JP2006100016A - Fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to surely prevent condensed water from being collected in a reaction gas communicating hole and secure excellent power generating performance in a simple and economical structure. <P>SOLUTION: The fuel cell stack is provided with a laminated body 14 with a plurality of laminated fuel cells 12, and an oxidant gas outlet communicating hole 40b is formed by penetrating the laminated body 14 in a lamination direction. At a bottom of the oxidant gas outlet communicating hole 40b, an insertion member 68a is arranged with an interposition of a rubber member 66a. The insertion member 68a is structured long in the lamination direction, and has a plurality of slanted groove parts 70a slanted toward a flowing direction of exhaust oxidant gas in the oxidant gas outlet communicating hole 40b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention includes an electrolyte / electrode structure in which a pair of electrodes are provided on both sides of an electrolyte, and a laminate in which a separator is stacked in a horizontal direction, and the electrolyte / electrode structure is interposed between the separator and one separator. The reaction gas flow path for supplying the reaction gas is formed along the surface direction of the electrode, and the reaction gas communication hole communicating with the end of the reaction gas flow path penetrates the stacked body in the stacking direction. The internal manifold type fuel cell stack is formed.

  For example, a solid polymer fuel cell employs a solid polymer electrolyte membrane made of a polymer ion exchange membrane. This fuel cell has an electrolyte membrane / electrode structure in which an anode side electrode and a cathode side electrode each made of an electrode catalyst (electrode catalyst layer) and porous carbon (diffusion layer) are provided on both sides of a solid polymer electrolyte membrane. A power generation cell sandwiched between separators (bipolar plates) is formed. Usually, in a fuel cell, a fuel cell stack in which a predetermined number of power generation cells are stacked is used.

  In this type of fuel cell, the anode side electrode is supplied with a fuel gas (reactive gas), for example, a gas mainly containing hydrogen (hereinafter also referred to as hydrogen-containing gas), while the cathode side electrode An oxidant gas (reactive gas), for example, a gas mainly containing oxygen or air (hereinafter also referred to as oxygen-containing gas) is supplied. In the fuel gas supplied to the anode side electrode, hydrogen is ionized on the electrode catalyst and moves to the cathode side electrode side through the electrolyte membrane. Electrons generated during that time are taken out to an external circuit and used as direct current electric energy.

  In the above fuel cell, an internal manifold is often configured to supply a fuel gas and an oxidant gas, which are reaction gases, to the anode side electrode and the cathode side electrode of each of the stacked power generation cells. The internal manifold includes a reaction gas inlet communication hole and a reaction gas outlet communication hole provided so as to penetrate in the stacking direction of the power generation cells, and a reaction gas flow path (oxidant gas) for supplying the reaction gas along the electrode surface. The reaction gas inlet communication hole and the reaction gas outlet communication hole communicate with the inlet side end and the outlet side end of the flow path and the fuel gas flow path, respectively.

  By the way, reaction product water generated during power generation is introduced into the oxidant gas outlet communication hole through which the oxidant gas flows in the stacking direction and the oxidant gas communication hole (reaction gas communication hole) which is the oxidant gas inlet communication hole. It is easy and there may be a case where stagnant water exists in the oxidant gas communication hole. On the other hand, there is a possibility that stagnant water due to condensation or the like may be generated in the fuel gas outlet communication hole through which the fuel gas flows in the stacking direction or the fuel gas communication hole (reaction gas communication hole) which is the fuel gas inlet communication hole. Accordingly, there is a problem that the oxidant gas communication hole and the fuel gas communication hole are easily reduced or blocked by the staying water, and the flow of the oxidant gas and the fuel gas is hindered to reduce the power generation performance.

  Therefore, for example, as shown in FIG. 7, the fuel cell stack disclosed in Patent Document 1 stacks a plurality of cells 1, and the stacked body of the plurality of cells 1 is connected to both ends by a pair of end plates 2. Is pinched. One end plate 2 is connected to a gas supply pipe 3 for supplying fuel gas or oxidant gas and a gas exhaust pipe 4 for discharging the fuel gas or oxidant gas.

  The gas supply pipe 3 and the gas exhaust pipe 4 are provided with a water reservoir portion 5 for temporarily storing condensed water and generated water, and a drain pipe 7 is connected to the lower portion of the water reservoir portion 5 through an electromagnetic valve 6. Has been.

  An internal manifold 9 is formed in a fuel cell stack 8 in which a plurality of cells 1 are sandwiched between a pair of end plates 2. The inner manifold 9 has an inclined bottom surface by gradually widening the hole diameter toward the gas supply pipe 3 and the gas exhaust pipe 4. Thereby, the condensed water and generated water of the internal manifold 9 smoothly flow to the respective water reservoirs 5 along the inclination of the lower surface of the internal manifold 9, and the water of the water reservoir 5 drains under the action of the electromagnetic valve 6. It is assumed that the gas is discharged through the pipe 7.

Japanese Patent Laying-Open No. 2003-177871 (FIG. 3)

  However, in Patent Document 1 described above, an electromagnetic valve 6 is connected below each water reservoir 5, and control of the electromagnetic valve 6 is required, which complicates the entire system. As a result, there is a problem that the cost of the entire system increases and the reliability decreases.

  In addition, the internal manifold 9 that expands toward each water reservoir 5 side is formed across a stacked body of a plurality of cells 1, and the formation work of the internal manifold 9 becomes complicated, and each cell 1 has a different configuration. have. For this reason, there is a problem that the cost of the entire system is considerably increased and the handling of each cell 1 becomes complicated.

  The present invention solves this type of problem, and with a simple and economical configuration, it is possible to reliably prevent the condensate from staying in the reaction gas communication hole and to ensure good power generation performance. An object of the present invention is to provide a fuel cell stack capable of satisfying the requirements.

  The present invention includes an electrolyte / electrode structure in which a pair of electrodes are provided on both sides of an electrolyte, and a laminate in which a separator is stacked in a horizontal direction, and the electrolyte / electrode structure is interposed between the separator and one separator. The reaction gas flow path for supplying the reaction gas is formed along the surface direction of the electrode, and the reaction gas communication hole communicating with the end of the reaction gas flow path penetrates the stacked body in the stacking direction. It is an internal manifold type fuel cell stack formed as described above. An inclined groove portion that is inclined toward the flow direction of the reaction gas in the reaction gas communication hole is formed on the bottom wall surface constituting the bottom of the reaction gas communication hole.

  Further, it is preferable that an insertion member disposed at the bottom of the reaction gas communication hole is provided, and an inclined groove is formed on the upper surface of the insertion member. Furthermore, it is preferable that the insertion member is made of a resin, and a plurality of inclined groove portions are formed on the insertion member so as to be spaced apart from each other at predetermined intervals and substantially parallel to each other. Furthermore, it is preferable that the end portion of the reaction gas flow path is at least a reaction gas supply side end portion or a reaction gas discharge side end portion opened to the side portion of the reaction gas communication hole.

  According to the present invention, the condensed water (including generated water) discharged to the reaction gas communication hole moves smoothly and reliably along the inclined groove portion and does not stay at the bottom of the reaction gas communication hole. As a result, the reaction gas communication hole is not blocked by the accumulated water, and a stable power generation voltage can be reliably obtained with a simple configuration.

  FIG. 1 is a schematic perspective view of a fuel cell stack 10 according to an embodiment of the present invention.

  The fuel cell stack 10 includes a stacked body 14 in which a plurality of fuel cells 12 are stacked. At both ends of the stacked body 14 in the stacking direction (arrow A direction), first and second terminal plates 16a and 16b, First and second insulating plates 18a and 18b and first and second end plates 20a and 20b are sequentially provided. Although not shown, the fuel cell stack 10 is clamped and held by, for example, a tightening bolt or a box-shaped casing.

  As shown in FIG. 2, the fuel cell 12 includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) 22 stacked in a horizontal direction (arrow A direction), first and second metal separators 24, 26, Is provided. Instead of the first and second metal separators 24 and 26, for example, a carbon separator may be used.

  The electrolyte membrane / electrode structure 22 includes, for example, a solid polymer electrolyte membrane 28 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode side electrode 30 and a cathode side electrode 32 that sandwich the solid polymer electrolyte membrane 28. With. The anode side electrode 30 and the cathode side electrode 32 are uniformly coated on the surface of the gas diffusion layer with a gas diffusion layer (not shown) made of carbon paper or the like and porous carbon particles carrying a platinum alloy on the surface. An electrode catalyst layer (not shown).

  One end edge of the fuel cell 12 in the direction of arrow B communicates with each other in the direction of arrow A, which is the stacking direction, and an oxidant gas inlet communication hole (reactive gas) for supplying an oxidant gas, for example, an oxygen-containing gas. A communication hole) 40a, a cooling medium inlet communication hole 42a for supplying a cooling medium, and a fuel gas outlet communication hole (reactive gas communication hole) 44b for discharging a fuel gas, for example, a hydrogen-containing gas, are provided in the direction of arrow C. They are arranged in the (vertical direction).

  The other end edge of the fuel cell 12 in the direction of arrow B communicates with each other in the direction of arrow A, a fuel gas inlet communication hole (reaction gas communication hole) 44a for supplying fuel gas, and for discharging the cooling medium. The cooling medium outlet communication holes 42b and the oxidant gas outlet communication holes (reaction gas communication holes) 40b for discharging the oxidant gas are arranged in the direction of arrow C.

  An oxidant gas flow path (reactive gas flow path) 46 is provided on the surface 24 a of the first metal separator 24 facing the electrolyte membrane / electrode structure 22. The oxidant gas flow channel 46 includes a plurality of oxidant gas flow channel grooves 46a, and the oxidant gas flow channel groove 46a extends in the direction of arrow B. The oxidant gas channel groove 46a may constitute, for example, a serpentine channel groove that is folded back and forth by one reciprocal half in the arrow B direction.

  A fuel gas channel (reactive gas channel) 48 is provided on the surface 26 a of the second metal separator 26 facing the electrolyte membrane / electrode structure 22. Similar to the oxidant gas flow path 46, the fuel gas flow path 48 has a plurality of fuel gas flow path grooves 48 a extending in the arrow B direction.

  The first metal separator 24 and the second metal separator 26 integrally form a cooling medium flow path 50 on the surfaces 24b and 26b facing each other. The cooling medium flow path 50 is formed integrally with the back surface side of the oxidant gas flow path 46 and the back surface side of the fuel gas flow path 48, and has a plurality of cooling medium flow path grooves 50a extending in the arrow B direction. . The cooling medium flow path 50 communicates with the cooling medium inlet communication hole 42a and the cooling medium outlet communication hole 42b.

  On the surfaces 24a and 24b of the first metal separator 24, a first seal member 54 is integrally provided around the outer peripheral edge portion of the first metal separator 24 by injection molding or the like. The first seal member 54 covers the oxidant gas inlet communication hole 40a, the oxidant gas outlet communication hole 40b, and the oxidant gas flow path 46 on the surface 24a to prevent leakage of the oxidant gas.

  On the surfaces 26a and 26b of the second metal separator 26, a second seal member 56 is integrally provided around the outer peripheral edge of the second metal separator 26 by injection molding or the like. The second seal member 56 covers the fuel gas inlet communication hole 44a, the fuel gas outlet communication hole 44b, and the fuel gas flow path 48 on the surface 26a, and performs fuel gas leakage prevention. The second seal member 56 covers the cooling medium inlet communication hole 42a, the cooling medium outlet communication hole 42b, and the cooling medium flow path 50 on the surface 26b, and performs leakage prevention of the cooling medium.

  As shown in FIG. 3, the wall surface forming the oxidant gas outlet communication hole 40b is provided with a guide curved wall surface 60a on the upper side of the oxidant gas outlet communication hole 40b, and the oxidant gas flow A recess 62a is formed projecting downward from the path 46. Similarly to the oxidant gas outlet communication hole 40b, the fuel gas outlet communication hole 44b is provided with a curved wall surface 60b and a recess 62b on the wall portion.

  In the oxidant gas outlet communication hole 40b and the fuel gas outlet communication hole 44b, insertion members 68a and 68b are disposed at the bottoms 64a and 64b with rubber members 66a and 66b interposed therebetween. The rubber members 66a and 66b are made of, for example, EPDM (ethylene propylene rubber), and are provided on the back side of the insertion members 68a and 68b that are long in the stacking direction of the stacked body 14, as shown in FIG.

  The insertion members 68a and 68b are made of a resin material, for example, PPS (polyphenylene sulfide), and a plurality of inclined groove portions 70a and 70b are formed by cutting or the like. As shown in FIG. 4, the inclined groove portions 70 a and 70 b are formed in a trapezoidal cross-section that expands upward, and as shown in FIG. 5, an oxidizing agent is applied to the perpendicular T that extends in the direction of arrow B. It is inclined by an angle θ ° in the flow direction of the exhaust oxidant gas (the direction of arrow A1) in the gas outlet communication hole 40b.

  The angle θ ° is set within a range of 2 ° to 45 °. In the present embodiment, for example, θ ° = 5 ° is set. The distance H between the inclined groove portions 70a and between the inclined groove portions 70b is preferably set within a range of 1 mm to 20 mm.

  The oxidant gas inlet communication hole 40a and the fuel gas inlet communication hole 44a may be configured similarly to the oxidant gas outlet communication hole 40b and the fuel gas outlet communication hole 44b as necessary.

  The operation of the fuel cell stack 10 configured as described above will be described below.

  As shown in FIG. 1, in the first end plate 20a constituting the fuel cell stack 10, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 40a and the fuel gas inlet communication hole 44a. Fuel gas such as hydrogen-containing gas is supplied. Further, a cooling medium such as pure water or ethylene glycol is supplied to the cooling medium inlet communication hole 42a.

  As shown in FIG. 2, the oxidant gas is introduced into the oxidant gas flow path 46 of the first metal separator 24 from the oxidant gas inlet communication hole 40a. In the oxidant gas flow path 46, the oxidant gas is dispersed in the plurality of oxidant gas flow path grooves 46a. Therefore, the oxidant gas moves along the cathode side electrode 32 of the electrolyte membrane / electrode structure 22 through each oxidant gas flow channel groove 46a.

  On the other hand, the fuel gas is introduced into the fuel gas channel 48 of the second metal separator 26 from the fuel gas inlet communication hole 44a. In the fuel gas channel 48, the fuel gas is dispersed in the plurality of fuel gas channel grooves 48a. Further, the fuel gas moves along the anode side electrode 30 of the electrolyte membrane / electrode structure 22 through each fuel gas flow channel 48a.

  Therefore, in the electrolyte membrane / electrode structure 22, the oxidant gas supplied to the cathode side electrode 32 and the fuel gas supplied to the anode side electrode 30 are consumed by an electrochemical reaction in the electrode catalyst layer, thereby generating power. Is done.

  Next, the oxidant gas consumed by being supplied to the cathode side electrode 32 is discharged to the oxidant gas outlet communication hole 40b (see FIGS. 1 and 2). Similarly, the fuel gas supplied to and consumed by the anode side electrode 30 is discharged to the fuel gas outlet communication hole 44b.

  On the other hand, the cooling medium supplied to the cooling medium inlet communication hole 42a is introduced into the cooling medium flow path 50 formed between the first and second metal separators 24 and 26 (see FIG. 2). In the cooling medium flow path 50, the cooling medium moves in the horizontal direction (arrow B direction). Therefore, the cooling medium is cooled over the entire power generation surface of the electrolyte membrane / electrode structure 22 and then discharged to the cooling medium outlet communication hole 42b.

  In this case, in the present embodiment, as shown in FIG. 3, for example, an insertion member 68a is disposed on the bottom 64a of the oxidizing gas outlet communication hole 40b via a rubber member 66a. As shown in FIGS. 1 and 5, the insertion member 68 a is formed with a plurality of inclined groove portions 70 a that are inclined in the flow direction of the discharged oxidant gas (direction of arrow A <b> 1) in the oxidant gas outlet communication hole 40 b. Yes.

  For this reason, moisture (product water or the like) discharged from the discharge side end of the oxidant gas flow path 46 to the oxidant gas outlet communication hole 40b moves smoothly and reliably along each inclined groove part 70a of the insertion member 68a. (Refer to the broken line arrow in FIG. 5), and it is discharged well from the oxidant gas outlet communication hole 40b.

  Accordingly, in this embodiment, no accumulated water is generated in the oxidant gas outlet communication hole 40b, and the oxidant gas outlet communication hole 40b is not clogged by the accumulated water. Therefore, it is possible to obtain a stable power generation voltage with a simple configuration.

  Here, an experiment for comparing drainage performance using a fuel cell stack (comparative example) in which the insertion member 68a is not provided in the oxidant gas outlet communication hole 40b and a fuel cell stack (example) in which the insertion member 68a is provided. Went. Specifically, a predetermined amount of pure water is added from the oxidant gas inlet communication hole 40a of each fuel cell stack, and nitrogen scavenging is performed from the oxidant gas inlet communication hole 40a and the fuel gas inlet communication hole 44a. When the change in the weight of the fuel cell stack was detected, the results shown in FIG. 6 were obtained. As can be seen from FIG. 6, a larger amount of water was discharged in the example than in the comparative example.

  Moreover, as shown in FIG. 3, the oxidant gas outlet communication hole 40b is provided with a curved wall surface 60a on the upper side. For this reason, the used oxidant gas discharged from the oxidant gas flow path 46 to the oxidant gas outlet communication hole 40b can smoothly flow downward, and accordingly moisture is inserted into the insertion member 68a side. There is an advantage that it can be moved well.

  Further, a recess 62 a is provided so as to protrude below the oxidizing gas channel 46. Therefore, the used oxidant gas and moisture moved to the lower side of the oxidant gas outlet communication hole 40 b are favorably prevented from flowing back into the oxidant gas flow path 46.

  The fuel gas outlet communication hole 44b provides the same effect as the oxidant gas outlet communication hole 40b.

  Further, in the oxidant gas outlet communication hole 40b and the fuel gas outlet communication hole 44b, insertion members 68a and 68b are disposed at the bottom portions 64a and 64b with rubber members 66a and 66b interposed therebetween. It is not limited to. For example, the insertion members 68a and 68b may be disposed directly on the bottom portions 64a and 64b without using the rubber members 66a and 66b, or the inclined groove portions 70a and 70b may be formed directly on the bottom portions 64a and 64b. Good.

1 is a schematic perspective view of a fuel cell stack according to an embodiment of the present invention. It is a disassembled perspective view of the fuel cell which comprises the said fuel cell stack. It is front explanatory drawing of the 1st metal separator which comprises the said fuel cell. It is a partially expanded explanatory view of the insertion member which comprises the said fuel cell stack. It is a plane explanatory view of the insertion member. It is explanatory drawing of the weight change by a comparative example and an Example. 2 is a schematic explanatory diagram of a fuel cell stack of Patent Document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell stack 12 ... Fuel cell 22 ... Electrolyte membrane and electrode structure 24, 26 ... Metal separator 28 ... Solid polymer electrolyte membrane 30 ... Anode side electrode 32 ... Cathode side electrode 40a ... Oxidant gas inlet communication hole 40b ... Oxidant gas outlet communication hole 42a ... Cooling medium inlet communication hole 42b ... Cooling medium outlet communication hole 44a ... Fuel gas inlet communication hole 44b ... Fuel gas outlet communication hole 46 ... Oxidant gas channel 46a ... Oxidant gas channel groove 48 ... fuel gas passage 48a ... fuel gas passage groove 50 ... cooling medium passages 60a, 60b ... curved wall surfaces 62a, 62b ... concave portions 64a, 64b ... bottom portions 66a, 66b ... rubber members 68a, 68b ... insertion members 70a, 70b ... Inclined groove

Claims (4)

An electrolyte / electrode structure in which a pair of electrodes are provided on both sides of the electrolyte, and a laminate in which a separator is stacked in a horizontal direction, and the electrode / electrode structure is disposed between the electrolyte / electrode structure and one separator. A reaction gas flow path for supplying a reaction gas along the surface direction is formed, and a reaction gas communication hole communicating with an end of the reaction gas flow path is formed through the stacked body in the stacking direction. An internal manifold type fuel cell stack,
A fuel cell stack, wherein an inclined groove portion that is inclined toward a flow direction of the reaction gas in the reaction gas communication hole is formed on a bottom wall surface constituting a bottom portion of the reaction gas communication hole. The fuel cell stack according to claim 1, further comprising an insertion member disposed at a bottom of the reaction gas communication hole,
The fuel cell stack, wherein the inclined groove is formed on an upper surface of the insertion member. The fuel cell stack according to claim 2, wherein the insertion member is made of resin.
The fuel cell stack, wherein the insertion member includes a plurality of the inclined groove portions spaced apart from each other by a predetermined interval and substantially parallel to each other. 4. The fuel cell stack according to claim 1, wherein an end portion of the reaction gas flow path is at least a reaction gas supply side end portion or a reaction gas opened to a side portion of the reaction gas communication hole. A fuel cell stack which is a discharge side end.

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