JP2008159319A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer electrolyte fuel cell with high reliability which is superior in durability and heat recovery capability by increasing a cooling effect at least at one of an entrance side rather than at the exit side of a fuel gas passage and an oxidizer gas passage, without decreasing as a whole the cooling efficiency by a cooling fluid. <P>SOLUTION: A cooling fluid passage which is constituted of cooling fluid passage grooves of a different number of pieces from a gas passage groove is formed on a main face on an opposite side to the main face on which at least one of a fuel gas passage or an oxidizer gas passage out of an anode side separator and a cathode side separator is formed in a fuel cell. A second cooling fluid passage groove which reaches the inside of a rib is formed at a position opposed to the rib between the gas passage groove at least at a part of the cooling fluid passage groove, and the second cooling fluid passage groove is formed at a position corresponding to the upstream region of at least the fuel gas passage or the oxidizer gas passage. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell used in a portable power source, an electric vehicle power source, a home cogeneration system, and the like.

  A conventional polymer electrolyte fuel cell using a polymer electrolyte having cation (hydrogen ion) conductivity is an electrochemical reaction between a fuel gas containing hydrogen and an oxidant gas containing oxygen such as air. By doing so, electric power and heat are generated simultaneously. FIG. 7 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. 8 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.

As shown in FIG. 7, in a membrane electrode assembly 200 of a conventional polymer electrolyte fuel cell, electrode catalysts (for example, platinum metal) are supported on both surfaces 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 the carbon powder 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 the anode 204a, and the catalyst layer 202b and the gas diffusion layer 203b are the cathode 204b. Is configured. In the catalyst layer 202a of the anode 204a, protons are generated by a reaction represented by the formula (1): H ₂ → 2H ⁺ + 2e ⁻ , and in the catalyst layer 202b of the cathode 204b, oxygen and protons transferred from the anode 204a However, water is produced by the reaction represented by the formula (2): 1 / 2O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O.

  As shown in FIG. 8, in the unit cell 210 using the MEA 200 shown in FIG. 7, the fuel gas and the oxidant gas supplied to the anode 204a and the cathode 204b are prevented from leaking to the outside. In order to prevent mixing, gaskets 206a and 206b are disposed around the anode 204a and the cathode 204b with the polymer electrolyte membrane 201 interposed therebetween. The gaskets 206a and 206b are assembled in advance with the anode 204a, the cathode 204b, and the polymer electrolyte membrane 201, and the structure obtained by integrating them may be referred to as MEA.

  The unit cell 210 has conductive separators 205a and 205b for mechanically fixing and electrically connecting adjacent unit cells. Then, in the portions where the separators 205a and 205b are in contact with the anode 204a and the cathode 204b, the reaction gas (fuel gas or oxidant gas) is supplied to the anode 204a or the cathode 204b, respectively, and the generated gas and surplus gas are carried away. Gas flow paths 207a and 207b are formed.

Furthermore, 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 cooling fluid such as cooling water is circulated to remove excess heat. 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.
The cooling water channels 208a and 208b are serpentine type cooling water channels comprising a plurality of linear grooves and turn-shaped grooves connecting the ends of the adjacent linear grooves from the upstream side to the downstream side. Are generally used, and the grooves are generally formed at equal intervals. In addition, the cooling water channels 208a and 208b may be configured by a plurality of substantially parallel linear grooves, but in this case as well, the grooves are generally formed at equal intervals.

  Here, in the plane of the unit cell 210 as described above, it is experiential that power generation and heat generation are concentrated at the inlet portion of the supplied fuel gas or oxidant gas, that is, upstream of the gas flow paths 207a and 207b. As a result, there is a problem that the temperature of the portion corresponding to the inlet portion in the MEA 200 and the separators 205a and 205b rises. In order to suppress the temperature rise at the inlet portion more effectively, it is necessary to increase the cooling water flow rate, and the work of the pump for supplying the cooling water increases. In addition, from the viewpoint of durability of the polymer electrolyte fuel cell, deterioration of the cell performance is suppressed by setting the relative humidity of the reaction gas at the electrode (anode and cathode) portion to 100% or more over the entire region, that is, a supersaturated state. It is known that

Thus, for example, in Patent Document 1, efforts are 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. Specifically, the cooling capacity of the cooling fluid is configured to be lower on the outlet side than on the inlet side of the oxidant gas flow path and / or the fuel gas flow path. There has been proposed a method intended to remove a larger amount of heat and increase the amount of saturated water vapor by increasing the temperature of the reaction gas on the outlet side to enhance the water discharge performance.
JP 2004-39540 A

  However, according to the method described in Patent Document 1, the cooling effect on the inlet side is higher than the outlet side of the fuel gas flow path and / or the oxidant gas flow path, and a predetermined temperature distribution is formed in the plane of the unit cell. Although it is possible to do so, there is a possibility that the cooling efficiency of the cooling fluid on the outlet side will be reduced, but the cooling efficiency will be reduced as a whole.

  Further, in the invention 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 where the cooling capacity is reduced in the cooling water flow path of the separator. The width of the groove {that is, the pitch between the flow paths} is extremely wide. Therefore, the cross-sectional area of the cooling water flow path on the downstream side becomes large, the speed at which the cooling water flows per unit area on the downstream side or the outlet side is reduced, and heat exchange may be insufficient. Therefore, it is necessary to flow excess cooling water in order to achieve a predetermined amount of heat removal in the surface of the unit cell, and the work of the pump for supplying the cooling water increases, and cooling water flow paths are provided at equal intervals. As in the case of the case, when the fuel cell is systemized, the overall efficiency of the entire system is reduced.

  Furthermore, as described above, the separator described in Patent Document 1 has a mechanical strength because the number of grooves is reduced by reducing the number of ribs separating the grooves in the downstream region. When a single cell using the separator is laminated and a stack for a fuel cell is produced and fastened, there is a problem that there is a concern about cracking or cracking due to mechanical fatigue of the separator, and There is also a problem that the contact area with the anode or the cathode is small, and the efficiency is lowered due to an increase in electrical resistance.

  Accordingly, the present invention has been made in view of the above problems, and at least one outlet of the fuel gas channel and the oxidant gas channel without lowering the cooling efficiency by the cooling fluid in the entire fuel cell. In order to increase the cooling effect on the inlet side rather than the side to realize a preferable temperature distribution in the plane of the unit cell, and further, it becomes unnecessary to supply cooling water unnecessarily by increasing the cooling efficiency. Cooling fluid can be circulated without increasing the power consumption of the pump, and it is difficult to increase mechanical fatigue and electrical resistance of the separator. It is a highly reliable polymer electrolyte with excellent durability and heat recovery capability. An object is to provide a fuel cell. Furthermore, another object of the present invention is to provide a separator capable of easily and reliably realizing the polymer electrolyte fuel cell as described above.

  The present inventors diligently studied to achieve the above object, and as a result, the fuel gas flow channel or the oxidant gas flow in the cooling fluid flow channel constituted by a number of grooves different from the gas flow channel. The second groove reaching the inside of the rib is provided in a portion facing the rib portion of the passage, and the groove is formed at least in a portion located on the upstream side of the gas flow path. The present inventors have found that the above problems can be solved and have completed the present invention.

That is, in order to solve the above problems, the present inventor
A polymer electrolyte membrane having hydrogen ion conductivity;
An anode and a cathode sandwiching a polymer electrolyte membrane;
A conductive anode-side separator including a fuel gas flow path comprising a plurality of gas flow path grooves for supplying and discharging fuel gas to and from the main surface facing the anode;
A conductive cathode-side separator having an oxidant gas flow path formed of a plurality of gas flow path grooves for supplying and discharging an oxidant gas to and from the cathode on a main surface facing the cathode;
A single cell comprising:
At least one of the anode-side separator and the cathode-side separator has a different number of cooling fluids from the gas flow channel grooves on the main surface opposite to the main surface on which the fuel gas flow channel or the oxidant gas flow channel is formed. Having a cooling fluid flow path composed of flow path grooves,
At least a part of the cooling fluid channel groove has a second cooling fluid channel groove reaching the inside of the rib at a position facing the rib between the gas channel grooves, and The second cooling fluid channel groove is formed at a position corresponding to the upstream region of at least one of the fuel gas channel and the oxidant gas channel;
A fuel cell is provided.

  Here, the “upstream region” of at least one of the fuel gas flow channel and the oxidant gas flow channel is the fuel from the normal direction of the main surface of the anode separator in the case of the “upstream region” of the fuel gas flow channel. When projecting the gas flow channel groove that constitutes the gas flow channel (when projected at the same magnification), a figure indicating the “gas flow channel groove constituting the upstream portion of the fuel gas flow channel” ( As a result of the projection, it refers to a region having the same size and shape as a “figure that can be seen as a gas channel groove constituting the upstream portion of the fuel gas channel”. In addition, in the case of the “upstream region” of the oxidant gas flow path, when the gas flow channel groove constituting the oxidant gas flow path is projected from the normal direction of the main surface of the cathode separator (projected at the same magnification) The figure showing the “groove for the gas flow path constituting the upstream portion of the oxidant gas flow path” (projected result is “for the gas flow path constituting the upstream portion of the oxidant gas flow path”). It is a region having the same size and shape as a figure showing a “groove”.

The “upstream part of at least one of the fuel gas channel and the oxidant gas channel” refers to the first half of the total channel length of the fuel gas channel in the case of the “upstream region” of the fuel gas channel. (1/2 part). More specifically, the “upstream portion of the fuel gas flow path” refers to the length from the upstream side to the downstream side of the total length of the fuel gas flow path located in the portion corresponding to the anode (electrode part). The first half part (1/2 part). And, the “part corresponding to the anode (electrode part)” is the case where the “anode (particularly the catalyst layer)” is projected from the normal direction of the main surface of the anode separator (projected at the same magnification) The portion having the same size and shape as the above-mentioned figure showing the “anode (especially the catalyst layer)” (the figure which appears as a result of showing the “anode (particularly the catalyst layer)”), A portion that overlaps in a state corresponding to a figure showing “anode (particularly catalyst layer)”.
Further, in the case of the “upstream region” of the oxidant gas flow path, it refers to the first half (1/2) of the total flow path length of the oxidant gas flow path. More specifically, the “upstream part of the oxidant gas flow path” refers to the downstream from the upstream side of the total flow path length of the oxidant gas flow path located in the part (electrode part) corresponding to the cathode. The first half part (1/2 part) over the side. And, the “part corresponding to the cathode (electrode part)” is the case where the “cathode (especially the catalyst layer)” is projected from the normal direction of the main surface of the cathode separator (projected at the same magnification). The portion having the same size and shape as the above-described figure showing the “cathode (especially the catalyst layer)” (the figure which is projected and seen as showing the “cathode (especially the catalyst layer)), It refers to the overlapping part in a state consistent with the figure showing “cathode (especially catalyst layer)”.

  In addition, the “position facing the rib between the gas flow channel grooves” in the cooling fluid flow channel groove means “the fuel gas flow channel from the normal direction of the main surface of the anode side separator or the cathode side separator”. Alternatively, when the “oxidant gas flow path (or gas flow path groove)” is projected (when projected at the same magnification), the above-mentioned “gas flow A position indicating the same size and shape as a figure indicating “ribs between the groove for road” (a figure that appears as a “rib between the groove for gas flow path” as a result of projection) It refers to the position where it overlaps with the figure indicating the “rib between the gas flow channel grooves”.

  By adopting the configuration as described above, the cooling effect on the inlet side rather than the outlet side of 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. And a suitable temperature distribution can be realized in the plane of the unit cell. Further, since the cooling fluid flows under the rib portion forming the gas flow path, it is possible to more effectively remove the heat generated in the MEA by power generation. Furthermore, in order to achieve such a suitable temperature distribution without increasing the pressure loss of the cooling fluid, the cooling fluid can be circulated without reducing the work (pump efficiency), and the mechanical fatigue of the separator In addition, it is possible to provide a highly reliable polymer electrolyte fuel cell excellent in durability and heat recovery capability, in which increase in electrical resistance and electrical resistance are unlikely to occur.

  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, from the outlets of the fuel gas channel and the oxidant gas channel. Although it is possible to increase the cooling effect at the inlet and form a temperature distribution in the plane of the unit cell, the cooling efficiency of the whole fuel cell is reduced, the pressure loss is increased, the work (pump efficiency) is reduced, and It has been difficult to prevent a decrease in separator strength and an increase in electrical resistance. Assuming the case where the polymer electrolyte fuel cell is used in an on-site type cogeneration system, heat recovery is a very important factor. From this point of view, the polymer electrolyte described in Patent Document 1 is used. There was a problem with the fuel cell. In addition, when applied to automobile applications, since the amount of power generation per unit area is further increased, a fuel cell with higher cooling efficiency is required. From this viewpoint as well, the polymer described in Patent Document 1 is required. An electrolyte fuel cell was insufficient.

  The present invention eliminates such a conventional problem, and reduces the cooling efficiency of the entire fuel cell by the cooling fluid, without reducing the cooling efficiency of at least one of the fuel gas channel and the oxidant gas channel. In order to realize a suitable temperature distribution in the surface of the unit cell by increasing the cooling effect in the cell, and to realize such a suitable temperature distribution without increasing the pressure loss, the work load (pump efficiency) Providing a highly reliable polymer electrolyte fuel cell with excellent durability and heat recovery capability, which can circulate cooling fluid without reducing the flow rate, is unlikely to increase mechanical fatigue and electrical resistance of the separator It is intended to do.

  Furthermore, the present invention improves the cooling effect on the inlet side of at least one of the fuel gas channel and the oxidant gas channel without lowering the cooling efficiency by the cooling fluid in the entire fuel cell. A suitable temperature distribution can be realized in the plane of the unit cell, and in order to realize such a suitable temperature distribution without increasing the pressure loss, the cooling fluid can be supplied without reducing the work (pump efficiency). To provide a separator that can easily and surely realize a polymer electrolyte fuel cell that can be distributed and that has excellent durability and heat recovery capability, and that is less likely to cause mechanical fatigue and increase in electrical resistance. It is the purpose.

  According to the present invention, 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 flow channel and the oxidant gas flow channel is reduced. In order to increase the cooling effect on the inlet side and realize a suitable temperature distribution in the plane of the unit cell, and to realize such a suitable temperature distribution without increasing the pressure loss, the work load (pump To provide a polymer electrolyte fuel cell that can circulate a cooling fluid without reducing (efficiency) and is excellent in durability and heat recovery ability, in which mechanical fatigue and electrical resistance of a separator are unlikely to increase. Can do. Furthermore, according to the present invention, it is possible to provide a separator that can easily and surely realize the polymer electrolyte fuel cell as described above, and is less prone to mechanical fatigue and electrical resistance.

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 description 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 a basic configuration of a unit cell using the membrane electrode assembly shown in FIG.

  As shown in FIG. 1, in the polymer electrolyte fuel cell MEA 100 of the present invention, a polymer electrolyte membrane (for example, Nafion (trade name) manufactured by DuPont, USA) 1 that selectively transports hydrogen ions is used. On both sides, catalyst layers 2a and 2b made of a mixture of conductive carbon particles carrying an electrode catalyst (for example, a noble metal such as platinum) and a polymer electrolyte having hydrogen ion conductivity are formed. The catalyst layers 2a and 2b are formed by a method known in the art using an ink for forming a catalyst layer containing conductive carbon particles carrying a noble metal electrode catalyst, a polymer electrolyte, and a dispersion medium. can do.

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 the anode 4a, and the catalyst layer 2b and the gas diffusion layer 3b are the cathode 4b. Is configured. 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, a conductive porous substrate such as carbon cloth or carbon paper can be used. The conductive porous base material may have a configuration in which water repellent treatment is performed by a conventionally known method.
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 a technique known in the art.

  Next, as shown in FIG. 2, the unit cell 110 using the MEA 100 shown in FIG. 1 includes the fuel gas and the oxidant gas supplied to the anode 4a and the cathode 4b to prevent leakage to the outside. Gaskets 6a and 6b are disposed around the anode 4a and the cathode 4b with the polymer electrolyte membrane 1 interposed therebetween to prevent the gas from mixing. Conventionally known gaskets can also be used as the gaskets 6a and 6b.

  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 cathode 4b to the portion where the separators 5a and 5b are in contact with the anode 4a and the cathode 4b, respectively, and the generated gas and surplus gas are carried away. Gas flow paths 7a and 7b are formed. Such separators 5a and 5b mechanically fix and electrically connect adjacent unit cells when two or more unit cells 110 are stacked.

  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 cooling fluid such as cooling water is circulated to remove excess heat. That is, heat recovery is performed. Therefore, in both separators 5a and 5b in the present embodiment, cooling water passages 8a and 8b are provided on the surface opposite to the surface on which the gas passages 7a and 7b are formed. The cooling fluid is circulated.

In FIG. 2, cooling fluid flow paths 8 a and 8 b 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, every two to three unit cells are used. A cooling fluid channel may be disposed. When the cooling fluid flow path is not formed between the single cells, a fuel gas flow path is provided on one surface, and an oxidant gas flow path is provided on the other surface. It is also possible to use a single separator that also serves as the above.
Moreover, as a material of a separator board, there exist metal, carbon, the material excellent in the heat conductivity and electroconductivity which mixed graphite and resin, These can be used widely. 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.

  Here, as described above, in the conventional polymer electrolyte fuel cell, the cooling effect at the inlet rather than the outlet of the fuel gas channel and the oxidant gas channel is caused by the shape of the cooling fluid channel in the separator. Although it is possible to form a temperature distribution in the plane of the unit cell by increasing the temperature, the cooling efficiency of the entire fuel cell is reduced, the work (pump efficiency) is reduced, and the mechanical fatigue and electrical resistance of the separator are reduced. There was a problem of increase. In the present invention, in order to solve such a problem, a cooling fluid flow path having a shape different from the conventional one is used, and a separator having a completely new configuration is used.

Hereinafter, the separator (embodiment of the separator of the present invention) used in the unit cell 110 mounted on the polymer electrolyte fuel cell of the present invention will be described in more detail with reference to the drawings.
In the separators 5a and 5b shown in FIG. 2, the cooling fluid flow at positions facing the ribs in contact with the anode 4a and the cathode 4b (that is, the ribs between the gas flow channel grooves constituting the anode 4a and the cathode 4b). Second cooling fluid grooves 9a and 9b are formed in the paths 8a and 8b (that is, the cooling fluid flow path grooves). This makes it possible to effectively remove the heat generated by the MEA due to power generation.

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 fuel gas flow path 7a side. It is the front view seen 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 cooling fluid flow path 8a side.
As shown in FIGS. 3 and 4, the separator 5a on the anode 4a side includes an oxidant gas inlet manifold hole 12, an oxidant gas outlet manifold hole 13, a fuel gas inlet manifold hole 10 and a fuel gas inlet. It has an outlet side manifold hole 11, a cooling fluid inlet side manifold hole 14, and a cooling fluid outlet side manifold hole 15.
The separator 5a has a fuel gas flow path 7a connecting the fuel gas manifold holes 10 and 11 on the surface facing the anode 4a, and a cooling fluid flow connecting the cooling fluid manifold holes 14 and 15 on the back surface. It has a path 8a.

  3 and 4, the regions surrounded by the broken line 16 indicate the portions (electrode portions) corresponding to the anode 4 a of the MEA 100. And as shown in FIG. 4, the cooling fluid flow path 8a is comprised by the serpentine-like groove | channel, and each groove | channel is 4 pieces which connect the 5 linear parts (long groove) extended in the horizontal direction, and the adjacent linear part. The turn part (short 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. In addition, although the cooling fluid flow path 8a in FIG. 4 is configured by one cooling fluid flow path groove, a plurality of parallel cooling fluid flow path grooves may be configured in parallel. A part of the cooling fluid channel groove constituting the cooling fluid channel 8a includes a second cooling fluid channel groove 9a reaching the inside of the rib at a position facing the rib in the upstream region of the fuel gas channel 7a. Is formed (see FIG. 2).

  Further, as shown in FIG. 3, the fuel gas flow path 7a is composed of nine straight portions (long grooves) extending in the horizontal direction and eight turn portions (short grooves) connecting adjacent straight portions. Yes. 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. Further, although the fuel gas flow path 7a is constituted by one gas flow path groove, a plurality of gas flow path grooves may be arranged in parallel.

On the other hand, FIG. 5 is a front view of the separator 5b on the cathode 4b side in the unit cell 110 shown in FIG. 2 as viewed from the oxidant gas flow path 7b side. FIG. 6 is a rear view of the separator 5b on the cathode 4b side in the unit cell 110 shown in FIG. 5, that is, a front view seen from the cooling fluid channel 8b side.
As shown in FIGS. 5 and 6, the separator 5b on the cathode 4b side includes an oxidant gas inlet manifold hole 12, an oxidant gas outlet manifold hole 13, a fuel gas inlet manifold hole 10 and a fuel gas inlet. It has an outlet side manifold hole 11, a cooling fluid inlet side manifold hole 14, and a cooling fluid outlet side manifold hole 15.
The separator 5b has an oxidant gas flow path 7b that connects the oxidant gas manifold holes 12 and 13 on the surface facing the cathode 4b, and a cooling that connects the cooling fluid manifold holes 14 and 15 on the back surface. A fluid flow path 8b is provided.

In FIG. 5 and FIG. 6, regions surrounded by a broken line 16 indicate portions (electrode portions) corresponding to the cathode 4b of the MEA 100, respectively.
And as shown in FIG. 6, the cooling fluid flow path 8b is comprised by the serpentine-like groove | channel, and each groove | channel is 4 pieces which connect the 5 linear parts (long groove) extended in the horizontal direction, and the adjacent linear part. The turn part (short 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. Further, although the cooling fluid flow path 8b in FIG. 6 is configured by one cooling fluid flow path groove, a plurality of cooling fluid flow path grooves may be configured in parallel. In addition, a second cooling fluid channel that reaches the inside of the rib at a position facing the rib in the upstream region of the oxidant gas channel 7b is provided in a part of the groove for the cooling fluid channel that constitutes the cooling fluid channel 8b. Grooves 9b are formed (see FIG. 2).

  As shown in FIG. 5, the oxidant gas flow path 7b is composed of nine straight portions (long grooves) extending in the horizontal direction and eight turn portions (short grooves) connecting adjacent straight portions. Yes. 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. The oxidant gas flow path 7b is configured by a single gas flow path groove, but may be configured to have a plurality of gas flow path grooves in parallel.

  As described above, in the separators 5a and 5b of the present embodiment, a part of the cooling fluid channel grooves constituting the cooling fluid channels 8a and 8b are formed by the anode gas channel 7a and the cathode gas flow. A second cooling fluid flow path groove 9a, 9b reaching the inside of the rib 7a1, 7b1 at a position facing the ribs 7a1, 7b1 between the gas flow path grooves constituting the path 7b; Second cooling fluid channel grooves 9a and 9b are formed at positions corresponding to upstream regions of the fuel gas channel 8a and the oxidant gas channel 8b, respectively.

  By having such a configuration, the inlets (fuel gas inlet side manifold hole 10 and oxidant gas inlet side manifold hole) of the flow path of the reaction gas (fuel gas and oxidant gas) in the separators 5a and 5b in the present invention. 12) On the upstream 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 (fuel gas outlet side manifold hole 11 and oxidant gas outlet side manifold hole 13) side of the flow path of the reaction gas (fuel gas and oxidant gas) in the separators 5a and 5b, that is, on the downstream side, The amount of cooling fluid contributing to heat exchange is reduced per unit volume of the separators 5a and 5b. Therefore, a higher cooling effect can be exhibited on the upstream side with a larger amount of heat generation. In addition, since the groove shapes of the cooling fluid channels 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 reduced.

  Further, in the separators 5a and 5b, second cooling fluid grooves 9a and 9b are formed in the cooling fluid flow paths 8a and 8b facing the ribs 7a1 and 7b1 in contact with the anode 4a and the cathode 4b, respectively. It is possible to more effectively remove the heat generated by the MEA. Furthermore, since the number of grooves constituting the cooling fluid flow paths 8a and 8b is not changed, there is no problem of a decrease in cooling fluid distribution when the number of grooves is increased.

  As described above, according to the present invention, the cooling on the inlet side of at least one outlet side of the fuel gas channel and the oxidant gas channel is reduced without reducing the cooling efficiency by the cooling fluid in the entire fuel cell. It is possible to enhance the effect and realize a suitable temperature distribution in the plane of the unit cell. Moreover, in order to realize 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 mechanical fatigue and electrical properties of the separator It is possible to provide a highly reliable polymer electrolyte fuel cell excellent in durability and heat recovery ability, in which resistance is hardly increased. 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.

  Here, from the viewpoint of preventing flooding without reducing water discharge performance, the fuel gas inlet side manifold hole 10, the fuel gas outlet side manifold hole 11, the oxidant gas inlet side manifold hole 12, and the oxidant are used. The gas outlet side manifold hole 13, the cooling body inlet side manifold hole 14 and the cooling fluid outlet side manifold hole 15 are preferably provided at the positions shown in FIGS.

  That is, as shown in FIG. 4, when the main surface of the separator 5a is installed vertically, the fuel gas inlet side manifold hole 10, the oxidant gas inlet side manifold hole 12 and the cooling fluid inlet are located in the upper half position. Preferably, a side manifold hole 14 is provided, and an outlet side manifold hole 11 for the fuel gas, an outlet side manifold hole 13 for the oxidant gas, and an outlet side manifold hole 15 for the cooling fluid are provided in the lower half position. According to this, the fuel gas inlet manifold hole 10 and the oxidant gas inlet manifold hole 12 exist on the upstream side along the flow of the cooling fluid flow paths 8a and 8b, and the fuel gas outlet side on the downstream side. The manifold hole 11 and the oxidant gas outlet side manifold hole 13 are present, and flooding is unlikely to occur.

  From the viewpoint of improving the durability of the battery, in the upper half position, the inlet side manifold hole 12 for the oxidant gas, the inlet side manifold hole 10 for the fuel gas, and the inlet side manifold hole 14 for the cooling fluid are close to each other. It is preferable to provide it, and it is more effective to provide the inlet manifold hole 12 for the oxidant gas nearby. In the lower half position, the fuel gas outlet side manifold hole 11, the oxidant gas outlet side manifold hole 13 and the cooling fluid outlet side manifold hole 15 are provided close to each other in the lower half position. However, it may be provided separately.

The preferred embodiment of the present invention has been described above, but 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 cathode-side separator. However, in the present invention, it may be provided in at least one of the anode-side separator and the cathode-side separator. .
When a plurality of unit cells are stacked and used, for example, the cooling fluid channel may be provided at a rate of one to two or three cells, and the cooling fluid channel is provided with a cathode side separator and an anode side separator. Alternatively, grooves may be provided on both sides to form a set of flow paths, or grooves may be provided only on one separator, thereby forming a cooling fluid flow path between both separators.

In addition, as in the above-described embodiment, the second cooling reaches the inside of the rib at a position where at least a part of the cooling fluid channel groove faces the rib between the gas channel grooves. It is sufficient if the groove for fluid flow path is provided and the second groove for cooling fluid flow path is formed at a position corresponding to the upstream region of the fuel gas flow path or the oxidant gas flow path. The cooling fluid channel groove has a second cooling fluid channel groove reaching the inside of the rib at a position facing the rib between the gas channel grooves, over the entire portion corresponding to And the 2nd groove | channel for cooling fluid flow paths may be formed in the position corresponding to the whole area | region of a fuel gas flow path or an oxidant gas flow path.
In addition, there is no restriction | limiting in particular about components other than the structure of a separator board, It can select suitably in the range which does not impair the effect of this invention.

  As described above, according to the present invention, the cooling on the inlet side of at least one outlet side of the fuel gas channel and the oxidant gas channel is reduced without reducing the cooling efficiency by the cooling fluid in the entire fuel cell. It is possible to increase the effect and realize a preferable temperature distribution in the plane of the unit cell, and to reduce the work (pump efficiency) in order to realize such a preferable temperature distribution without increasing the pressure loss. It is possible to provide a polymer electrolyte fuel cell that can circulate a cooling fluid without causing any mechanical fatigue or increase in electrical resistance of the separator and has excellent durability and heat recovery capability.

  Therefore, the polymer electrolyte fuel cell of the present invention is suitable as a fuel cell for portable fuel cells, automobile fuel cells, and cogeneration systems. Further, in the polymer electrolyte fuel cell of the present invention, since the cooling effect of the cooling fluid is excellent, the type of fuel cell that needs to control the temperature constant by removing reaction heat using the cooling fluid, etc. For example, it can be suitably used for a direct methanol fuel cell.

It is a schematic sectional drawing which shows an example of the basic composition of the membrane electrode assembly (MEA) contained in the single cell mounted in the polymer electrolyte fuel cell of this invention. It is a schematic sectional drawing which shows an example of the basic composition of the cell using the membrane electrode assembly shown in FIG. 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 fuel gas flow path 7a 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 seen from the cooling fluid flow path 8a side. FIG. 3 is a front view of the single battery 110 shown in FIG. 2 as viewed from the oxidant gas flow path 7b side of the separator 5b on the cathode 4b side. FIG. 6 is a rear view of the separator 5b on the cathode 4b side in the unit cell 110 shown in FIG. 5, that is, a front view seen from the cooling fluid flow path 8b side. It is a schematic sectional drawing which shows an example of the basic composition of the membrane electrode assembly (MEA) contained in the single cell mounted in the conventional polymer electrolyte fuel cell. It is a schematic sectional drawing which shows an example of the basic composition of the cell using the membrane electrode assembly shown in FIG.

Explanation of symbols

  1, 201 ... polymer electrolyte membrane, 2a, 2b, 202a, 202b ... catalyst layer, 3a, 3b, 203a, 203b ... gas diffusion layer, 4a, 204a ... anode, 4b, 204b ..Cathode, 5a, 205a ... anode side separator, 5b, 205b ... cathode side separator, 6a, 6b, 206a, 206b ... gasket, 7a, 207a ... fuel gas flow path, 7b, 207b ... Oxidant gas channel, 7a1, 7b ... Rib, 18a, 8b, 208a, 208b ... Cooling fluid channel, 9a, 9b ... Second cooling fluid channel groove, 10. ..Fuel gas inlet side manifold hole, 11 ... Fuel gas outlet side manifold hole, 12 ... Oxidant gas inlet side manifold hole, 13 ... Oxidant gas outlet side manifold De hole, inlet side manifold holes, 14 ... cooling fluid, 15 ... cooling fluid outlet side manifold aperture, 100, 200 ... MEA, 110, 210 ... unit cell

Claims (1)

A polymer electrolyte membrane having hydrogen ion conductivity;
An anode and a cathode sandwiching the polymer electrolyte membrane;
A conductive anode-side separator including a fuel gas flow path including a plurality of gas flow path grooves for supplying and discharging fuel gas to and from the main surface facing the anode;
A conductive cathode-side separator having an oxidant gas flow path formed of a plurality of gas flow path grooves for supplying and discharging an oxidant gas to and from the cathode on a main surface facing the cathode;
A single cell comprising:
At least one of the anode-side separator and the cathode-side separator has a gas channel groove on a main surface opposite to the main surface on which the fuel gas channel or the oxidant gas channel is formed. And a cooling fluid flow path composed of a different number of cooling fluid flow path grooves,
At least a part of the cooling fluid channel groove has a second cooling fluid channel groove reaching the inside of the rib at a position facing the rib between the gas channel grooves. And the second cooling fluid channel groove is formed at a position corresponding to an upstream region of at least one of the fuel gas channel and the oxidant gas channel,
A fuel cell.

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