WO2006134867A1

WO2006134867A1 - Fuel cell

Info

Publication number: WO2006134867A1
Application number: PCT/JP2006/311743
Authority: WO
Inventors: Shinsuke Takeguchi; Kazuhito Hatoh; Hiroki Kusakabe; Yasuo Takebe
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2005-06-13
Filing date: 2006-06-12
Publication date: 2006-12-21

Abstract

A highly reliable polyelectrolyte fuel cell exhibiting excellent durability and heat recovery power by enhancing cooling effect more on the inlet side than on the outlet side of at least one of a fuel gas channel and an oxidizing agent gas channel without lowering the total cooling efficiency by cooling fluid. At least one of an anode side separator and a cathode side separator is provided with a cooling fluid channel constituted of two or more grooves. While gradually widening the interval between grooves from one inlet toward the outlet of at least one of the fuel gas channel and the oxidizing agent gas channel, the number of grooves is kept constant and the widths of two or more grooves are kept constant from the inlet to the outlet.

Description

Specification

Fuel cell

Technical field

The present invention relates to a fuel cell used for a portable power source, a power source for electric vehicles, a domestic cogeneration system, and the like.

Background art

[0002] A conventional polymer electrolyte fuel cell using a polymer electrolyte having positive ion (hydrogen ion) conductivity electrically connects a fuel gas containing hydrogen and an oxidant gas containing oxygen such as air. By making it react chemically, electric power and heat are generated simultaneously. FIG. 8 is a schematic cross-sectional view showing an example of a basic configuration of a membrane electrode assembly (MEA) included in a unit cell mounted on a conventional polymer electrolyte fuel cell. FIG. 9 is a schematic cross-sectional view showing an example of the basic configuration of a unit cell using the membrane electrode assembly shown in FIG.

As shown in FIG. 8, in a membrane electrode assembly 200 of a conventional polymer electrolyte fuel cell, an electrode catalyst (for example, platinum) is formed on both sides of a polymer electrolyte membrane 201 that selectively transports hydrogen ions. Catalyst layers 202a and 202b made of a mixture of a catalyst body made of carbon powder supporting (metal) and a polymer electrolyte having hydrogen ion conductivity are formed.

Gas diffusion layers 203a and 203b are disposed outside the catalyst layers 202a and 202b. The catalyst layer 202a and the gas diffusion layer 203a constitute an anode 204a, and the catalyst layer 202b and the gas diffusion layer 203b are in force. Sword 204b is configured. Then, the catalyst layer 202a of the anode 204a, equation (1): H → reaction protons caused by represented by 2H ⁺ + 2e ", the force Sword 204b touch

2

In the medium layer 202b, oxygen and protons that have moved from the anode 204a and force (2): lZ20

2

Water is produced by the reaction represented by + 2H ⁺⁺ 2e "→ HO.

2

As shown in FIG. 9, in the unit cell 210 using the MEA 200 shown in FIG. 8, the leakage of fuel gas and oxidant gas supplied to the anode 204a and the power sword 204b to the outside is prevented. Gaskets 206a and 206b are disposed around the anode 204a and the force sword 204b with the polymer electrolyte membrane 201 interposed therebetween to prevent mixing of various types of gases. Gaskets 206a and 206b are composed of anode 204a, force sword 204b, A structure obtained by assembling together with the subelectrolyte membrane 201 and combining them together may be referred to as MEA.

In addition, the unit cell 210 includes conductive plate-like separators 205a and 205b for mechanically fixing and electrically connecting adjacent unit cells. Then, the reaction gas (fuel gas or oxidant gas) is supplied to the anode 204a or the power sword 204b to the part where the separators 205a and 205b are in contact with the anode 204a and the power sword 204b, respectively. Gas flow paths 207a and 207b for carrying away excess gas are formed.

[0006] Further, since the MEA 200 generates heat when power generation is performed, in order to maintain the temperature of the MEA 200 at an allowable operating temperature, a surplus heat is removed by circulating a cooling fluid such as cooling water. Generally, in at least one of the separator 205a and the separator 205b, cooling water passages 208a and 208b are provided on the surface opposite to the surface on which the gas passages 207a and 207b are formed, and a cooling fluid such as cooling water is provided here. Is distributed.

[0007] The cooling water channels 208a and 208b include a plurality of linear grooves, a turn-shaped groove that connects the ends of the adjacent linear grooves from the upstream side to the downstream side, and a powerful serpentine type A cooling water flow path is often used, and the grooves are generally formed at equal intervals. The cooling water channels 208a and 208b may be constituted by a plurality of substantially parallel linear grooves, but in this case as well, the grooves are generally formed at equal intervals.

[0008] Here, in the plane of the unit cell 210 as described above, power generation and heat generation are collected at the inlet portion of the supplied fuel gas or oxidizing agent gas, that is, upstream of the gas flow paths 207a and 207b. As a result, there is a problem that the temperature of the MEA 200 and the separators 205a and 205b corresponding to the inlet portion increases. From the viewpoint of durability of the polymer electrolyte fuel cell, the cell performance is improved by setting the relative humidity of the reaction gas at the electrode (anode and force sword) part to 100% or more, that is, oversaturated over the entire area. It is known that the deterioration of is suppressed.

[0009] Therefore, for example, in Patent Document 1! /, An effort was made to improve battery performance by devising the configuration of the cooling water flow path and controlling the temperature gradient in the plane of the unit cell. It has been broken.

Specifically, the cooling capacity of the cooling fluid is determined by the flow path for oxidant gas and Z or fuel gas. It is configured so that the outlet side is lower than the inlet side of the flow path, and more heat is removed in the region on the inlet side where the calorific value is excessive, and saturation occurs due to the temperature rise of the reaction gas on the outlet side. Methods have been proposed that are intended to increase the water vapor and increase the water discharge.

Patent Document 1: Japanese Patent Laid-Open No. 2004-39540

Disclosure of the invention

Problems to be solved by the invention

[0010] However, in the method described in Patent Document 1, the cooling effect on the inlet side is higher than that on the outlet side of the fuel gas flow path and the Z or oxidant gas flow path. Although it is possible to form a predetermined temperature distribution with this, the cooling efficiency of the cooling fluid on the outlet side will be reduced, but the cooling efficiency will be reduced as a whole. .

[0011] Further, in the invention described in Patent Document 1, the number of rib portions separating the grooves is reduced in the downstream region of the cooling water flow path of the separator where the cooling capacity is reduced. The number of grooves is reduced, and the width of the grooves {that is, the pitch between the channels} is extremely wide. For this reason, the cross-sectional area of the cooling water flow path on the downstream side increases, the speed at which the cooling water flows per unit area on the downstream side or the outlet side decreases, and the heat exchange amount to the cooling water decreases. Therefore, it is necessary to flow excess cooling water in order to achieve a predetermined amount of heat removal in the plane of the cell, and the work of the pump that supplies the cooling water increases, and the fuel cell is systemized. Another problem is that it reduces the overall efficiency of the entire system.

[0012] Furthermore, as described above, in the separator described in Patent Document 1, the number of grooves is reduced by reducing the number of rib portions separating the grooves in the downstream region. Therefore, it is inferior in mechanical strength, and when a single cell using the separator is laminated and a stack for a fuel cell is manufactured and fastened, there is a concern that the separator may be cracked or cracked due to mechanical fatigue. There is also a problem that the contact area between the separator and the anode or the force sword is small and the efficiency is lowered due to an increase in electrical resistance.

[0013] Therefore, the present invention has been made in view of the above problems, and is applied to the entire fuel cell. Without reducing the cooling efficiency due to the cooling fluid, the cooling effect on the inlet side of the flow path for fuel gas and the flow path for oxidant gas is higher than that on the outlet side. Since the temperature distribution can be realized and the cooling efficiency is increased, it becomes unnecessary to supply the cooling water unnecessarily, so that the cooling fluid can be circulated without increasing the power consumption of the pump. It is an object of the present invention to provide a highly reliable polymer electrolyte fuel cell with excellent durability and heat recovery capability, which is less prone to cracks and cracks due to mechanical fatigue and increases in electrical resistance. Furthermore, another object of the present invention is to provide a cell router capable of easily and surely realizing the polymer electrolyte fuel cell as described above.

Means for solving the problem

[0014] The present inventors diligently studied to achieve the above-described object, and as a result, the cooling fluid channel is composed of two or more grooves, and the fuel gas channel and the oxidant gas channel. The gap between the grooves constituting the cooling fluid flow path is widened from at least one of the inlets to the outlet, and the number of grooves is the same from the inlet to the outlet. The present inventors have found that the above-described problems can be solved by adopting a configuration in which the widths of the grooves equal to or larger than the above are constant from the above-mentioned inlet to the outlet, and the present invention has been completed.

[0015] That is, the inventor who should solve the above problems

Conductive anode side including a polymer electrolyte membrane having hydrogen ion conductivity, an anode and a force sword sandwiching the polymer electrolyte membrane, and a fuel gas passage for supplying and discharging fuel gas to and from the anode A unit cell comprising a separator and a conductive power sword side separator including a flow path for an oxidant gas for supplying and discharging an oxidant gas to the power sword;

A cooling fluid flow path including at least one groove of at least one of the anode side separator and the force sword side separator;

On the main surface of the anode side separator and the force sword side separator on which the cooling fluid flow path is formed, the distance between adjacent grooves of the two or more grooves is determined by the fuel gas flow path and the oxidation flow path. The force S that extends from at least one of the agent gas flow paths to the outlet spreads, and the number of two or more grooves is the same from the inlet to the outlet. Provided is a fuel cell characterized in that the width of each of the two or more grooves is constant up to the inlet force and the outlet.

[0016] By adopting the configuration as described above, the cooling efficiency by the cooling fluid in the entire fuel cell is not lowered, and the outlet side of at least one of the fuel gas channel and the oxidant gas channel is reduced. It is possible to increase the cooling effect on the inlet side to realize a preferable temperature distribution in the plane of the unit cell, and to realize such a preferable temperature distribution without increasing the pressure loss. Cooling fluid can be circulated without reducing the volume (pump efficiency), and it is difficult to cause cracks and cracks due to mechanical fatigue of the separator and increase in electrical resistance.Excellent durability and heat recovery In addition, a highly reliable polymer electrolyte fuel cell can be provided.

[0017] It should be noted that the configuration of the present invention as described above is neither disclosed nor suggested in Patent Document 1, and depending on the configuration described in Patent Document 1, a fuel gas flow path and an oxidant gas are used. Although it is possible to increase the cooling effect at the inlet rather than the outlet of the flow path to form a temperature distribution in the plane of the unit cell, the cooling efficiency of the entire fuel cell is reduced, the pressure loss is increased, the work load ( It has been difficult to reduce the pump efficiency) and to prevent the separator from cracking, cracking and electrical resistance. In particular, assuming that a polymer electrolyte fuel cell is used in an on-site type cogeneration system, from the viewpoint of heat recovery becoming a very important factor, the high power described in Patent Document 1 is described. The molecular electrolyte fuel cell has a problem.

[0018] The present invention eliminates such a conventional problem and reduces at least one of the fuel gas flow path and the oxidant gas flow path without reducing the cooling efficiency by the cooling fluid in the entire fuel cell. In order to realize such a suitable temperature distribution without increasing the pressure loss, the cooling effect on the inlet side can be enhanced rather than the outlet side of the cell, and a suitable temperature distribution can be realized in the plane of the unit cell. In addition, the cooling fluid can be circulated without reducing the amount of work (pump efficiency), and it is difficult for cracks and cracks to occur due to mechanical fatigue of the separator and increase in electrical resistance! An object of the present invention is to provide a highly reliable polymer electrolyte fuel cell with excellent heat recovery capability.

Furthermore, the present invention reduces the cooling efficiency by the cooling fluid in the entire fuel cell. In addition, the cooling effect on the inlet side of the fuel gas channel and the oxidant gas channel can be enhanced more than the outlet side of the fuel gas channel and the oxidant gas channel, and a suitable temperature distribution can be realized in the plane of the unit cell. In order to realize such a suitable temperature distribution without increasing the pressure loss, it is possible to circulate the cooling fluid without reducing the work (pump efficiency), and it has excellent durability and heat recovery capability. It is an object of the present invention to provide a separator that can easily and reliably realize a polymer electrolyte fuel cell that does not easily cause cracks due to mechanical fatigue, generation of cracks, or increase in electrical resistance. .

The invention's effect

[0020] According to the present invention, by adopting the above-described configuration, at least one of the fuel gas channel and the oxidant gas channel without reducing the cooling efficiency by the cooling fluid in the entire fuel cell. The cooling effect on the inlet side can be enhanced rather than one outlet side to achieve a suitable temperature distribution in the plane of the unit cell, and such a suitable temperature distribution can be realized without increasing the pressure loss. Therefore, the cooling fluid can be circulated without reducing the work volume (pump efficiency), and it is difficult to cause cracks and cracks due to mechanical fatigue of the separator and increase in electrical resistance, durability and heat recovery. A polymer electrolyte fuel cell with excellent performance can be provided. Furthermore, according to the present invention, it is possible to easily and reliably realize the polymer electrolyte fuel cell as described above, and it is difficult to cause cracks or cracks due to mechanical fatigue or increase in electrical resistance. A separator can be provided.

Brief Description of Drawings

FIG. 1 is a schematic cross-sectional view showing an example of the basic configuration of a membrane electrode assembly (MEA) included in a unit cell mounted on a polymer electrolyte fuel cell of the present invention.

2 is a schematic cross-sectional view showing an example of a basic configuration of a unit cell using the membrane electrode assembly shown in FIG.

3 is a front view of the separator 5a on the anode 4a side in the unit cell 110 shown in FIG. 2 as viewed from the cooling fluid flow path 8a side.

4 is a rear view of the separator 5a on the anode 4a side in the unit cell 110 shown in FIG. 3, that is, a front view seen from the fuel gas flow path 7a side.

[Fig.5] Power sword in unit cell 110 shown in Fig. 2 Separator 5b for cooling fluid 5b It is the front view seen from the flow path 8b side.

6 is a rear view of the separator 5b on the side of the force sword 4b in the unit cell 110 shown in FIG. 5, that is, a front view of the side force of the oxidizing gas channel 7b.

FIG. 7 is a front view of the separator 4a on the anode 4a side used in the comparative example of the present invention as viewed from the cooling fluid channel 8a side.

FIG. 8 is a schematic cross-sectional view showing an example of a basic configuration of a membrane electrode assembly (MEA) included in a unit cell mounted on a conventional polymer electrolyte fuel cell.

FIG. 9 is a schematic cross-sectional view showing an example of the basic configuration of a unit cell using the membrane electrode assembly shown in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions may be omitted.

FIG. 1 is a schematic cross-sectional view showing an example of a basic configuration of a membrane electrode assembly (MEA) included in a unit cell mounted on a polymer electrolyte fuel cell of the present invention. FIG. 2 is a schematic cross-sectional view showing an example of the basic configuration of a unit cell using the membrane electrode assembly shown in FIG.

[0023] As shown in FIG. 1, in the polymer electrolyte fuel cell MEA100 of the present invention, a polymer electrolyte membrane that selectively transports hydrogen ions (for example, Naf ion (trade name, manufactured by DuPont, USA) )) On both sides of 1, catalyst layers 2a and 2b are formed which are a mixture force of conductive carbon particles carrying an electrode catalyst (for example, a noble metal such as platinum) and a polymer electrolyte having hydrogen ion conductivity.

The catalyst layers 2a and 2b are formed by a method known in the art using a catalyst layer forming ink containing conductive carbon particles supporting a noble metal electrode catalyst, a high molecular electrolyte, and a dispersion medium. can do.

[0024] Gas diffusion layers 3a and 3b are disposed outside the catalyst layers 2a and 2b. The catalyst layer 2a and the gas diffusion layer 3a constitute an anode 4a. The catalyst layer 2b and the gas diffusion layer 3b Constitutes power sword 4b. The material constituting the gas diffusion layers 3a and 3b is not particularly limited, and those known in the art can be used. For example, carbon cloth and carbon paper One such conductive porous substrate can be used. The conductive porous substrate may be subjected to a water repellent treatment by a conventionally known method.

Furthermore, the MEA 100 can also be produced from the polymer electrolyte membrane 1, the catalyst layers 2a and 2b, and the gas diffusion layers 3a and 3b as described above by techniques known in the art.

Next, as shown in FIG. 2, in the unit cell 110 using the MEA 100 shown in FIG. 1, the fuel gas and the oxidant gas supplied to the anode 4 a and the power sword 4 b are prevented from leaking to the outside. In order to prevent mixing of the two kinds of gases, gaskets 6a and 6b are disposed around the anode 4a and the force sword 4b with the polymer electrolyte membrane 1 interposed therebetween. Conventionally known gaskets can be used as the gaskets 6a and 6b.

[0026] The polymer electrolyte fuel cell of the present invention comprises one or more unit cells 110 as described above. On both sides of the unit cell 110, conductive plate-like separators 5a and 5b are arranged. Then, the reaction gas (fuel gas or oxidant gas) is supplied to the anode 4a or the power sword 4b to the part where the separators 5a and 5b are in contact with the anode 4a and the power sword 4b, respectively, and the generated gas and surplus gas are carried away. Gas flow paths 7a and 7b for the purpose are formed. Such separators 5a and 5b mechanically fix and electrically connect adjacent unit cells when two or more unit cells 110 are stacked and used.

[0027] Further, when power is generated in the polymer electrolyte fuel cell, the MEA 100 generates heat. Therefore, in order to maintain the temperature of the MEA 100 at an allowable operating temperature, a surplus heat is generated by circulating a cooling fluid such as cooling water. Is removed, that is, heat recovery is performed. Therefore, in both the separators 5a and 5b in the present embodiment, the cooling water flow paths 8a and 8b are provided on the surface opposite to the surface where the gas flow paths 7a and 7b are formed. The cooling fluid is circulated.

In FIG. 2, the cooling fluid channels 8a and 8b are formed on both sides of the unit cell 110. However, when two or more unit cells 110 are stacked and used as a stack, the unit cells 2 to A cooling fluid flow path may be arranged for every three. When a cooling fluid flow path is not formed between the cells, a fuel gas flow path is provided on one side and an oxidant gas flow path is provided on the other side. It is also possible to use a single separator that also serves as the sword side separator plate. [0029] In addition, as a material of the separator plate, there are a metal, a carbon, a material excellent in thermal conductivity and conductivity obtained by mixing graphite and resin, and these can be widely used. For example, a separator plate obtained by injection molding a mixture of carbon powder and a binder, or a titanium or stainless steel separator plate whose surface is gold-plated can also be used.

[0030] Here, as described above, in the conventional polymer electrolyte fuel cell, the fuel gas flow path and the oxidant gas are caused by the shape of the cooling fluid flow path in the separator. Although it is possible to increase the cooling effect at the inlet rather than the outlet of the service flow path and form a temperature distribution in the plane of the unit cell, the cooling efficiency of the entire fuel cell is reduced and the work (pump efficiency) is reduced. In addition, there were problems such as cracking of the separator, generation of cracks, and increase in electrical resistance. In the present invention, in order to solve the problem, a cooling fluid passage having a shape different from the conventional one is used, and a separator having a completely new structure is used.

[0031] In the following, a separator (an embodiment of the separator of the present invention) used for 110 cells of the unit cell mounted on the polymer electrolyte fuel cell of the present invention will be described in more detail with reference to the drawings.

FIG. 3 is a front view of the separator 5a on the anode 4a side of the unit cell 110 shown in FIG. 2 as viewed from the cooling fluid flow path 8a side. FIG. 4 is a rear view of the separator 5a on the anode 4a side in the unit cell 110 shown in FIG. 3, that is, a front view of the fuel gas channel 7a side force.

[0032] As shown in Figs. 3 and 4, the separator 5a on the anode 4a side includes an oxidant gas inlet-side manifold hole 11, an oxidant gas outlet-side manifold hole 12, and a fuel gas inlet. It has a side hold hole 9 and a fuel gas outlet side hold hole 10, a cooling fluid inlet side hold hole 13, and a cooling fluid outlet side hold hole 14.

The separator 5a has a fuel gas flow path 7a for connecting the fuel gas hold holes 9 and 10 on the surface facing the anode 4a, and the cooling fluid merge holes 13 and 1 on the back surface. 4 has a cooling fluid flow path 8a connecting the four.

3 and 4, the region surrounded by the broken line 15 corresponds to the region where the power generation unit including the anode 4a of the MEA 100 is located. As shown in FIG. 3, the cooling fluid channel 8a has a so-called serpentine shape. More specifically, the cooling fluid flow path 8a is constituted by two parallel grooves, and in the area surrounded by the broken line 15, each groove is adjacent to 14 horizontal portions extending in the horizontal direction. There are also six turn sections and force to connect the straight sections to form a single serpentine groove. The number of grooves and the number of turn portions are not limited to these, and can be appropriately set within a range not impairing the effects of the present invention.

[0034] Here, the two parallel grooves constituting the cooling fluid flow path 8a have an interval between the grooves that is approximately the inlet of the fuel gas flow path 7a (the fuel gas inlet side mask). -As it goes from the hold hole 9) to the outlet (fuel gas outlet side hold hole 10), that is, with the force S passing through the turn part, the width increases and the number of grooves reaches the above inlet It is configured to be the same. Further, the width of each groove constituting the cooling fluid channel 8a is constant from the inlet to the outlet.

More specifically, as shown in FIG. 3, on the main surface of the separator 5a where the cooling fluid flow path 8a is formed, the horizontal direction of the grooves 8a and 8a (in this embodiment, Separator

1 2

On the main surface F5a on the side where the cooling fluid flow path 8a is formed on 5a, assuming the XY Cartesian coordinates, the direction is substantially parallel to the X-axis direction and is a straight portion of the groove 8a and the groove 8a. Almost flat

1 2

And the vertical direction between the groove 8a and the groove 8a (in this embodiment, a 1 2

In this case, on the main surface F5a of the separator 5a on the side where the cooling fluid flow path 8a is formed, assuming an XY orthogonal coordinate, the direction is substantially parallel to the Y-axis direction, and the groove 8a

1 and groove

Distance in the direction that is substantially parallel to the turn part of 8a V force Cooling fluid channel 8a inlet (

2 a

The groove 8a expands as it goes from the inlet side hold hole 13) of the cooling fluid to the outlet (outlet side hold hole 14 of the cooling fluid), that is, through the turn portion. Dimensionally spread. The number of grooves 8a is the same from the inlet to the outlet, and the width of each of the grooves 8a and 8a is the same from the inlet to the outlet.

1 2

It is constant.

[0036] Thus, when the cooling fluid flow path 8a is serpentine, the flow of the grooves 8a and 8a

1 2 The path lengths can be made almost the same, so the pressure loss difference between groove 8a and groove 8a

1 2

Can be reduced and increase the distribution of cooling fluid closer to a uniform state Can do. In addition, since the channel length of the cooling fluid channel can be shortened without reducing the cooling efficiency, the pressure loss can be reduced, and the reduction in system efficiency can be suppressed. That is, in this embodiment, the plurality of grooves 8a, 8a force

1 2

Are connected to the hole 13 and the outlet-side hold hole 14 and spread two-dimensionally on the separator 5a as described above, and the width of each of the grooves 8a and 8a is the same as that of the inlet.

1 2

By being constant from the side to the outlet side, it is possible to obtain the effects of reducing the pressure loss of the cooling fluid flow path and suppressing the reduction of the system efficiency as compared with the prior art.

[0037] Further, the fuel gas flow path 7a also has two parallel groove forces, and in the region surrounded by the broken line 15, each groove is adjacent to 22 horizontal portions extending in the horizontal direction. It consists of 10 turn sections that connect the straight sections. The number of grooves and the number of turn portions are not limited to these, and can be appropriately set within a range not impairing the effects of the present invention.

On the other hand, FIG. 5 is a front view of the separator 5b on the force sword 4b side of the unit cell 110 shown in FIG. 2 as viewed from the cooling fluid flow path 8b side. FIG. 6 is a rear view of the separator 5b on the side of the force sword 4b in the unit cell 110 shown in FIG. 5, that is, a front view of the oxidant gas channel 7b side force.

As shown in FIG. 5 and FIG. 6, the separator 5b on the side of the force sword 4b includes an oxidant gas inlet-side hold hole 11, an oxidant gas outlet-side hold hole 12, and a fuel gas inlet-side hold. -It has a hold hole 9, a fuel gas outlet side hold hole 10, a cooling fluid inlet side hold hole 13, and a cooling fluid outlet side hold hole 14.

Further, the separator 5b has an oxidant gas flow path 7b connecting the oxidant gas merge holes 11 and 12 on the surface facing the force sword 4b, and a cooling fluid hold on the back surface. A cooling fluid flow path 8b connecting the holes 13 and 14 is provided.

5 and 6, the region surrounded by the broken line 15 corresponds to the region where the power generation unit including the force sword 4b of the MEA 100 is located.

As shown in FIG. 5, the cooling fluid channel 8b has a so-called serpentine shape. More specifically, the cooling fluid flow path 8b is composed of two parallel grooves, and in the region surrounded by the broken line 15, each groove has 14 straight portions extending in the horizontal direction and adjacent straight lines. 6 pieces to connect the parts to form a single serpentine groove It consists of a turn part and a force. The number of grooves and the number of turn portions are not limited to these, and can be appropriately set within a range not impairing the effects of the present invention.

[0040] Here, the two parallel grooves constituting the cooling fluid flow path 8b are such that the distance between the grooves is substantially the inlet of the oxidizing gas flow path 7b (oxidant gas inlet). From the side hold hole 11) to the exit (oxidant gas outlet side hold hole 12), that is, as it passes through the turn portion, and the number of grooves increases from the above-mentioned entrance to the exit. Up to the same. The width of each groove constituting the cooling fluid flow path b is constant from the inlet to the outlet.

More specifically, as shown in FIG. 5, the horizontal direction of the groove 8b and the groove 8b (in this embodiment,

1 2

On the main surface F5b of the separator 5b on the side where the cooling fluid flow path 8b is formed, assuming an XY orthogonal coordinate, the direction is substantially parallel to the X-axis direction, and the grooves 8b and Groove 8b

1 in a direction substantially parallel to the straight line portion 1) and the vertical direction of the grooves 8b and 8b.

2 b 1 2

Direction (in this embodiment, on the main surface F5b of the separator 5b on the side where the cooling fluid flow path 8b is formed, assuming XY orthogonal coordinates, the direction is substantially parallel to the Y-axis direction. , Groove 8b and spacing in the direction substantially parallel to the turn part of groove 8b) V 1S cooling flow

1 2 b

The body channel 8b becomes wider as it goes from the inlet (cooling fluid inlet-side manifold hole 13) to the outlet (cooling fluid outlet-side manifold hole 14), that is, through the turn section. The groove 8b extends two-dimensionally on the separator 5b. The number of grooves 8b is the same from the inlet to the outlet, and the width of each of the grooves 8b and 8b is

1 2

It is constant from the entrance to the exit.

[0042] As described above, when the cooling fluid flow path 8b has a serpentine shape, the flow of the grooves 8b and 8b

1 2 The path length can be almost matched, so the pressure loss difference between groove 8b and groove 8b

1 2

And the distribution of the cooling fluid can be improved to be closer to a uniform state. Further, since the flow path length of the cooling fluid flow path can be shortened without reducing the cooling efficiency, the pressure loss can be reduced, and the reduction in system efficiency can be suppressed. , Multiple grooves 8b, 8b force

1 2

Connected to the hole 13 and the outlet hold hole 14 and on the separator 5b as described above. And the width of each of the grooves 8b and 8b is

1 2

[0043] Further, the oxidant gas flow path 7b also has two parallel groove forces, and in the region surrounded by the broken line 15, each groove has 22 straight portions extending in the horizontal direction and adjacent straight lines. It consists of 10 turn parts that connect the parts. The number of grooves and the number of turn portions are not limited to these, and can be appropriately set within a range not impairing the effects of the present invention.

[0044] As described above, in the separators 5a and 5b according to the present embodiment, the number of grooves constituting the cooling fluid channels 8a and 8b is set to the inlet of the fuel gas channel 7a (the inlet of the fuel gas). As the side-male hole 9) also goes to the outlet (fuel gas outlet-side hold hole 10), the inlet of the oxidant gas flow path 7b (oxidant gas inlet-side hold hole 10) 11) The force is the same as it goes to the outlet (oxidant gas outlet side hold hole 12), and the gap between the grooves gradually increases.

[0045] By having such a configuration, the reaction gas flow path inlets in the separators 5a and 5b in the present invention (the fuel gas inlet side hold hole 9 and the oxidant gas inlet side hold hole) On the 11) side, that is, on the upstream side, the amount of cooling fluid contributing to heat exchange increases per unit volume of the separators 5a and 5b. On the other hand, on the outlet side of the reaction gas flow path in the separators 5a and 5b (the fuel gas outlet side hold hole 10 and the oxidant gas outlet side hold hole 12), that is, on the downstream side, the separator 5a The amount of cooling fluid that contributes to heat exchange is reduced per unit volume of 5b. Therefore, a higher cooling effect can be exhibited on the upstream side where more heat is generated. Further, since the groove shapes of the cooling fluid flow paths 8a and 8b are the same in the plane of the separators 5a and 5b, the cooling capacity of the cooling fluid itself is not lowered.

[0046] In addition, by using a material having excellent thermal conductivity as the separators 5a and 5b, the outlet of the reaction gas channel (the fuel gas outlet side manifold hole 10 and the oxidant gas outlet side matrix). -Even if the gap between the grooves is widened on the hold hole 12) side, that is, on the downstream side, the temperature distribution in the separators 5a and 5b hardly occurs. Or, the generated temperature distribution tends to disappear.

Furthermore, in order not to change the number of grooves constituting the cooling fluid channels 8a and 8b, If the number is increased, there will be no problem with lowering the distribution of the cooling fluid.

[0047] It should be noted that the polymer electrolyte fuel cell of the present invention has a cooling fluid channel and a separator as compared with a conventional cooling fluid channel comprising a plurality of grooves formed at equal intervals. However, the total length of the cooling fluid flow path is shortened, and there is an advantage that pressure loss is reduced when the same amount of cooling fluid is circulated. Therefore, considering the maintenance of the conventional pressure loss, the flow rate of the cooling fluid can be increased, and a relatively large amount of heat is removed from the inlet side of the conventional cooling fluid channel. The amount of heat can be removed.

[0048] As described above, according to the present invention, the cooling efficiency by the cooling fluid in the entire fuel cell is not lowered, and at least one outlet side of the fuel gas flow path and the oxidant gas flow path is provided. In addition, the cooling effect on the inlet side can be enhanced and a suitable temperature distribution can be realized in the plane of the unit cell. In addition, in order to achieve such a suitable temperature distribution without increasing the pressure loss, the cooling fluid can be circulated without reducing the work amount (pump efficiency), and the separator is cracked due to mechanical fatigue. In addition, it is possible to provide a highly reliable polymer electrolyte fuel cell with excellent durability and heat recovery ability, which is less likely to cause cracks and electrical resistance. Furthermore, according to the present invention, it is possible to provide a separator capable of easily and reliably realizing the polymer electrolyte fuel cell as described above.

[0049] From this point of view, if flooding is prevented without reducing the water discharge performance, the fuel gas inlet side hold hole 9 and the fuel gas outlet side hold hole 10 are oxidized. Figure 3 shows the inlet gas manifold hole 11 and the oxidizing gas outlet manifold hole 12, and the cooling fluid inlet hole 13 and cooling fluid outlet hole 14. It is preferable to provide at the positions shown in -6.

That is, as shown in FIG. 3, when the main surface of the separator 5a is installed vertically, the fuel gas inlet side hold hole 9 and the oxidant gas inlet side hold are located in the upper half position. Hole 11 and cooling fluid inlet side hold hole 13 are provided, fuel gas outlet side hold hole 10 in the lower half position, oxidant gas outlet side hold hole 12 and cooling fluid outlet side It is preferable to provide the mar-hold hole 14. According to this, along the flow of the cooling fluid flow paths 8a, 8b, the upstream side of the fuel gas inlet hole 9 and the oxidant gas are provided upstream. Of the fuel gas, the fuel gas outlet side hole 10 and the oxidant gas outlet side hole 12 are present on the downstream side, and flooding is unlikely to occur.

[0051] Further, from the viewpoint of improving the durability of the battery, in the upper half position, the oxidant gas inlet side hold hole 11, the fuel gas inlet side hold hole 9 and the cooling fluid inlet port are provided. An inlet gas hold hole 11 for the oxidant gas, which is preferably provided close to the side hold hole 13, is more effective. In the lower half position, the fuel gas outlet side hole 10, the oxidant gas outlet side hole 12, and the cooling fluid outlet side hole 14 are in the lower half position. If so, they may be provided close to each other or separated from each other.

[0052] While the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

For example, in the above-described embodiment, the cooling fluid flow path is provided in both the anode side separator and the force sword side separator. In the present invention, the cooling fluid flow path is provided in at least one of the anode side separator and the force sword side separator. It only has to be.

When a plurality of unit cells are used in a stacked manner, for example, the cooling fluid channel may be provided as a cathode-side separator. A pair of channels may be formed by providing grooves on both anode side separators, or a channel for cooling fluid may be formed between both separators by providing grooves on only one separator. The constituent elements other than the structure of the separator plate can be appropriately selected within a range that does not impair the effects of the present invention.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1

[0053] Acetylene black (Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd., particle size: 35 nm), which is a conductive carbon particle, was added to a polytetrafluoroethylene (PTFE) aqueous disperse rayon (Daikin Industries, Ltd.). A water repellent ink containing 20% by mass of PTFE as a dry mass was prepared by mixing with D1). The dry mass is such that PTFE is not decomposed and the dispersion medium is sufficiently removed. Obtained experimentally under the following conditions. This water-repellent ink is applied and impregnated on carbon paper (TGPH060H manufactured by Toray Industries, Inc.), which is a conductive porous substrate that constitutes the gas diffusion layer, and is heated at 300 ° C using a hot air dryer. Heat-treated to form a gas diffusion layer (about 200 μm)

[0054] On the other hand, a catalyst obtained by supporting platinum particles on Ketjen Black (Ketjen Black EC, particle size 30 nm) manufactured by Ketjen Black International Co., Ltd., which is conductive carbon particles ( Perfluorocarbon sulfonate ionomer (a 5 mass ⁰ / oNafion dispersion manufactured by Aldrich, USA), 33 parts by mass (polymer) Dry mass). The obtained mixture was molded to form a catalyst layer (thickness 10 to 20; ζ ΐη). The dry mass was experimentally determined under conditions where the polymer electrolyte was not decomposed and the dispersion medium was sufficiently removed.

[0055] The gas diffusion layer obtained as described above and the catalyst layer are combined into an anode and a force sword, and a polymer electrolyte membrane having hydrogen ion conductivity (Nafionl 1 2 membrane manufactured by DuPont Co., Ltd. (product) Name)) was hot-pressed so that the catalyst layer faces the polymer electrolyte membrane, and an MEA having the structure shown in Fig. 1 was produced.

Next, a unit cell having the structure shown in FIG. 2 was produced using the MEA. First, the anode side separator 5a having the structure shown in FIGS. 3 and 4 and the structure shown in FIGS. 5 and 6 were used, using a graphite plate impregnated with phenol resin having an outer size of 30 cm × 32 cm × 2.5 mm. A force sword side separator 5b having was prepared.

[0056] Then, the separator 5a, 5b is provided with an oxidant gas inlet hole 11 and an oxidant gas outlet hole 12, a fuel gas inlet hole 9 and a fuel gas outlet. The side mar- hold hole 10, the cooling fluid inlet-side mar- mal hole 13, and the cooling fluid outlet-side mar- mal hole 14 were formed by cutting using an end mill. In addition, rubber plate-like gaskets 6a and 6b were disposed and joined to the outer peripheral portion of the polymer electrolyte membrane 1 in the MEA 100 at a portion corresponding to the broken line 15 in FIGS.

[0057] Next, the MEA 100 is sandwiched and fixed by the separators 5a and 5b to obtain a unit cell, and after stacking 50 unit cells to obtain a laminate, a collection of copper plates with gold plating on the surface is obtained. Stainless steel is attached to both sides of the above laminate through an electric plate and an insulating plate made of poly-sulfur sulfide. A polymer electrolyte fuel cell (fuel cell 1) of the present invention was produced by sandwiching the steel plate with steel end plates and fastening both end plates with fastening rods. The fastening pressure at this time was lOkgfZcm ² per unit area of the anode 4a and the force sword 4b.

Comparative Example 1

[0058] In this comparative example, the shape of the cooling fluid flow path in the separator 5a on the anode 4a side is constituted by two parallel grooves as shown in FIG. Each groove consists of 22 straight lines extending in the horizontal direction and 10 turn sections connecting adjacent straight lines. In addition, the shape of the cooling water flow path in the separator 5b on the side of the force sword 4b is also composed of two parallel grooves, and in the region surrounded by the broken line 15, each groove is divided into 22 horizontal directions. It consists of 10 straight turns that connect the adjacent straight parts. Other than that, a polymer electrolyte fuel cell for comparison (fuel cell 2) was produced in the same manner as in Example 1.

[0059] [Evaluation test]

Durability tests were conducted on the fuel cells 1 and 2 produced as described above.

As a fuel gas, a mixed gas of 80% hydrogen, 20% carbon dioxide, and 20ppm carbon monoxide was supplied after being moistened. At this time, it was humidified so that the dew point of the mixed gas was 70 ° C. On the other hand, as the oxidizing agent gas, air was humidified and supplied. The air was humidified so that the dew point was 70 ° C. The temperature of the cooling water, which is the cooling fluid supplied to the fuel cell, was 70 ° C, the current density was 0.3 A / cm ² , the fuel utilization rate was 70%, and the oxygen utilization rate was 40%.

[0060] Under these conditions, the change with time of the voltage of the fuel cells 1 and 2 was measured. According to this, the tendency of the battery voltage of the comparative fuel cell 2 to decrease was larger than that of the fuel cell 1 of the present invention. This is because the fuel cell 1 can remove more of the heat generated by power generation concentration at the inlet side of the fuel gas flow path and the oxidant gas flow path, and the temperature rise of the MEA can be reduced. This is thought to be because the deterioration of MEA100 on the inlet side was suppressed.

[0061] Further, since the total length of the cooling fluid channel of the fuel cell 1 of the present invention is shorter than that of the comparative fuel cell 2, the pressure loss when circulating the cooling water is approximately the length of the cooling fluid channel. 30% of the auxiliary equipment when the fuel cell 1 is installed in the system. A reduction in power was achieved.

Industrial applicability

[0062] As described above, according to the present invention, the cooling efficiency by the cooling fluid in the entire fuel cell is not reduced, and the outlet side of at least one of the fuel gas channel and the oxidant gas channel is reduced. In addition, the cooling effect on the inlet side can be enhanced to achieve a suitable temperature distribution in the plane of the unit cell, and in order to realize such a suitable temperature distribution without increasing the pressure loss, the work load Cooling fluid can be circulated without reducing (pump efficiency), cracking due to mechanical fatigue of the separator, occurrence of cracks, and increase in electrical resistance, excellent durability and heat recovery capability A polymer electrolyte fuel cell can be provided.

Accordingly, the polymer electrolyte fuel cell of the present invention is suitable as a portable fuel cell, a fuel cell for automobiles, and a fuel cell for cogeneration systems. In the polymer electrolyte fuel cell of the present invention, since the cooling effect of the cooling fluid is excellent, it is a type of fuel that needs to be controlled at a constant temperature by removing heat of reaction using the cooling fluid. It can also be suitably used for batteries such as direct methanol fuel cells.

Claims

The scope of the claims

[1] a polymer electrolyte membrane having hydrogen ion conductivity;

An anode and a force sword sandwiching the polymer electrolyte membrane;

A conductive anode-side separator including a fuel gas flow path for supplying and discharging fuel gas to and from the anode;

A force sword side separator having conductivity, including an oxidant gas flow path for supplying and discharging oxidant gas to and from the force sword;

A single cell comprising:

A cooling fluid flow path comprising at least one of two grooves of the anode side separator and the force sword side separator;

On the main surface of the anode separator and the force sword side separator on which the cooling fluid flow path is formed, an interval between adjacent grooves of the two or more grooves is the fuel gas. And at least one of the flow path for the oxidant gas and the flow path for the oxidant gas.

The number of the two or more grooves is the same from the inlet to the outlet;

The fuel cell according to claim 1, wherein the width of each of the two or more grooves is constant from the inlet to the outlet.

[2] The cooling fluid flow path constituted by the two or more grooves is a serpentine shape,

The fuel cell according to claim 1, wherein:

[3] On the main surface, an interval between adjacent grooves of the two or more grooves is from at least one of the fuel gas channel and the oxidant gas channel to the outlet.

V, it expands two-dimensionally according to!

The fuel cell according to claim 1 or 2, wherein:

[4] The two-dimensional spreading means

When assuming XY rectangular coordinates on the main surface, the gap between the grooves is wide in both the X-axis direction and the Y-axis direction.

The fuel cell according to claim 3. [5] The cooling fluid channel has a serpentine shape having a straight portion and a turn portion, and one of the X-axis direction and the Y-axis direction is substantially parallel to the straight portion. The fuel cell according to claim 4.