 30 are provided via the flow channel grooves 44a, 44b, 45a and 45b provided in the intermediate plate 40. The respective channel grooves thus formed communicate with each other.

  Thus, in the fuel cell 100, the hydrogen flow direction and the oxygen flow direction in the power generation region GA are opposed to each other. Thereby, it is possible to suppress the power generation distribution in each single cell from being shifted to the hydrogen upstream side or the oxygen upstream side. However, even when the flow direction of the reaction gas is configured in this way, when oxygen is supplied without humidification, the power generation distribution becomes non-uniform as in the fuel cell of the comparative example described below. May end up.

  FIG. 6 is a schematic diagram showing a configuration of an anode plate 20a used in a fuel cell 100a as a comparative example with respect to the present embodiment. FIG. 6 is substantially the same as FIG. 2 except that a parallel flow channel groove 24 is formed instead of the first and second parallel flow channel grooves 21a and 21b. In addition, the other structure of the fuel cell 100a of a comparative example is the same as the structure of the fuel cell 100 of this embodiment.

  The parallel passage groove 24 of the anode plate 20a is a plurality of parallel passage grooves extending along the manifold facing direction, and both ends thereof are connected to the first and second connection passages 22a and 22b, respectively. . That is, the anode plate 20 a has the same channel groove configuration as the cathode plate 30. In the fuel cell 100a of the comparative example, the hydrogen flow direction and the oxygen flow direction in the power generation region GA are opposed to each other, as in the fuel cell 100 of the present embodiment.

FIGS. 7A and 7B and FIGS. 8A and 8B are explanatory diagrams for explaining a decrease in power generation performance in the fuel cell 100a of the comparative example. FIGS. 7A and 7B and FIGS. 8A and 8B show graphs showing the state of the power generation region GA in the single cell of the fuel cell 100a for each operating temperature. In these graphs, the horizontal axis is the position between the oxygen upstream end and the oxygen downstream end of the power generation region GA, and the overvoltage Ov, current density I, oxygen partial pressure P _O2 , film in the power generation region GA of each single cell are shown. A representative value of the degree of dryness D _MEA of the electrode assembly (MEA) is shown. The horizontal axis of these graphs corresponds to the arrow U in FIG.

The overvoltage Ov represents the difference between the voltage that can be theoretically output in the single cell and the actual output voltage, and the single cell with extremely high overvoltage may be unable to generate power. In each graph, the region of the overvoltage Ov in which the single cell is likely to be unable to generate power is indicated by hatching. The current density I corresponds to the amount of power generation in the single cell, and the amount of water generated at the cathode electrode 3 of each single cell can be estimated from the change in the current density I. The oxygen partial pressure P _O2 corresponds to the amount of oxygen supplied to the cathode electrode 3 of the single cell. MEA dryness degree D _MEA is an index indicating the dryness of the membrane electrode assembly 5, and decreases as the amount of water contained in the membrane electrode assembly 5 increases, and the amount of water contained in the membrane electrode assembly 5 decreases. It gets higher.

  FIG. 7A shows a state when the operating temperature is normal temperature (for example, 60 ° or less). Note that non-humidified hydrogen and oxygen are supplied as the reaction gas. At this operating temperature, the membrane / electrode assembly 5 is entirely wet by the generated water in the cathode electrode 3, and a power generation amount corresponding to the oxygen supply amount is obtained. Further, the overvoltage Ov in the U direction of the power generation area GA is in a substantially uniform state. That is, this graph shows a state in which the fuel cell 100a is operating satisfactorily.

FIG. 7B shows a state in which the operation of the fuel cell 100a of the comparative example is continued and the operation temperature becomes a temperature near the average operation temperature (for example, about 80 °). Here, the “average operation temperature” means a time average of the temperature of the entire fuel cell when the fuel cell is continuously operated. At this time, as the operating temperature rises, the saturated water vapor pressure of the supplied oxygen also rises, so that the degree of dryness D _MEA of the membrane electrode assembly 5 rises at the upstream end of oxygen. Along with this, the power generation reaction is suppressed, and the oxygen consumption is reduced on the upstream side of oxygen, so that the change in the oxygen partial pressure P _O2 becomes gradual, and the power generation amount (current density I) is locally reduced on the downstream side. An area that increases is generated. As the amount of power generated locally increases, the amount of water produced in the region also increases. In this region, the catalyst layer pores, which are oxygen channels in the cathode electrode 3, are clogged by the produced water (flooding). First, the overvoltage Ov increases.

FIG. 8A shows a state where the operating temperature of the fuel cell 100a of the comparative example further increases, for example, about 80 ° to 85 °. At this time, drying of the membrane electrode assembly 5 proceeds on the oxygen upstream side, and moisture moves to the downstream side according to the flow of oxygen. Therefore, the degree of drying of the MEA between the upstream side and the downstream side of the oxygen D _MEA A big difference occurs. When water is locally present on the oxygen downstream side in this way, the oxygen channel blockage in the cathode electrode 3 on the oxygen downstream side is further promoted, so that the overvoltage Ov in the region about half of the oxygen downstream side is significantly increased. Begin to.

  FIG. 8B shows a state when the operating temperature further rises from the state described in FIG. 8A in the fuel cell 100a of the comparative example. If the operation of the fuel cell 100a is continued in the state shown in FIG. 8A, the overvoltage Ov in the approximately half region on the oxygen downstream side continues to increase and reaches a region where power generation is impossible. That is, the power generation capability of the fuel cell 100a is significantly reduced due to the occurrence of so-called flooding. Thus, in the case where the operation is continued by supplying non-humidified oxygen to the fuel cell, there is a high possibility that moisture will concentrate on the oxygen downstream side as the operation temperature rises. In this case, since the drainage performance on the cathode electrode 3 side has decreased, the flooding is eliminated by inducing moisture to the anode electrode 2 side and improving drainage performance on the anode electrode 2 side. It is preferable.

Here, in general, wastewater N _a from the cathode electrode side of the unit cell of the fuel cell to the anode electrode side is expressed by the following equation (1).
N _a = D _ca / δ _ca · (C _c −C _a ) (1)
Here, D _ca is a moisture diffusion coefficient between the boundary surface between the electrolyte membrane 1 and the cathode electrode 3 and the boundary surface between the anode plate 20 (20a) and the gas flow path member 7. δ _ca is the distance from the boundary surface between the electrolyte membrane 1 and the cathode electrode 3 to the boundary surface between the anode plate 20 and the gas flow path member 7. C _c is the water concentration at the interface between the electrolyte membrane 1 and the cathode electrode 3, is C _a a water concentration in the channel of the hydrogen between the anode electrode 2 and the anode plate 20 (20a).

From this equation (1), it can be seen that the amount of moisture transferred to the anode electrode 2 can be increased by increasing the difference between the two moisture concentrations C _c and C _a . That is, by promoting the drying of the electrolyte membrane 1 on the anode electrode 2 side, moisture concentrated in the oxygen downstream side portion of the cathode electrode 3 is moved to the hydrogen upstream side portion closer to the hydrogen upstream end of the anode electrode 2, The amount of drainage from the electrode 2 side can be increased. Further, by moving the moisture to the anode electrode 2 side, the moisture can be further moved to the hydrogen downstream side, that is, the oxygen upstream side that tends to dry according to the flow of hydrogen. It is possible to improve the non-uniformity of the distribution. As a result, even when oxygen is supplied without humidification, the operation of the fuel cell 100 can be favorably continued.

  Here, in the fuel cell 100 of the present embodiment, the hydrogen that has flowed into the flow channel grooves 21a and 22a on the supply side of the anode plate 20 once passes through the gas flow channel member 7, and then the flow channel grooves 21b on the discharge side. It flows to 22b (FIG. 3). That is, according to the configuration of the flow channel groove of the anode plate 20, the amount of hydrogen flowing into the gas flow channel member 7 can be increased, so that the hydrogen flow rate in the gas flow channel member 7 increases, and this large flow rate is increased. By this, drying can be promoted. Then, the amount of moisture that moves from the cathode electrode 3 side through the electrolyte membrane 1 increases as the anode electrode 2 side is dried by a large hydrogen flow rate. Therefore, the occurrence of flooding on the cathode electrode 3 side can be suppressed. The anode plate 20 is provided with discharge-side flow channel grooves 21b and 22b used for discharging the anode exhaust gas. Accordingly, discharge of the anode exhaust gas containing humidified hydrogen is promoted by the flow path grooves 21b and 22b on the discharge side, so that drainage from the anode electrode 2 side in the fuel cell 100B is improved and flooding is generated. It is suppressed.

  FIG. 9 is an explanatory diagram showing experimental results for explaining the improvement in power generation performance by the configuration of the fuel cell 100 of the present embodiment. In FIG. 9, the relationship between the cell temperature and the cell voltage measured in the fuel cell having the same configuration as the fuel cell 100 of the present embodiment is shown as a graph Ge of the example. Here, “cell voltage” means the average value of the voltage measured for each single cell in the fuel cell, and “cell temperature” means the average of the temperature measured for each single cell in the fuel cell. Mean value. FIG. 9 shows a measurement result of the cell temperature and the cell voltage in a fuel cell having the same configuration as the fuel cell 100a of the comparative example described above as a graph Gc of the comparative example.

  Here, in the electrolyte membrane 1 of the fuel cell of Examples and Comparative Examples, a perfluorocarbon polymer having a sulfonic acid group (ion exchange group capacity: about 1.0 meq / g) was dissolved in a solvent containing water and alcohols. The electrolyte solution was obtained by applying and drying. The anode electrode 2 and the cathode electrode 3 were formed from a catalyst ink obtained by mixing the above electrolyte solution and catalyst-supported carbon black having a platinum catalyst weight ratio of about 0.5. The catalyst ink for the anode has a mass ratio of the electrolyte to the catalyst-carrying carbon black of 1.0: 0.5, and the catalyst ink for the cathode has a mass ratio of the electrolyte to the catalyst-carrying carbon black of 1.0. : 0.3.

Further, in measuring the cell voltage, air of 1.5 times the stoichiometric ratio was supplied to the cathode 3 side of each fuel cell at a pressure of about 50 kPaG without humidification. On the other hand, 1.2 times the stoichiometric amount of hydrogen was supplied to the anode electrode 2 side at a pressure of about 50 kPaG without humidification. Further, the cell temperature in each fuel cell was gradually raised from 70 ° C., and the current value of each single cell was kept substantially constant at about 1.0 A / cm ² .

  FIGS. 10A and 10B are explanatory views for explaining the configuration of the flow channel grooves provided in the fuel cell of the example. FIG. 10A is a schematic view schematically showing the cross-sectional shapes of the first and second parallel passage grooves 21a and 21b in the fuel cell of the example. In the fuel cell of the embodiment, the flow passage cross-sectional area of the first parallel flow passage groove 21a is configured to be smaller than the flow passage cross-sectional area of the second parallel flow passage groove 21b. In the figure, the channel cross-sectional area is changed by changing the depth of the channel groove, but the channel cross-sectional area may be changed by changing the width of the channel groove. . By configuring the first and second parallel passage grooves 21a and 21b as described above, the flow rate of hydrogen on the anode electrode 2 side can be increased toward the upstream side.

FIG. 10B is a graph showing a result of calculating the flow rate of hydrogen on the anode electrode 2 side in the fuel cell of the example based on the shape of the channel groove. In this graph, the horizontal axis represents a position X (referred to as a “hydrogen channel position”) in the manifold facing direction when the position of the hydrogen upstream end of the power generation region GA is 0 and the position of the hydrogen downstream end is 1. . The horizontal axis X of this graph corresponds to the arrow X in FIG. Incidentally, the position of the upstream end of the second adjacent parallel flow grooves 21b and d _1, there is shown the position of the downstream end of the first adjacent parallel flow grooves 21a as d _2. As shown in the graph HV, the first and second parallel flow channel grooves 21a and 21b in the fuel cell of the example have a hydrogen flow rate position between 0 and 3/8 (illustrated by hatching). The flow rate is remarkably lowered, and the hydrogen flow rate position X is 3/8 or later, so that the hydrogen flow rate is substantially constant.

From the graph of FIG. 9, the cell voltage of the fuel cell of the example is higher than that of the fuel cell of the comparative example over the entire cell temperature. In particular, when the cell temperature becomes higher than the average operating temperature T _avg (for example, about 80 ° C.) of the fuel cell, the difference becomes remarkable. Thus, it can be seen that the shape of the flow channel in the anode plate 20 (FIG. 2) of the present embodiment is preferable to the shape of the flow channel in the anode plate 20a (FIG. 6) of the comparative example.

  Further, the fuel cell of the embodiment is configured such that the hydrogen flow rate on the anode electrode 2 side becomes faster toward the upstream side. Therefore, drying of the electrolyte membrane 1 on the upstream side of hydrogen can be further promoted, and moisture movement on the downstream side of hydrogen on the anode electrode 2 side can be promoted, so that the water distribution of the membrane electrode assembly 5 can be more effective. Can be improved. In addition, it is preferable that the flow path groove of the anode plate 20 has a configuration in which the hydrogen flow rate is higher toward the upstream side in the range where the hydrogen flow position X is 0 to 1/2, and in such a range as 0 to 3/8. It is more preferable to have a structure (FIG. 10B).

  Thus, according to the fuel cell 100 of the present embodiment, the supply side parallel flow channel groove 21a, the discharge side parallel flow channel groove 21b, and the gas flow channel member 7 separated by the partition wall 26 are used as the electrolyte upstream of the hydrogen. It functions as a drying promotion mechanism that promotes drying of the membrane 1. This drying promotion mechanism can promote the movement of moisture from the oxygen downstream side on the cathode electrode 3 side to the hydrogen upstream side on the anode electrode 2 side, and when the fuel cell 100 is operated, the power generation performance is reduced due to the occurrence of flooding. Can be suppressed. The fuel cell 100 can obtain the effect particularly when non-humidified oxygen is supplied.

B. Second embodiment:
FIG. 11 is a schematic diagram showing a configuration of a fuel cell 100B as a second embodiment of the present invention. FIG. 11A is the same as FIG. 1A except that the anode plate 20B is shown in place of the anode plate 20 and an arrow indicating the flow of hydrogen is added to the gas flow path member 7. FIG. ). The configuration of the fuel cell 100B is substantially the same as the configuration of the fuel cell 100 of the first embodiment except for the anode plate 20B.

  FIG. 11B is a schematic diagram showing the configuration of the anode plate 20B. FIG. 11B is substantially the same as FIG. 2 except that the first parallel flow channel groove 21a is omitted and the length of the second parallel flow channel groove 21b is shortened. In the anode plate 20B, the first connecting flow channel groove 22a and the second parallel flow channel groove 21b are divided by the partition wall 27.

  The hydrogen supplied from the hydrogen supply manifold 61 via the intermediate plate 40 is distributed in the manifold arrangement direction of the power generation area GA by the first connection flow channel groove 22a. Hydrogen in the first connecting channel groove 22a flows into the gas channel member 7 along the wall surface of the partition wall 27 between the two channel grooves 22a and 21b, and is supplied to the power generation reaction in the anode electrode 2. While flowing, it flows along the manifold facing direction (arrow in FIG. 11A). Hydrogen that has not been subjected to the reaction at the anode electrode 2 is humidified by the moisture of the anode electrode 2 and then flows into the second parallel flow channel groove 21b. 2 is discharged to the hydrogen discharge manifold 62 through the manifold communication channel groove 23b.

  As described above, according to the anode plate 20B, the amount of hydrogen flowing into the gas flow path member 7 in the region between the first connection flow path groove 22a and the second parallel flow path groove 21b is reduced in the first implementation. The number of anode plates 20 can be increased. In addition, the second parallel running channel groove 21b improves the discharge performance of the anode exhaust gas on the downstream side of the power generation area GA, so that the drainage performance from the anode electrode 2 side in the fuel cell 100B is improved and the occurrence of flooding is suppressed. The That is, in the fuel cell 100B of the second embodiment, the first connecting channel groove 21a, the second parallel channel groove 22b, the partition wall 27, and the gas channel member 7 of the anode plate 20B are the anode electrode 2. It functions as a drying promotion mechanism that promotes drying of the electrolyte membrane 1 on the side.

  The partition wall 27 between the first connecting channel groove 22a and the upstream end of the second parallel channel groove 21b is 1/2 of the upstream side of the entire range from the hydrogen upstream end to the hydrogen downstream end. Preferably, it is provided within the range of 3/8, and more preferably within the range of 3/8 on the upstream side. Thereby, drying of the anode electrode 2 can be promoted in a region corresponding to the range.

  Thus, according to the fuel cell 100B of the second embodiment, the movement of moisture from the oxygen downstream side of the cathode electrode 3 to the hydrogen upstream side of the anode electrode 2 is promoted as in the fuel cell 100 of the first embodiment. And generation of flooding can be suppressed.

C. Third embodiment:
FIG. 12 is a schematic diagram showing the configuration of a fuel cell 100C as the third embodiment of the present invention. The fuel cell 100C includes a single cell 110 that is a power generation module and a temperature control plate 210, and has a stack structure in which the single cells 110 and the temperature control plate 210 are alternately stacked. The single cell 110 includes a seal-integrated membrane electrode assembly 10, an anode plate 20C, a cathode plate 30C, and a gas flow path member 7. The seal-integrated membrane electrode assembly 10 and the gas flow path member 7 are the same as those described in the first embodiment. The anode plate 20C and the cathode plate 30C function as a separator that holds the seal-integrated membrane electrode assembly 10 from both sides.

  FIGS. 13A and 13B are schematic views showing the configurations of the anode plate 20C and the cathode plate 30C, respectively. FIG. 13A shows the anode facing surface of the anode plate 20C, except that the first and second manifold communication channel grooves 23a and 23b and the two through holes 25a and 25b are not provided. Is substantially the same as FIG. The anode plate 20C is provided with a communication channel that connects the first and second connection channel grooves 22a and 22b and the hydrogen manifolds 61 and 62, respectively. Is omitted.

  FIG. 13B shows the cathode facing surface of the cathode plate 30C, except that the first and second manifold communication channel grooves 33a and 33b and the two through holes 35a and 35b are not provided. Is substantially the same as FIG. The cathode plate 30C is provided with a communication channel that communicates the first and second connection channel grooves 32a and 32b with the oxygen manifolds 63 and 64, respectively. It is omitted.

  Here, in FIGS. 13A and 13B, the flow of hydrogen and oxygen in the anode plate 20C and the cathode plate 30C when the fuel cell 100C is operated is indicated by arrows, respectively. Note that the flow of hydrogen and oxygen in the communication channel (not shown) described above is indicated by broken-line arrows. Thus, in the fuel cell 100C of the third embodiment, the flow directions of hydrogen and oxygen are opposed to each other in the power generation region GA, similarly to the fuel cell 100B of the second embodiment described above. In the gas flow path member 7 of FIG. 12, the flow directions of hydrogen and oxygen in each single cell 110 are shown by white arrows and black arrows, respectively.

  The temperature control plate 210 (FIG. 12) is a conductive plate-like member having almost the same size as the single cell 110, and houses the Peltier element 211 therein. The Peltier element 211 has first and second surfaces 201 and 202. By receiving power from an external power source (not shown), the first surface 201 functions as a heating unit. The second surface 202 functions as a cooling unit. The Peltier element 211 is disposed such that the first surface 201 faces the anode plate 20C and the second surface 202 faces the cathode plate 30C. Note that the Peltier element 211 can generate electric power by the temperature difference when there is a temperature difference between the first surface 201 and the second surface 202 in a state where power is not supplied. is there.

  FIG. 14 is an explanatory diagram for explaining an arrangement position of the Peltier element 211 with respect to the seal-integrated membrane electrode assembly 10. FIG. 14 is substantially the same as FIG. 1B except that hatching indicating the region ha is added to the hydrogen upstream side in the power generation region GA. One or a plurality of Peltier elements 211 are arranged in the temperature control plate 210 so that the region ha can be heated.

  Here, an imaginary number straight line NL is assumed along the manifold facing direction where the hydrogen upstream end of the power generation region GA is 0 and the hydrogen downstream end is 1. At this time, the region ha is preferably a region provided in a range corresponding to a range of 0 to 1/2 of the virtual number line NL, and corresponds to a range of 0 to 3/8 on the virtual number line NL. A region provided in a range is more preferable. By heating the hydrogen flow path on the anode electrode 2 side in the region ha by the Peltier element 211, drying of the membrane electrode assembly 5 in the region ha is promoted, and the anode electrode 2 from the oxygen downstream side of the cathode electrode 3 is promoted. The amount of moisture that moves to the upstream side of hydrogen can be increased. That is, in this fuel cell 100C, the first surface 201 of the Peltier element 211 functions as a drying promotion mechanism that promotes drying of the electrolyte membrane 1 on the hydrogen upstream side on the anode electrode 2 side.

  By the way, according to the Peltier element 211, it is possible to heat the upstream side of hydrogen of the anode electrode 2 and cool the downstream side of oxygen of the cathode electrode 3. As a result, the liquefaction of water vapor on the oxygen downstream side of the cathode electrode 3 is promoted, and the moisture movement toward the anode electrode 2 according to the moisture concentration gradient can be further promoted.

  The temperature control plate 210 (FIG. 12) is provided with manifolds 61 to 66 like the seal-integrated membrane electrode assembly 10. Further, although the temperature control plate 210 is provided with a flow path for the refrigerant connecting the refrigerant manifolds 65 and 66 so as to avoid the arrangement position of the Peltier element 211, the illustration thereof is omitted. The temperature control plate 210 is preferably composed of a conductive member. Thereby, a conductive path between the anode plate 20C and the cathode plate 30C can be formed.

FIG. 15 is an explanatory diagram for explaining a change in the power generation performance of the fuel cell 100 </ b> C by the Peltier element 211. In the graph of FIG. 15, a change in the cell voltage with respect to the cell temperature when the fuel cell 100 </ b> C is operated while the upstream side of the anode electrode 2 is heated by the Peltier element 211 is shown by a graph G _h . Further, in the graph of FIG. 15, as a comparative example, a graph _Guh shows a change in the cell voltage with respect to the cell temperature when the fuel cell 100 </ b> C is operated while the heating by the Peltier element 211 is stopped. In addition, the fuel cell 100C heated the region ha provided in the range corresponding to the range of 0 to 3/8 on the virtual number line NL described above by the Peltier element 211. Further, hydrogen and oxygen were supplied to the fuel cell 100C without humidification, and a constant current was output to each unit cell 110.

As shown in these graphs G _h and G _uh , in the fuel cell 100C, the cell voltage becomes higher at a relatively high cell temperature T (for example, about 70 ° C.) when heating by the Peltier element 211 is performed. Yes. As described above, it can be inferred that moisture movement from the cathode electrode 3 is promoted on the hydrogen upstream side of the anode electrode 2 by heating or cooling by the Peltier element 211.

  By the way, when the temperature is lower than the relatively low cell temperature T, the cell voltage in the fuel cell 100C is higher when power is generated without driving the Peltier element 211. This is presumed to be because the moisture distribution in each single cell 110 is relatively uniform when the temperature is below this cell temperature (FIG. 7). Therefore, at a temperature equal to or lower than the cell temperature, the fuel cell 100C is preferably operated with the driving of the Peltier element 211 stopped. Therefore, it is possible to generate power more effectively by appropriately controlling the operation of the fuel cell 100C in the fuel cell system 200 described below.

  FIG. 16 is a schematic diagram showing a configuration of a fuel cell system using the fuel cell 100C. The fuel cell system 200 includes a fuel cell 100C, a Peltier element control unit 220, an external storage battery 230, a cell resistance monitor 240, and a control unit 250. In the fuel cell system 200, non-humidified oxygen is supplied to the fuel cell 100C together with hydrogen to generate power.

  The control unit 250 can be configured by, for example, a microcomputer, and executes control related to the operation of the fuel cell 100C, such as supplying a reactive gas in response to a request from an external load (not shown). The external storage battery 230 is an external power source that can be charged and discharged, and is connected to each Peltier element 211 provided in the fuel cell 100 </ b> C via the Peltier element control unit 220. The Peltier element control unit 220 includes, for example, a DC / DC converter, and controls power supply from the external storage battery 230 to the Peltier element 211 and charging of the electricity generated by the Peltier element 211 to the external storage battery 230. . The cell resistance monitor 240 detects the resistance value (cell resistance) of each single cell 110 and transmits it to the control unit 250. The control unit 250 executes control based on the value of the cell resistance detected by the cell resistance monitor 240.

  FIG. 17 is a flowchart showing a control procedure by the control unit 250 in the fuel cell system 200. This control procedure is periodically executed by the control unit 250 while the operation of the fuel cell 100C is continued. In step S <b> 10, the control unit 250 detects the cell resistance R of each single cell 110 using the cell resistance monitor 240.

  Here, in a fuel cell supplied with non-humidified oxygen, when the operating temperature rises, local flooding may occur on the downstream side of oxygen, and in this case, oxygen upstream of the membrane electrode assembly may occur. The dryness on the side increases (FIG. 8). In general, cell resistance tends to increase as the number of regions with high dryness increases in a membrane electrode assembly included in a single cell. Therefore, in this fuel cell system 200, the possibility of flooding occurring on the downstream side of the cathode electrode 3 increases as the unit cell 110 has a larger cell resistance R value. That is, in the fuel cell system 200, the cell resistance R is detected as a value related to the dryness of the membrane electrode assembly 5.

In step S20, the controller 250 compares the cell resistance R of each single cell 110 with a preset threshold value _Rupper . When at least one of the cell resistances R of each single cell 110 is equal to or higher than the threshold value R _upper , the control unit 250 determines that there is a high possibility that flooding has occurred in the fuel cell 100C. In this case, the control unit 250 causes the Peltier element control unit 220 to discharge the external storage battery 230, and starts heating of the anode electrode 2 side (cooling of the cathode electrode 3 side) by the Peltier element 211 (step S30).

On the other hand, when the cell resistance R of each single cell 110 is a value lower than the threshold value R _upper , the control unit 250 does not start supplying power from the external storage battery 230 to the Peltier element 211. The operation of the fuel cell 100C is continued (step S40). Alternatively, when power supply from the external storage battery 230 has already been started to the Peltier element 211, the control unit 250 stops the power supply and stops the heating / cooling process by the Peltier element 211. At this time, the Peltier element control unit 220 may cause the Peltier element 211 to generate power, and in this case, the generated electricity may be charged to the external storage battery 230.

Thus, in this fuel cell system 200, the possibility of occurrence of flooding in the fuel cell 100C is detected by detecting the cell resistance as a value associated with the degree of drying of the membrane electrode assembly. When it is determined that there is a high possibility that flooding has occurred, temperature control by the Peltier element 211 is started in order to suppress a decrease in power generation performance of the fuel cell 100C. The threshold value R _upper is preferably set to a value corresponding to the cell resistance when there is a high possibility of occurrence of flooding obtained in advance by experiments. Further, as the threshold value R _upper , a value corresponding to the cell resistance obtained when the cell temperature is higher than the temperature T (FIG. 15) or the average operating temperature of the fuel cell, which is obtained in advance through experiments or the like, is set good.

  Thus, according to the fuel cell 100C of the third embodiment, the temperature distribution of each single cell 110 can be improved by the temperature control of the single cell 110 by the Peltier element 211, and the power generation of the operating fuel cell 100C can be achieved. A decrease in performance can be suppressed. In addition, according to the fuel cell system 200 using the fuel cell 100C, when the possibility of flooding is high, temperature control by the Peltier element 211 is started, so that the fuel cell 100C can efficiently generate power. Is possible.

D. Fourth embodiment:
FIG. 18 is a schematic view showing a configuration of a seal-integrated membrane electrode assembly as a fourth embodiment of the present invention. Each of the FIG. 18 (A) ~ (C) , the seal-integrated type membrane electrode assembly 10D ₁ ~10D ₃ of Examples 1 to 3 are shown. The configurations of the seal-integrated membrane electrode assemblies 10D _{1 to} 10D 3 in Examples 1 to ₃ are the configurations of the seal-integrated membrane electrode assembly 10 described with reference to FIG. 1 except that the anode electrodes 2D have different configurations. Is almost the same. In FIG. 18, the left side toward the paper surface is the hydrogen upstream side, and the right side toward the paper surface is the hydrogen downstream side.

The anode electrode 2D of the seal-integrated type membrane electrode assembly 10D ₁ ~10D ₃ of the Examples 1-3, two anode region 2a where the ratio of the components are different, and a 2b. Specifically, the two anode regions 2a and 2b are provided in the following ranges. In the following description, the first and second anode regions 2a and 2b are assumed to be provided in the manifold arrangement direction of the power generation region GA in any of the examples and comparative examples.

Here, a hypothetical number line NL is assumed along the manifold facing direction in which the hydrogen upstream end in the power generation region GA is 0 and the hydrogen downstream end is 1. At this time, in the seal-integrated membrane electrode assembly 10D _{1 of} Example 1, the first anode region 2a is provided on the hydrogen upstream side with a position corresponding to the position of 3/8 on the imaginary number line as a boundary. The second anode region 2b is provided on the downstream side of hydrogen (FIG. 18A).

In the seal-integrated membrane / electrode assembly 10D _{2 of} Example 2, the first anode region 2a is moved from the position corresponding to 1/8 on the virtual number line NL to 3/8 on the virtual number line NL. It is provided up to a position corresponding to the position (FIG. 18B). Further, the seal-integrated type membrane electrode assembly 10D ₂ of Example 2, in a region other than the first anode region 2a, the second anode region 2b is provided. In the seal-integrated membrane electrode assembly 10D _{3 of} Example 3, the first anode region 2a is provided on the upstream side of hydrogen with a position corresponding to 1/4 position on the imaginary number line NL as a boundary, and the downstream side of hydrogen Is provided with a second anode region 2b (FIG. 18C).

Here, the electrolyte membrane 1 of each of the seal-integrated membrane electrode assemblies 10D _{1 to} 10D ₃ was manufactured as follows. First, a perfluorocarbon polymer having a sulfonic acid group (ion exchange group capacity of about 1.0 meq / g) was dissolved in a solvent containing water and alcohols to prepare an electrolyte solution. And the electrolyte membrane 1 was set by apply | coating and drying the electrolyte solution.

In addition, the cathode electrode 3 includes the above electrolyte solution and a catalyst-carrying carbon black having a platinum catalyst weight ratio of about 0.5, and a mass ratio of the electrolyte to the catalyst-carrying carbon black of 1.0: 0.3. It was formed with a catalyst ink obtained by mixing so that The cathode electrode 3 was formed so that the platinum content per unit area was 0.5 mg / cm ² .

Further, the catalyst ink for forming the first anode region 2a includes the electrolyte solution and catalyst-supported carbon black having a platinum catalyst weight ratio of about 0.5, and the mass of the electrolyte and the catalyst-supported carbon black. It was obtained by mixing so that the ratio was 1.0: 0.5. The catalyst ink for forming the second anode region 2b includes the above electrolyte solution and a catalyst-supported carbon black having a platinum catalyst weight ratio of about 0.5, and a mass ratio of the electrolyte to the catalyst-supported carbon black. It was obtained by mixing so that 1.0: 0.2. The anode electrode 2D was formed by applying and drying these catalyst inks to the regions where the first and second anode regions 2a and 2b of the electrolyte membrane 1 were formed. The anode electrode 2D was formed so that the platinum content per unit area was 0.2 mg / cm ² in both the first and second anode regions 2a and 2b.

Here, when the porosity of the anode electrode 2D was measured by mercury porosimetry, the porosity in the first anode region 2a was about 60%, and the porosity in the second anode region 2b was about 30%. . Generally, the diffusion coefficient in the porous body of water increases as the porosity of the porous body increases (the following formula (2)).
D _po = ε ^1.5 · D _gp (2)
D _po is the diffusion coefficient in the porous body of water, D _gp is the diffusion coefficient in the gas phase of water, and ε is the porosity of the porous body. That is, the first anode region 2a tends to dry more easily than the second anode region 2b. Further, in the equation (1) described in the first embodiment, D _ca in the first anode region 2a is larger than D _ca in the second anode region 2b. That is, in these seal-integrated membrane electrode assemblies 10D _{1 to} 10D 3 of Examples 1 to ₃ , the first anode region 2a has a larger drainage amount from the cathode electrode 3 side than the second anode region 2b. Become.

Figure 19 (A) ~ (D) are each a schematic diagram showing the structure of a seal-integrated type membrane electrode assembly 10d ₁ ~10d ₄ of Comparative Examples 1 to 4 in the fourth embodiment. Seal-integrated type membrane electrode assembly 10d ₁ ~10d ₄ of these Comparative Examples 1 to 4, except that the first and second anode regions 2a, 2b position formed of have different anode electrode 2D These are the same as the seal-integrated membrane electrode assemblies 10D _{1 to} 10D _{2 of} Examples 1 to 3. Note that FIGS. 19A to 19D illustrate a virtual number line NL similar to that described in FIG.

The anode electrode 2D of the seal-integrated type membrane electrode assembly 10d ₁ of Comparative Example 1, only the second anode region 2b is provided (FIG. 19 (A)). In seal-integrated type membrane electrode assembly 10d ₂ of Comparative Example 2, the first anode region 2a is provided in the region of the range corresponding to the range of 1 / 4-1 / 2 of the number of virtual straight line NL (Fig. 19 (B)). Further, the seal-integrated type membrane electrode assembly 10d ₂ of Comparative Example 2, in a region other than the first anode region 2a, the second anode region 2b is provided.

In the seal-integrated membrane electrode assembly 10d _{3 of} Comparative Example 3, the first anode region 2a is provided on the hydrogen upstream side of the power generation region GA with a position corresponding to a position corresponding to 1/2 of the imaginary number line as a boundary. The second anode region 2b is provided on the downstream side of hydrogen (FIG. 19C). In the seal-integrated membrane electrode assembly 10d _{4 of} Comparative Example 4, conversely, the second anode region 2b is provided in the half region on the hydrogen upstream side of the power generation region GA, and the first region in the half region on the downstream side of hydrogen. The anode region 2a is provided (FIG. 19D).

FIG. 20 is a graph showing the measurement results of the cell voltage with respect to the cell temperature in the fuel cell using the seal-integrated membrane electrode assemblies 10D _{1 to} 10D ₃ and 10d _{1 to} 10d ₄ of the above examples and comparative examples. In this measurement, gas flow path members were arranged on the outer surfaces of the anode electrode 2D and the cathode electrode 3 of each of the seal-integrated membrane electrode assemblies 10D _{1 to} 10D ₃ and 10d _{1 to} 10d ₄ . As the gas flow path member, water repellent carbon paper having a thickness of about 300 μm was used. The water repellent carbon paper was packed with water repellent carbon powder mixed with carbon black and PTFE. The water permeation start pressure of this gas flow path member was 150 kPa. In addition, as the separator, a separator having flow channel grooves similar to those of the anode plate 20C and the cathode plate 30C described in the third embodiment was used (FIG. 13).

In measuring the cell voltage, non-humidified air in an amount 1.5 times the stoichiometric ratio was supplied to the cathode 3 side of each fuel cell at a pressure of about 50 kPaG. On the other hand, non-humidified hydrogen in an amount 1.8 times the stoichiometric ratio was supplied to the anode 2D side at a pressure of about 50 kPaG. Furthermore, the cell temperature in each fuel cell was gradually raised from 60 ° C., and the output current of each single cell was kept substantially constant at about 1.0 A / cm ² .

  From this measurement result, the hydrogen downstream side is constituted by the second anode region 2b from the position corresponding to the position of 3/8 on the virtual number line NL, and the first anode region 2a is located in the hydrogen upstream region. It can be seen that it is preferable to contain. In particular, as in the second embodiment, the first anode region 2a is provided in the range of 1/8 to 3/8 on the virtual number line NL, and the second anode region 2b is provided in the other region. Preferably it is. In the first anode region 2a, moisture is more easily diffused than in the second anode region 2b. Therefore, the first anode region 2a functions as a drying promotion mechanism that promotes drying of the electrolyte membrane 1 on the upstream side of hydrogen in the anode electrode 2D. . Therefore, by forming the first anode region 2a in the above-described range, moisture movement from the oxygen downstream side of the cathode electrode 3 is promoted, and flooding is suppressed.

  As described above, the first and second anode regions 2a and 2b having different water diffusivities in the anode electrode 2D so that the diffusion coefficient of water on the upstream side of hydrogen is higher than the diffusion coefficient of water on the downstream side of hydrogen. By providing this, it is possible to suppress the occurrence of flooding in the fuel cell.

E. Fifth embodiment:
FIG. 21 is a schematic diagram showing the configuration of a fuel cell as a fifth embodiment of the present invention. This fuel cell 100E includes a seal-integrated membrane electrode assembly 10 similar to that described in the first to third embodiments, and a separator 15E for sandwiching the seal-integrated membrane electrode assembly 10. It has a stack structure that is alternately stacked. FIG. 21 is a view when viewed in the manifold facing direction, and illustration of each of the manifolds 61 to 66 is omitted.

  The separator 15E is a so-called two-layer separator that includes an anode plate 20E and a cathode plate 30E. Each of the two plates 20E and 30E is bent into a corrugated plate shape so as to be alternately uneven in the thickness direction, thereby forming a plurality of flow channel grooves that run along the manifold facing direction in the power generation region GA.

  The two plates 20E and 30E are joined so that the flow channel grooves face each other to form the separator 15E. As a result, in the separator 15E, a coolant channel 74 is formed between the anode plate 20E and the cathode plate 30E. Further, when the fuel cell 100E is configured, the hydrogen flow channel 71 is configured by the flow channel groove outside the anode plate 20E and the outer surface of the anode electrode 2, and the flow channel groove and cathode electrode outside the cathode plate 30E. 3, an oxygen flow path 72 is formed. In FIG. 21, the hydrogen flow direction in the hydrogen flow path 71 is the depth direction in the drawing, and the oxygen flow direction in the oxygen flow path 72 is the front direction in the drawing. A gas flow path member may be disposed between the separator 15E and the anode electrode 2 and the cathode electrode 3.

  22 is a schematic cross-sectional view showing a cross section of the separator 15E and the membrane electrode assembly 5 taken along the line AA of FIG. Note that FIG. 22 illustrates from the hydrogen upstream end to the hydrogen downstream end in the power generation region GA, and the illustration of other portions is omitted for the sake of convenience.

  A heat transfer suppressing member 76 is disposed in the refrigerant flow path 74 of the separator 15E. The heat transfer suppressing member 76 is a film-like resin member having a heat transfer coefficient higher than the heat transfer coefficients of the two plates 20E and 30E, and the refrigerant flow path 74 constituted by the anode plate 20E is upstream of the hydrogen. Affixed to the channel wall. Here, an imaginary number straight line NL is assumed along the manifold facing direction where the hydrogen upstream end of the power generation region GA is 0 and the hydrogen downstream end is 1. At this time, the heat transfer suppressing member 76 is preferably attached to a range corresponding to a range of 0 to 1/2 of the virtual number line NL, and corresponds to a range of 0 to 3/8 on the virtual number line NL. More preferably, it is attached to the range. The heat transfer suppressing member 76 can be made of a silicone polymer or a polyimide polymer when the separator 15E is made of stainless steel (SUS), titanium (Ti), aluminum (Al), or copper (Cu). .

  FIG. 23 is a schematic diagram for explaining heat transfer from the membrane electrode assembly 5 to the refrigerant flow path 74. FIG. 23 is a cross-sectional view of the fuel cell 100E similar to that of FIG. 21, and shows a part of the portion where the heat transfer suppressing member 76 is disposed. In FIG. 23, the heat transfer suppressing member 76 is indicated by a broken line. During the operation of the fuel cell 100E, heat generated by the power generation reaction is transferred from the anode electrode 2 side or the cathode electrode 3 side to the refrigerant in the refrigerant flow path 74. However, since the heat transfer suppressing member 76 is disposed on the anode electrode 2 side, heat transfer from the anode electrode 2 side to the refrigerant in the refrigerant flow path 74 is suppressed as compared with the cathode electrode 3 side.

  FIG. 24 is a reference diagram for explaining a change in the power generation performance of the fuel cell due to a difference in heat transfer coefficients of members constituting the separator. The graph of FIG. 24 shows the measurement results of changes in cell voltage and cell resistance with respect to cell temperature for two types of fuel cells having different separator components. Here, graph V1 and graph R1 show changes in cell voltage and cell resistance in a fuel cell (referred to as a “first fuel cell”) in which a separator is made of SUS coated with corrosion resistance. On the other hand, graph V2 and graph R2 show changes in cell voltage and cell resistance of a fuel cell (referred to as a “second fuel cell”) in which a separator is formed of Cu coated with corrosion resistance. Note that the heat transfer coefficient of SUS is 16 W / m · K, and the heat transfer coefficient of Cu is 390 W / m · k. Moreover, the other structure of the fuel cell made into the measurement object is the same as the fuel cell of 5th Embodiment.

  Here, in the first fuel cell, when the cell temperature becomes higher than T1, the cell resistance R1 increases remarkably and the cell voltage V1 decreases remarkably. On the other hand, in the second fuel cell, when the cell temperature becomes higher than T2, the cell resistance R2 increases remarkably and the cell voltage V2 decreases remarkably. In each of the first and second fuel cells, when the cell temperature becomes higher than the temperatures T1 and T2, the resistance between the anode and the cathode increases due to an increase in the drying region of the electrolyte membrane, and power generation due to a decrease in proton conductivity. Performance begins to decline. The temperature at which the power generation performance starts to decrease is significantly higher in the second fuel cell in which the heat transfer coefficient of the constituent members of the separator is higher (T1 <T2). This is because a fuel cell using a separator having a high heat transfer coefficient has a higher cooling effect by the refrigerant. Thus, generally, the lower the heat transfer coefficient of the separator, the better the power generation performance of the fuel cell at a high temperature.

  However, in the fuel cell 100E of the fifth embodiment, the heat transfer suppression member 76 locally increases the heat transfer coefficient of the separator 15E in a region where flooding is likely to occur. As described with reference to FIG. 8, when unhumidified oxygen is supplied in a fuel cell in which the flow direction of hydrogen and the flow direction of oxygen are opposed to each other, the downstream of the cathode increases as the operating temperature increases. This is because the possibility of occurrence of flooding on the side increases. In other words, in the fuel cell 100E, the heat transfer suppressing member 76 functions as a drying acceleration mechanism that promotes evaporation of moisture on the hydrogen upstream side of the anode electrode 2, so that the oxygen downstream side of the cathode electrode 3 is transferred to the anode electrode 2. Promotes moisture movement. Thereby, in the fuel cell 100E using the separator 15E, the occurrence of flooding is suppressed.

  FIG. 25 is an explanatory diagram for explaining improvement in power generation performance by the fuel cell 100E. FIG. 25 shows the change in cell voltage when the stoichiometric ratio of the gas supplied to the cathode electrode 3 side in the fuel cell having the same configuration as the fuel cell 100E is changed, as graph Ge of the example. Here, the “stoichiometric ratio” means the ratio between the minimum gas amount required for the power generation amount of the fuel cell and the gas amount actually supplied to the fuel cell. FIG. 25 shows a graph Gc of a comparative example in which the same measurement was performed in a fuel cell in which the heat transfer suppressing member 76 was omitted as a comparative example.

  Here, as the separator 15E of the fuel cell of the example and the comparative example, a material obtained by subjecting Cu to corrosion resistance treatment was used. In the fuel cell of the example, a polyimide film (heat transfer coefficient 0.26 W / m · K) having a thickness of 175 μm was used as the heat transfer suppressing member 76. In addition, the heat transfer suppression member 76 was arrange | positioned in the range corresponded to the range of 0-3 / 8 on the virtual number straight line NL demonstrated in FIG.

  In the measurement, each of the fuel cells of the example and the comparative example was supplied with non-humidified hydrogen at a constant flow rate on the anode electrode 2 side, and oxygen with humidity adjusted to 80% to 100% by humidification treatment on the cathode electrode 3 side. The contained gas was supplied at a constant temperature of about 60 ° C. while gradually decreasing the flow rate. During the measurement, the output current of the fuel cell was maintained at a substantially constant value. Note that the flow rate of the refrigerant supplied to the fuel cell is such that the difference between the refrigerant temperature in the refrigerant supply manifold 65 and the refrigerant temperature in the refrigerant discharge manifold 66 is substantially zero during operation of the fuel cell. It was adjusted. That is, in each single cell, the measurement was performed in a state where there was almost no difference in the cooling effect by the refrigerant between the upstream side and the downstream side of the refrigerant.

  Here, generally, the lower the stoichiometric ratio, the smaller the gas flow rate on the cathode electrode 3 side and the lowering of the drainage due to the gas flow on the cathode electrode 3 side. . That is, the higher the power generation performance in the state where the stoichiometric ratio is lower, the lower the power generation performance is reduced due to the occurrence of flooding. Therefore, it can be seen from these graphs Ge and Gc that the reduction in power generation performance due to flooding is suppressed when the heat transfer suppression member 76 is arranged in the refrigerant flow path 74.

  In addition, the hydrogen and oxygen are supplied to each of the fuel cells of the above embodiment and the comparative example without humidification, and the temperature of the refrigerant is gradually increased, so that the operation cannot be continued. The temperature was measured. Then, it was possible for the fuel cell of the example in which the heat transfer suppressing member 76 is arranged to continue power generation to a temperature higher than that of the fuel cell of the comparative example.

  Thus, according to the fuel cell 100E of the fifth embodiment, by disposing the heat transfer suppression member 76 in the refrigerant flow path 74, it is possible to suppress a decrease in power generation performance due to occurrence of flooding. Further, it is possible to improve the limit temperature at which the operation of the fuel cell 100E can be continued.

FIG. 26 is a schematic diagram showing a configuration of a fuel cell 100E ₂ as another configuration example in the fifth embodiment. FIG. 26 is substantially the same as FIG. 22 except that a second heat transfer suppressing member 77 is added on the oxygen downstream side on the cathode side. The second heat transfer suppression member 77 is preferably provided in the vicinity of the communication flow path that connects the power generation region GA and the oxygen exhaust manifold 64. Specifically, it is preferable that the second heat transfer suppressing member 77 is provided in a region in a range corresponding to a range of 4/5 to 1 on the virtual number line NL. Thereby, it is possible to suppress the exhaust of the exhaust gas from the power generation region GA on the cathode electrode 3 side from being blocked by the generated water on the cathode electrode 3 side. Therefore, the occurrence of flooding in the fuel cell 100E ₂ can be suppressed.

Thus, the fuel cell 100E of the fifth embodiment, the 100E _2, the refrigerant passage 74 of the separator 15E, by providing the heat transfer suppressing member 76 and 77, the cooling effect by the refrigerant, uneven in the manifold opposite direction It has become. As a result, the amount of moisture that moves from the cathode electrode 3 side to the anode electrode 2 side can be increased, and the blockage of the gas flow path due to the generated moisture on the cathode electrode 3 side can be suppressed, and the fuel cells 100E and 100E ₂ Reduction in power generation performance is suppressed.

F. Variation:
Note that the present invention is not limited to the above-described examples and embodiments, and can be carried out in various modes without departing from the gist thereof, and may be carried out by combining the above-described embodiments. Is possible. For example, the separator 15 of the first embodiment may be combined with the seal-integrated membrane electrode assemblies 10D _{1 to} 10D ₃ of the fourth embodiment. Further, the seal-integrated membrane electrode assembly 10D _{1 to} 10D ₃ of the fourth embodiment may be used for the fuel cell 100C of the third embodiment. Furthermore, the present invention can be implemented by the following modifications, for example.

F1. Modification 1:
In each of the above embodiments, unhumidified hydrogen and oxygen are supplied to the fuel cell 100 and the like. However, hydrogen and oxygen may be supplied after being humidified. However, as described with reference to FIGS. 7 and 8, particularly when oxygen is supplied without humidification, by providing a drying acceleration mechanism that promotes drying of the electrolyte membrane 1 on the upstream side of hydrogen, higher power generation performance is reduced. It is possible to obtain an inhibitory effect.

F2. Modification 2:
In each embodiment excluding the fifth embodiment, the gas flow path member 7 may be omitted. In this case, the flow path groove provided in the separator and the anode electrode 2 or the cathode electrode 3 may be in direct contact with each other. Even in such a configuration, the anode electrode 2 and the cathode electrode 3 can function as a gas diffusion layer, and the reaction gas can be distributed to the power generation region GA.

F3. Modification 3:
In the first embodiment, the channel cross-sectional area of the first parallel flow channel groove 21a is configured to be smaller than the flow channel cross-sectional area of the second parallel flow channel groove 21b. However, the flow path cross-sectional area of the first parallel flow path groove 21a may be the same as the flow path cross-sectional area of the second parallel flow path groove 21b or may be configured to be large. However, it is preferable to configure the flow passage cross-sectional area of the first parallel flow passage groove 21a to be smaller than the flow passage cross-sectional area of the second parallel flow passage groove 21b because the flow rate of the upstream hydrogen can be increased. .

F4. Modification 4:
In the third embodiment, the temperature control plate 210 includes the Peltier element 211 as a heating means for heating the hydrogen upstream side of the anode electrode 2. However, the temperature control plate 210 includes other heating means instead of the Peltier element 211. It is also good. For example, a heating wire or a heating plate may be arranged in the area ha.

F5. Modification 5:
In the fuel cell system 200 of the third embodiment, when the cell resistance R of at least one single cell 110 is greater than or equal to the threshold value R _upper , the control unit 250 controls all the single cells 110 by all the Peltier elements 211. On the other hand, heating / cooling processing (temperature control) was performed. However, the control unit 250 may perform temperature control by the Peltier element 211 only for the single cell 110 whose cell resistance R is _{equal to} or greater than the threshold value R _upper . That is, the control unit 250 may control the Peltier element 211 for each single cell 110.

F6. Modification 6:
In the fuel cell system 200 of the third embodiment, the control unit 250 controls the Peltier element 211 in accordance with the cell resistance R detected for each single cell 110. However, the control unit 250 may control the Peltier element 211 according to a detection value other than the cell resistance R. The controller 250 preferably controls the Peltier element 211 according to a value associated with the dryness of the membrane electrode assembly 5 in the fuel cell 100C. For example, the control unit 250 detects the cell temperature for each single cell 110 and the operation temperature of the entire fuel cell 100C, and the temperature is experimentally indicated that the dryness of the membrane electrode assembly 5 is relatively high. The driving of the Peltier element 211 may be started when the predetermined value is reached.

F7. Modification 7:
In the fourth embodiment, the anode electrode 2D of the seal-integrated membrane electrode assemblies 10D _{1 to} 10D ₃ has the first and second anode regions 2a and 2b having different water diffusion coefficients. However, the anode electrode 2D may further include a plurality of regions having different water diffusion coefficients. In the fourth embodiment, two types of catalyst inks having different mass ratios between the catalyst-carrying carbon and the electrolyte are separately applied to the two regions, whereby the first and second types having different porosity and water diffusion coefficient are used. Anode regions 2a and 2b were provided. However, the first and second anode regions 2a and 2b may be formed by different methods so that the diffusion coefficient of water is different. For example, the porosity may be changed by pressing the first and second anode regions 2a and 2b with different pressures.

F8. Modification 8:
In the fifth embodiment, the separator 15E is a two-layer separator. However, the separator 15E may be configured as a multilayer separator having a plurality of plates. For example, the heat transfer suppression members 76 and 77 described in the fifth embodiment may be disposed in the refrigerant flow path of the separator 15 of the first embodiment.

F9. Modification 9:
In the above embodiment, the refrigerant flow path is configured so that the refrigerant flows from the hydrogen upstream side toward the hydrogen downstream side when viewed in the manifold arrangement direction. May be configured to flow in the opposite flow direction.

F10. Modification 10:
In the fuel cell 100 or the like of each of the above embodiments, the hydrogen upstream side on the anode electrode 2 side is formed by the shape of the flow channel for hydrogen, the configuration of the Peltier element 211 and the anode electrode 2D, and the heat transfer suppressing members 76 and 77. The drying of the electrolyte membrane 1 was promoted. However, the fuel cell promotes drying on the upstream side of hydrogen on the anode electrode 2 side by another drying promotion mechanism, and the electrolyte membrane 1 from the oxygen downstream side on the cathode electrode 3 side to the hydrogen upstream side on the anode electrode 2 side. It is also possible to increase the amount of moisture that moves through the substrate. For example, the porosity of the gas flow path member 7 may be configured to be smaller on the hydrogen downstream side than on the hydrogen upstream side, or the area where the refrigerant flow path and the anode electrode 2 face each other may be smaller on the hydrogen upstream side. It is good to do. In addition, it is preferable that this drying promotion mechanism is provided in the range equivalent to the range of 0-1 / 2 on the virtual number line NL demonstrated in the said embodiment, and 0-3 / on the virtual number line NL. More preferably, it is provided in a range corresponding to the range of 8.

DESCRIPTION OF SYMBOLS 1 ... Electrolyte membrane 2 ... Anode electrode 2D ... Anode electrode 2a ... 1st anode area | region 2b ... 2nd anode area | region 3 ... Cathode electrode 5 ... Membrane electrode assembly 7 ... Gas flow path member 9 ... Seal part 10 ... Seal one Body type membrane electrode assembly 10D _{1 to} 10D ₃ ... Integrated seal type membrane electrode assembly (Examples 1 to 3)
10d _{1 to} 10d ₄ ... Seal-integrated membrane electrode assembly (Comparative Examples 1 to 4)
DESCRIPTION OF SYMBOLS 15 ... Separator 15E ... Separator 20 ... Anode plate 20B ... Anode plate 20C ... Anode plate 20E ... Anode plate 20a ... Anode plate 21a ... 1st parallel flow channel groove 21b ... 2nd parallel flow channel groove 22a ... 1st connection Channel groove 22b ... Second connection channel groove 23a ... First manifold communication channel groove 23b ... Second manifold communication channel groove 24 ... Parallel channel grooves 25a, 25b ... Through holes 26, 27 ... Partition 30 ... Cathode plate 30C ... Cathode plate 30E ... Cathode plate 31 ... Parallel flow channel 32a ... First connection channel groove 32b ... Second connection channel groove 33a ... First manifold communication channel groove 33b ... Second manifold communication channel groove 35a, 35b ... through hole 40 ... intermediate plate 42 ... hollow portion 43 ... flow Wall 44a ... Hydrogen supply flow channel 44b ... Hydrogen discharge flow channel 45a ... Oxygen supply flow channel 45b ... Oxygen discharge flow channel 61 ... Hydrogen supply manifold 62 ... Hydrogen discharge manifold 63 ... Oxygen supply Manifold 64 ... Oxygen discharge manifold 65 ... Refrigerant supply manifold 66 ... Refrigerant discharge manifold 71 ... Hydrogen flow path 72 ... Oxygen flow path 74 ... Refrigerant flow path 76 ... Heat transfer suppression member 77 ... Second heat transfer suppression member 100 ... Fuel cell 100B ... Fuel cell 100C ... Fuel cell 100E, 100E ₂ ... Fuel cell 100a ... Fuel cell 110 ... Single cell 200 ... Fuel cell system 201 ... First surface 202 ... Second surface 210 ... Temperature control plate 211 ... Peltier element 220 ... Peltier element control unit 230 ... External storage battery 240 ... Cell resistance monitor 250 ... Control Department NL ... the number of virtual straight line ha ... area

Claims (19)

A fuel cell that generates electricity using an electrochemical reaction between a fuel gas and an oxidant gas,
A membrane electrode assembly having a power generation region in which an anode electrode and a cathode electrode are respectively disposed on both surfaces of the electrolyte membrane;
An anode separator and a cathode separator that sandwich the membrane electrode assembly;
With
Between the anode separator and the electrolyte membrane, an anode flow for flowing the fuel gas from a first end of the power generation region toward a second end opposite to the first end. There is a road,
Between the cathode separator and the electrolyte membrane, a cathode flow path for flowing the oxidant gas from the first end toward the second end is provided,
The anode upstream side portion closer to the first end portion of the anode channel promotes drying of the electrolyte membrane on the anode electrode side, and the first end portion of the cathode channel is promoted. A fuel cell is provided with a drying acceleration mechanism for increasing the amount of water that moves through the electrolyte membrane from the cathode downstream portion closer to the anode upstream portion. The fuel cell according to claim 1, wherein
The anode flow path includes an anode flow path groove provided on a surface of the anode separator on the anode electrode side, and a gas diffusion layer disposed between the anode flow path groove and the anode electrode,
The fuel cell includes a fuel gas supply manifold provided at a position outside the first end portion side of the power generation region, and a fuel provided at a position outside the second end portion side of the power generation region. A gas exhaust manifold,
The anode channel groove includes a supply side anode channel groove connected to the fuel gas supply manifold, and a discharge side anode channel groove connected to the fuel gas discharge manifold,
The discharge-side anode flow channel groove has a discharge-side power generation region flow channel groove extending from the first end side to the second end side in the power generation region,
Between the supply side anode flow channel and the discharge side anode flow channel, a flow channel partition for separating the supply side anode flow channel and the discharge side anode flow channel is provided. And
The fuel gas flowing through the supply-side anode flow channel is guided into the gas diffusion layer by the flow channel partition wall, is humidified in the gas diffusion layer, and then into the discharge-side anode flow channel. Flowing fuel cell. The fuel cell according to claim 2, wherein
The supply-side anode channel groove has a supply-side power generation region channel groove extending from the first end side to the second end side in the power generation region,
The supply-side power generation region flow channel groove and the discharge-side power generation region flow channel groove are provided so as to run side by side across the flow channel groove partition wall,
The fuel cell, wherein a flow path cross-sectional area of the supply side power generation region flow channel is smaller than a flow path cross sectional area of the discharge side power generation region flow channel. The fuel cell according to claim 3, wherein
The anode flow path is configured such that the flow rate of the fuel gas increases toward the upstream side within a range of ½ of the upstream side of the entire range from the first end to the second end. A fuel cell. The fuel cell according to claim 4, wherein
The anode flow path is configured such that the flow rate of the fuel gas increases toward the upstream side within a range of 3/8 on the upstream side of the entire range from the first end to the second end. A fuel cell. The fuel cell according to any one of claims 1 to 5, further comprising:
On the outside of the anode plate, a coolant channel that runs parallel to the anode channel is provided,
Heat transfer suppression for suppressing heat transfer from the anode channel to the refrigerant in the refrigerant channel on the channel wall surface on the anode plate side in the refrigerant channel adjacent to the anode upstream side part A fuel cell in which members are disposed. The fuel cell according to claim 6, wherein
The heat transfer suppressing member is a fuel cell provided in a range of ½ of the upstream side of the entire range from the first end to the second end. The fuel cell according to claim 7, wherein
The heat transfer suppressing member is a fuel cell provided in an upstream 3/8 of the entire range from the first end to the second end. A fuel cell according to any one of claims 1 to 8,
The anode electrode has two or more regions having different water diffusion coefficients such that the water diffusion coefficient upstream of the anode flow path is higher than the water diffusion coefficient downstream of the anode flow path. A fuel cell is provided. The fuel cell according to claim 9, wherein
The anode electrode has a first anode region and a second anode region having a water diffusion coefficient smaller than the first anode region;
The first anode region is provided within a range of 3/8 on the upstream side of the entire range from the first end to the second end,
The second anode region is provided so as to include the entire region downstream from the upstream 3/8 range of the entire range from the first end to the second end. ,Fuel cell. The fuel cell according to claim 10, wherein
The first anode region is provided in a range of 1/8 to 3/8 on the upstream side of the entire range from the first end to the second end,
The fuel cell, wherein the second anode region is provided in a region excluding the first anode region. A fuel cell according to any one of claims 9 to 11, comprising:
The fuel cell, wherein the two or more regions having different water diffusion coefficients are regions having different porosity. A fuel cell according to any one of claims 9 to 12,
The anode electrode includes an electrolyte and catalyst-supported carbon on which a catalyst for promoting a power generation reaction is supported,
The fuel cell, wherein a diffusion coefficient of water in the anode electrode is set to a different value by changing a mass of the catalyst-supporting carbon with respect to a mass of the electrolyte contained in the anode electrode. The fuel cell according to any one of claims 1 to 13, further comprising:
A fuel cell, wherein a heating unit for heating the upstream side of the anode flow path is provided outside the anode plate. 15. The fuel cell according to claim 14, wherein
The heating unit is arranged so as to heat a region on the anode electrode within a range of 1/2 of the upstream side of the entire range from the first end to the second end. A fuel cell. The fuel cell according to claim 15, wherein
The heating unit is arranged to heat a region on the anode electrode within a range of 3/8 on the upstream side of the entire range from the first end to the second end. A fuel cell. A fuel cell system,
A fuel cell according to any one of claims 14 to 16, and
A dryness detection unit for detecting a value associated with the dryness of the electrolyte membrane;
A control unit for controlling the driving state of the heating unit;
With
The fuel cell includes a fuel cell stack in which a plurality of power generation modules having the membrane electrode assembly sandwiched between the anode separator and the cathode separator are stacked,
The heating unit includes first and second surfaces, and includes a Peltier element capable of heating the first surface side and cooling the second surface side,
The heating unit is disposed between each of the plurality of power generation modules such that the first surface faces the anode separator and the second surface faces the cathode separator,
The control unit drives the Peltier element when the detection value of the dryness detection unit is greater than or equal to a threshold value, and promotes vaporization of moisture in the anode upstream portion of each of the plurality of power generation modules. A fuel cell system that promotes liquefaction of moisture in the cathode downstream portion and increases the amount of moisture that moves from the cathode downstream portion to the anode upstream portion via the electrolyte membrane. The fuel cell according to any one of claims 1 to 16, comprising:
The drying promotion mechanism is a fuel cell provided in a range of ½ of the upstream side of the entire range from the first end to the second end. The fuel cell according to claim 18, wherein
The drying promotion mechanism is a fuel cell provided in an upstream 3/8 of the entire range from the first end to the second end.

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