JP2009080943A - Fuel cell separator and fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel battery separator which improves the drain properties of a gas channel to inhibit waterdrops from blocking the gas channel, and a fuel battery having the fuel battery separator. <P>SOLUTION: The fuel battery separator includes a gas entrance side manifold and a gas exit side manifold, the gas channel communicating with the gas entrance side manifold and the gas exit side manifold, and ribs dividing the gas channel into a plurality of sub gas channels. The ends of the ribs that face the gas exit side manifold are formed to be thinner than the bodies of the ribs. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell separator and a fuel cell technology.

  Generally, a fuel cell has a membrane-electrode assembly including a pair of electrodes (anode electrode and cathode electrode) sandwiching both sides of an electrolyte membrane, and a pair of fuel cell separators sandwiching both sides of the membrane-electrode assembly. . The anode electrode has an anode electrode catalyst layer and a diffusion layer, and the cathode electrode has a cathode electrode catalyst layer and a diffusion layer. At the time of power generation of the fuel cell, when the anode gas supplied to the anode electrode is hydrogen gas, and the cathode gas supplied to the cathode electrode is oxygen gas, a reaction to form hydrogen ions and electrons is performed on the anode electrode side. The electrons reach the cathode electrode through an external circuit through the electrolyte membrane to the cathode electrode side. On the other hand, on the cathode side, hydrogen ions, electrons, and oxygen gas react to generate moisture, and energy is released.

  FIG. 9 is a schematic plan view showing a configuration of a conventional fuel cell separator. As shown in FIG. 9, the fuel cell separator 50 is formed with a gas flow path 52, an anode gas inlet side manifold 54a, an anode gas outlet side manifold 54b, a cathode gas inlet side manifold 54c, and a cathode gas outlet side manifold 54d. ing. The gas flow path 52 formed on one surface of the fuel cell separator 50 communicates with the anode gas inlet side manifold 54a and the anode gas outlet side manifold 54b, and the gas flow path (not shown) formed on the other surface is The cathode gas inlet side manifold 54c and the cathode gas outlet side manifold 54d communicate with each other. The gas flow path 52 is divided into a plurality of parts by ribs 56.

  Since each manifold (54a, 54b, 54c, 54d) and the gas flow path 52 are passages for the reaction gas (anode gas, cathode gas) humidified for maintaining the ion conductivity of the electrolyte membrane, the humidity is high. Water droplets are likely to occur due to condensation. In general, since the gas channel 52 has a narrow channel width, if the gas channel 52 has poor drainage, water droplets may accumulate, and so-called flooding may occur that blocks the gas channel 52. In particular, the gas flow path 52 in the vicinity of the gas outlet side manifolds (54b, 54d) from which the reaction gas is discharged is likely to be blocked by water droplets. In such a state, the supply of the reaction gas is hindered, the voltage of the fuel cell is lowered, and the battery performance may be lowered.

  For example, in Patent Document 1, an electrode portion that contacts a rib of a fuel cell separator is formed by forming a rib that contacts the electrode and a shallow groove having a depth smaller than the height of the rib on the electrode contact surface of the rib. A fuel cell separator that can reduce flooding is proposed.

  Further, for securing the structural strength of the coolant passage of the fuel cell separator, for example, Patent Document 2 discloses a first rib formed at an intermediate portion of the coolant passage and a first rib. Separately, a fuel cell separator has been proposed that includes a second rib formed in an island shape at the end of the coolant passage.

JP 2007-115525 A JP 2001-110434 A

  However, in the fuel cell separators of Patent Documents 1 and 2, it is difficult to improve the drainage of the gas channel having a narrow channel width, and the gas channel may be blocked by water droplets.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel cell separator that can improve the drainage of a gas channel and suppress the gas channel from being blocked by water droplets, and a fuel cell including the fuel cell separator. There is to do.

  The present invention relates to a fuel in which a gas inlet manifold and a gas outlet manifold, a gas passage communicating with the gas inlet manifold and the gas outlet manifold, and a rib for dividing the gas passage into a plurality of parts are formed. In the battery separator, an end portion of a rib facing the gas outlet side manifold is formed to be narrower than a main body portion of the rib.

  In the fuel cell separator, it is preferable that at least an end portion of the rib is formed so as to be narrower toward the gas outlet side manifold.

  In the fuel cell separator, the rib is preferably formed intermittently.

  In the fuel cell separator, it is preferable that an end portion of the rib protrudes into the gas outlet side manifold.

  In the present invention, a gas inlet side manifold and a gas outlet side manifold, a gas flow path communicating with the gas inlet side manifold and the gas outlet side manifold, and a rib for dividing the gas flow path into a plurality of parts are formed. In the fuel cell separator, the end portion of the rib facing the gas outlet side manifold is formed so as to widen the width of the gas flow path.

  The present invention also provides a fuel cell having a pair of fuel cell separators that sandwich a membrane-electrode assembly, wherein at least one of the fuel cell separators includes a gas inlet side manifold, a gas outlet side manifold, and the gas A gas flow path communicating with the inlet side manifold and the gas outlet side manifold and a rib dividing the gas flow path into a plurality of parts are formed, and an end of the rib facing the gas inlet side manifold is a main body of the rib. It is formed narrower than the part.

  According to the present invention, a separator for a fuel cell in which an inlet side manifold and an outlet side manifold, a gas flow path communicating with the gas inlet side manifold and the gas outlet side manifold, and a rib dividing the gas flow path into a plurality of parts are formed. The end of the rib facing the gas outlet side manifold is formed narrower than the main body of the rib, thereby improving the drainage of the gas flow path and closing the gas flow path with water droplets. It is possible to provide a fuel cell separator and a fuel cell including the fuel cell separator.

  Embodiments of the present invention will be described below.

  FIG. 1 is a partial schematic cross-sectional view showing an example of the configuration of a fuel cell according to an embodiment of the present invention. As shown in FIG. 1, the fuel cell 1 includes a membrane-electrode assembly 10, an anode separator 12 as a fuel cell separator, a cathode separator 14, and a sealing plate 16. As shown in FIG. 1, an anode electrode separator 12 and a cathode electrode separator 14 are disposed in a fuel cell 1 via a membrane-electrode assembly 10. The membrane-electrode assembly 10 includes an anode electrode (not shown) and a cathode electrode (not shown) arranged via an electrolyte membrane (not shown). The anode electrode separator 12 and the cathode electrode separator 14 are bonded by an adhesive 13.

  The anode separator 12 and the cathode separator 14 used in the present embodiment are not particularly limited, such as a metal separator or a carbon separator.

  2A is a schematic plan view showing an example of the configuration of the anode separator according to the embodiment of the present invention, and FIG. 2B is an example of the configuration of the cathode separator according to the embodiment of the present invention. It is a schematic plan view which shows.

  2A and 2B, the fuel cell separator (anode electrode separator 12 and cathode electrode separator 14) includes an anode gas inlet side manifold 18, an anode gas outlet side manifold 20, and a cathode gas inlet side. A manifold 22 and a cathode gas outlet side manifold 24 are formed. The arrangement of each manifold is not particularly limited.

  Further, as shown in FIG. 2A, the anode separator 12 is formed in the anode electrode separator 12 so as to communicate with the anode gas inlet side manifold 18 and the anode gas outlet side manifold 20. Has been. As shown in FIG. 2B, the cathode electrode separator 14 is formed with a cathode gas passage 28 as a gas passage so as to communicate with the cathode gas inlet side manifold 22 and the cathode gas outlet side manifold 24. Yes. The anode gas channel 26 and the cathode gas channel 28 are each divided into a plurality of ribs 30.

  FIG. 3 is a partially enlarged schematic plan view of the anode electrode separator in the dotted frame R in FIG. As shown in FIG. 3, the rib end portion 31a facing the anode gas outlet side manifold 20 is formed narrower than the rib main body portion 31b. Thereby, the flow path width of the anode gas flow path 26 facing the anode gas outlet side manifold 20 can be increased. Since the water droplets are drained along the flow of the reaction gas, they remain in the vicinity of the gas outlet side manifold (for example, the anode gas outlet side manifold 20 and the cathode gas outlet side manifold 24 shown in FIG. 2) from which the reaction gas is discharged. easy. Therefore, the rib end portion 31a is narrower than the rib main body portion 31b, and the flow path width of the anode gas flow path 26 is widened, so that blockage of the anode gas flow path 26 due to water droplets can be suppressed. Further, since the rib end portion 31a is formed to be narrow, it is difficult for water droplets to be held at the tip of the rib end portion 31a, and the anode gas outlet side manifold 20 can easily drain water droplets.

  Further, the shape of the narrow rib end 31a is not limited to a rectangular shape as shown in FIG. 4A to 4C are partially enlarged schematic plan views of the anode electrode separator in the dotted frame R of FIG. For example, the rib end portion 31a can easily drain water droplets adhering to the tip of the rib end portion 31a to the manifold. As described above, it is preferable that the width of the anode gas outlet side manifold 20 increases toward the anode gas outlet side manifold 20. In the present embodiment, as shown in FIGS. 4A to 4C, the rib end portion 31a may be formed narrower toward the anode gas outlet side manifold 20, or the entire rib 30 may be the anode. It may be formed narrower toward the gas outlet side manifold.

  In the present embodiment, the rib end portion 31a facing the anode gas outlet side manifold 20 is not limited to the exemplified rib end portion 31a, and the rib end portion facing the cathode gas outlet side manifold 24 is similarly described above. It is preferable that the end part 31a is formed. That is, the above-described rib end portion 31a may be formed on at least one of the rib end portion facing the anode gas outlet side manifold and the rib end portion facing the cathode gas outlet side manifold.

  Next, the flow of reaction gas flowing through the fuel cell separator and the time of power generation will be described.

  On the anode electrode separator 12 side, the humidified anode gas is supplied from the anode gas inlet side manifold 18 shown in FIG. The anode gas flowing through the anode gas passage 26 is supplied to the membrane-electrode assembly 10 shown in FIG. 1 and used for power generation. Then, the anode gas passes through the anode gas outlet side manifold 20 from the anode gas flow path 26 shown in FIG. 2 and is discharged to the outside of the anode electrode separator 12. On the other hand, on the cathode separator 14 side, the humidified cathode gas is supplied from the cathode gas inlet side manifold 22 shown in FIG. The cathode gas flowing through the cathode gas flow path 28 is supplied to the membrane-electrode assembly 10 shown in FIG. 1 and used for power generation. Then, the cathode gas passes through the cathode gas outlet side manifold 24 from the cathode gas flow path 28 shown in FIG. 2 and is discharged to the outside of the cathode electrode separator 14.

  As described above, each manifold and each reaction gas flow path are passages for humidified reaction gas (anode gas, cathode gas), and the humidity increases as the reaction gas flows, so that water droplets are easily generated due to condensation or the like. Become. Further, the water is generated by power generation on the cathode electrode side, and the humidity is also increased on the anode electrode side due to the water generated on the cathode electrode moving through the electrolyte membrane.

  FIG. 5 (a) is a partially enlarged schematic plan view of a fuel cell separator showing a state of water droplets generated in a gas flow path of a general fuel cell separator, and FIGS. FIG. 3 is a partially enlarged schematic plan view of a fuel cell separator showing a state of water droplets generated in a gas flow path of the fuel cell separator according to the present embodiment.

  In a general fuel cell separator, as shown in FIG. 5A, the water droplet 32 tends to stay at the tip of the gas flow path 34 or the rib 36. However, as shown in FIG. 5B, in the fuel cell separator according to this embodiment, the rib end portion 31a facing the gas outlet side manifold 20a is formed narrower than the rib main body portion 31b. The flow path width of the gas flow path 26a facing the gas outlet side manifold 20a can be widened, and even if water droplets stay in the gas flow path 26a, the gas flow path 26a can be prevented from being blocked. Further, since the rib end portion 31a is formed narrowly, it is difficult for water droplets to be held at the tip of the rib end portion 31a, and it is easy to drain water droplets to the gas outlet side manifold 20a. Further, as shown in FIG. 5 (c), by forming the rib end portion 31a narrower toward the gas outlet side manifold 20a, water droplets adhering to the tip of the rib end portion 31a are drained to the gas outlet side manifold 20a. It can be made easy.

  The separator for a fuel cell of the present embodiment may be subjected to a hydrophilic treatment in that drainage can be improved. Examples of the hydrophilic treatment include, in the case of carbon separators, known surface modification methods such as plasma treatment, UV treatment, and mixed gas treatment of fluorine and oxygen. Examples of the hydrophilic treatment of the metal separator include known coating methods such as a die coater method, a screen printing method, a doctor blade method, and a spray method using a solution or slurry of a hydrophilic material or a hydrophilic resin.

  FIG. 6 is a partially enlarged schematic plan view of an anode electrode separator according to another embodiment of the present invention. As shown in FIG. 6, the ribs 30 are preferably formed intermittently. As shown in FIG. 6, the rib 30 has the rib main body portion 31b formed intermittently, but the rib end portion 31a or both the rib end portion 31a and the rib main body portion 31b are formed intermittently. May be. The cathode side is preferably formed in the same manner.

  Usually, when one of the divided gas flow paths is blocked by a water droplet, the reaction gas hardly flows in the closed gas flow path. However, since the ribs 30 are intermittently formed as in the present embodiment, the communication path 40 that connects the adjacent anode gas flow paths 26 is formed, and therefore a part of the anode gas flow path 26 (for example, the anode gas) Even when one of the flow paths 26 is blocked by water droplets, the reaction gas flows to the communication path 40. Therefore, even if a part of the gas flow path is blocked by water droplets, it is possible to suppress a decrease in the performance of the fuel cell.

  The length of the intermittent portion of the rib 30 formed intermittently (L shown in FIG. 6) can reduce the amount of water accumulated in the gas flow path, and even when the flow rate of the reaction gas flowing through the gas flow path is small, The smaller one is preferable at the point which can make a water droplet drain easily. Moreover, the number of intermittent parts should just be at least 1 or more.

  FIG. 7 is a partially enlarged schematic plan view of an anode electrode separator according to another embodiment of the present invention. As shown in FIG. 7, a rib end portion 31 a formed narrower than the rib main body portion 31 b (illustrating the rib end portion 31 a facing the anode gas outlet side manifold 20) projects into the anode gas outlet side manifold 20. Preferably it is.

  As described above, by causing the rib end portion 31 a to protrude into the anode gas outlet side manifold 20, water droplets adhering to the rib end portion 31 a can be easily drained to the anode gas outlet side manifold 20. Thereby, the drainage of the anode gas channel 26 can be improved, and the blockage of the anode gas channel 26 can be suppressed. Also on the cathode electrode separator 14 side, it is preferable that a rib end formed narrower than the rib main body protrudes into the cathode gas outlet side manifold 24. Thereby, the drainage of the cathode gas channel 28 can be improved, and the blocking of the cathode gas channel 28 can be suppressed.

  FIG. 8 is a partially enlarged schematic plan view of an anode electrode separator according to another embodiment of the present invention. As shown in FIG. 8, even when the ribs 30 are intermittently formed, the rib end portion 31a facing the anode gas outlet side manifold 20 can be easily drained to the anode gas outlet side manifold 20. It is preferable to project into the gas outlet side manifold 20. Similarly, on the cathode separator 14 side, it is preferable that the rib end portion of the rib formed intermittently (the rib end portion facing the cathode gas outlet side manifold 24) protrudes into the cathode gas outlet side manifold.

  Another configuration of the fuel cell according to the present embodiment will be described.

  The anode electrode and the cathode electrode constituting the membrane-electrode assembly 10 each have a diffusion layer and a catalyst layer. The catalyst layer is, for example, formed by mixing carbon carrying a metal catalyst such as platinum or ruthenium with a perfluorosulfonic acid electrolyte or the like on the electrolyte membrane. Examples of the carbon include carbon black such as acetylene black, furnace black, channel black, and thermal black. The diffusion layer is not particularly limited as long as it is a material having a high reaction gas diffusibility. Examples thereof include porous carbon materials such as carbon cloth and carbon paper.

  The electrolyte membrane used in the present embodiment is not particularly limited as long as it does not have electron transfer properties but has proton conductivity. For example, a perfluorosulfonic acid resin film, a copolymer film of a trifluorostyrene derivative, a polybenzimidazole film impregnated with phosphoric acid, an aromatic polyether ketone sulfonic acid film, and the like can be given. Specific examples include Nafion (registered trademark).

  The sealing plate 16 functions as a gas leakage prevention for the reaction gas flowing through the gas flow path, a bonding point between the fuel cell separator and the adjacent member, and the like. The material constituting the sealing plate 16 is not particularly limited as long as it does not easily corrode in the environment of the fuel cell. For example, a polyolefin resin such as polyethylene and polypropylene, polyethylene terephthalate, polypropylene terephthalate, and the like. Resins such as polyester resins, engineering plastic resins such as polyphenylene sulfide, polyphenylene ether, and polyphenylene oxide, metals such as stainless steel and titanium, and the like can be used.

  The fuel cell of this embodiment may be a stacked body in which a plurality of the above-described fuel cells are used as unit cells. Moreover, in the case of a laminated body, it is preferable that the laminated body is placed vertically so that the gas outlet side manifold of the fuel cell separator is positioned below the gravity direction. As a result, the reaction gas discharged to the gas outlet side manifold is directed downward in the gravity direction, and water contained in the reaction gas is easily dropped by gravity along the narrowly formed rib. Therefore, water droplets in the gas flow path can be easily discharged to the gas outlet side manifold.

  As described above, in the fuel cell according to the present embodiment, the rib end facing the gas outlet side manifold is formed narrower than the rib main body, in particular, at least the rib end is at the gas outlet side manifold. By being formed so narrow that it goes to, it can improve the drainage nature of a gas channel, and it can control that a gas channel is obstructed by a water drop. In addition, since the ribs are intermittently formed, a communication path that connects adjacent gas flow paths is formed, so that even if a part of the gas flow path is blocked, the reaction gas flow is prevented from being hindered. can do. Furthermore, by allowing the rib end portion to protrude into the gas outlet side manifold, it is possible to improve the drainage of the gas flow path and to suppress the blockage of the gas flow path.

  The fuel cell according to the present embodiment can be used as, for example, a small power source for mobile devices such as a mobile phone and a portable personal computer, a power source for automobiles, and a household power source.

1 is a partial schematic cross-sectional view showing an example of a configuration of a fuel cell according to an embodiment of the present invention. It is a schematic plan view which shows an example of a structure of the separator for fuel cells which concerns on embodiment of this invention. FIG. 3 is a partially enlarged schematic plan view of an anode separator in a dotted frame R in FIG. FIG. 3 is a partially enlarged schematic plan view of an anode separator in a dotted frame R in FIG. (A) is a partially enlarged schematic plan view of an anode electrode separator showing a state of water droplets generated in a gas flow path of a general fuel cell separator, and (B) and (C) are in the present embodiment. It is a partially expanded schematic plan view of the anode electrode separator showing the state of water droplets generated in the gas flow path of the fuel cell separator. It is a partially expanded schematic plan view of an anode electrode separator according to another embodiment of the present invention. It is a partially expanded schematic plan view of an anode electrode separator according to another embodiment of the present invention. It is a partially expanded schematic plan view of an anode electrode separator according to another embodiment of the present invention. It is a schematic plan view which shows the structure of the conventional separator for fuel cells.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Fuel cell, 10 Membrane-electrode assembly, 12 Anode electrode separator, 13 Adhesive, 14 Cathode electrode separator, 16 Sealing plate, 18 Anode gas inlet side manifold, 20 Anode gas outlet side manifold, 20a Gas outlet side manifold, 22 Cathode Gas inlet side manifold, 24 Cathode gas outlet side manifold, 26 Anode gas flow path, 26a Gas flow path, 28 Cathode gas flow path, 30 Rib, 31a Rib end, 31b Rib body part, 32 Water droplet, 34 Gas flow path, 36 rib, 40 communication path, 50 fuel cell separator, 52 gas flow path, 54a anode gas inlet side manifold, 54b anode gas outlet side manifold, 54c cathode gas inlet side manifold, 54d cathode gas outlet side manifold Hold, 56 ribs.

Claims (6)

A fuel cell separator having a gas inlet side manifold and a gas outlet side manifold, a gas flow path communicating with the gas inlet side manifold and the gas outlet side manifold, and a rib dividing the gas flow path into a plurality of parts. There,
A fuel cell separator, wherein an end of a rib facing the gas outlet side manifold is formed narrower than a main body of the rib.   2. The fuel cell separator according to claim 1, wherein at least an end portion of the rib is formed so as to be narrower toward the gas outlet side manifold.   3. The fuel cell separator according to claim 1, wherein the rib is formed intermittently.   The fuel cell separator according to any one of claims 1 to 3, wherein an end portion of the rib projects into the gas outlet side manifold. A fuel cell separator having a gas inlet side manifold and a gas outlet side manifold, a gas flow path communicating with the gas inlet side manifold and the gas outlet side manifold, and a rib dividing the gas flow path into a plurality of parts. There,
An end of a rib facing the gas outlet manifold is formed so as to widen the width of the gas flow path. A fuel cell having a pair of fuel cell separators sandwiching a membrane-electrode assembly, wherein at least one of the fuel cell separators includes a gas inlet side manifold and a gas outlet side manifold, the gas inlet side manifold and the gas A gas flow path communicating with the outlet side manifold and a rib dividing the gas flow path into a plurality of parts are formed,
An end portion of a rib facing the gas outlet side manifold is formed narrower than a main body portion of the rib.

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