JP2006092991A - Fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To intend to enhance starting performance in low temperatures in particular while obtaining a stable power generating voltage with a simple structure, by surely preventing water from staying in a reacting gas communicating hole. <P>SOLUTION: This fuel cell stack 10 is equipped with a laminate 14 in which a plurality of fuel cells 12 are laminated, and an inside manifold is formed by penetrating through the laminate 4 in the laminating direction. One end side of an oxidizer gas exit communicating hole 36b in the laminated direction is opened to the first end plate 20b side, and the other end side of the oxidizer gas exit communicating hole 36b in the laminated direction is blocked on the second end plate 20b side. A second insulating plate 18b having a curved part 70 in communication with the oxidizer gas exit communicating hole 36b is disposed on the other end side in the laminating direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell stack that includes an electrolyte / electrode structure in which a pair of electrodes are provided on both sides of an electrolyte, and a laminate in which separators are laminated in a horizontal direction, and constitutes an internal manifold.

  For example, a solid polymer fuel cell employs a solid polymer electrolyte membrane made of a polymer ion exchange membrane. This fuel cell is an electrolyte membrane / electrode structure in which an anode side electrode and a cathode side electrode made of an electrode catalyst (electrode catalyst layer) and porous carbon (gas diffusion layer) are provided on both sides of a solid polymer electrolyte membrane, respectively. Is constituted by a power generation cell sandwiched between separators (bipolar plates). 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 that are provided so as to penetrate in the stacking direction of the power generation cells, and an inlet side of the reaction gas flow path 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 outlet side.

  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. 8, 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 sandwiched at both ends by end plates 2. Has been. The 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 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 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 back side of the internal manifold 9 (the side opposite to the reaction gas inlet / outlet) is closed, and a water pool tends to occur on the back side. Therefore, even if the lower surface of the internal manifold 9 is provided with an inclination, there is a possibility that the water staying at the back side of the internal manifold 9 cannot be discharged well to the water reservoir 5. As a result, the stability of the power generation voltage of the fuel cell stack 8 is lowered, and in particular, there is a problem that the internal manifold 9 is blocked during a low temperature start.

  The present invention solves this type of problem, reliably prevents the generation of stagnant water at the back of the reaction gas communication hole, obtains a stable power generation voltage with a simple configuration, and particularly at a low temperature start. An object of the present invention is to provide a fuel cell stack capable of improving the performance.

  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 laminated in a horizontal direction, and the electrolyte / electrode structure is interposed between the electrolyte / electrode structure and one separator. Is formed with a reaction gas flow path for supplying a reaction gas along a surface direction of the electrode, and communicates with a supply side end or a discharge side end of the reaction gas flow path to stack the stacked body in the stacking direction. This is an internal manifold type fuel cell stack in which a reaction gas communication hole penetrating through is formed.

  The reactive gas communication hole has one end in the stacking direction opened and the other end in the stacking direction closed, and at the other end in the stacking direction, an end member having a curved portion communicating with the reactive gas communication hole at least on the lower side Is arranged.

  The end member is preferably at least one of a terminal plate, an insulating plate, and an end plate that are stacked on the stacked body. This is because the configuration can be easily simplified.

  Furthermore, it is preferable that the bending portion is provided on a loading member disposed on the end member. This is because the shape of the end member is effectively simplified, and the insulating property of the end member can be favorably maintained by configuring the loading member with an insulating member.

  According to the present invention, the condensed water (including generated water) discharged to the other end of the reaction gas communication hole in the stacking direction moves smoothly and reliably along at least the curved portion provided on the lower side, It does not stay at the other end in the direction. For this reason, the condensed water is discharged to one end side in the stacking direction through the reaction gas communication hole communicating with the curved portion. As a result, the reaction gas communication hole is not clogged with stagnant water, and it is possible to obtain a stable power generation voltage with a simple configuration and to improve the low temperature startability.

  FIG. 1 is a schematic perspective view of a fuel cell stack 10 according to a first embodiment of the present invention, and FIG. 2 is a partial sectional side view of the fuel cell stack 10.

  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. 3, the fuel cell 12 includes an electrolyte membrane / electrode structure 30, and first and second metal separators 32, 34 having a thin plate shape that sandwich the electrolyte membrane / electrode structure 30. Instead of the first and second metal separators 32 and 34, for example, a carbon separator may be adopted.

  An oxidant gas inlet communication hole (reactive gas communication hole) 36a for supplying an oxidant gas, for example, an oxygen-containing gas, communicates with each other in the arrow A direction at one end edge of the fuel cell 12 in the arrow B direction. A cooling medium inlet communication hole 38a for supplying a cooling medium and a fuel gas outlet communication hole (reaction gas communication hole) 40b for discharging a fuel gas, for example, a hydrogen-containing gas, are provided.

  The oxidant gas inlet communication hole 36a, the cooling medium inlet communication hole 38a, and the fuel gas outlet communication hole 40b are opened at one end in the stacking direction on the first end plate 20a side and the other end in the stacking direction on the second end plate 20b side. Is blocked.

  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) 40a for supplying fuel gas, and for discharging the cooling medium The cooling medium outlet communication hole 38b and the oxidant gas outlet communication hole (reaction gas communication hole) 36b for discharging the oxidant gas are provided.

  The fuel gas inlet communication hole 40a, the cooling medium outlet communication hole 38b, and the oxidant gas outlet communication hole 36b are opened at one end in the stacking direction on the first end plate 20a side, and the other end in the stacking direction on the second end plate 20b side. Is blocked.

  A fuel gas flow path (reactive gas flow path) 42 that connects the fuel gas inlet communication hole 40a and the fuel gas outlet communication hole 40b is formed on the surface 32a of the first metal separator 32 facing the electrolyte membrane / electrode structure 30. Is done. The fuel gas channel 42 is constituted by, for example, a plurality of grooves extending in the arrow B direction. A cooling medium flow path 44 that connects the cooling medium inlet communication hole 38 a and the cooling medium outlet communication hole 38 b is formed on the surface 32 b of the first metal separator 32. The cooling medium flow path 44 is constituted by a plurality of grooves extending in the arrow B direction.

  The surface 34a of the second metal separator 34 facing the electrolyte membrane / electrode structure 30 is provided with, for example, an oxidant gas channel (reactive gas channel) 46 including a plurality of grooves extending in the direction of arrow B. At the same time, the oxidant gas flow path 46 communicates with the oxidant gas inlet communication hole 36a and the oxidant gas outlet communication hole 36b. A cooling medium flow path 44 is integrally formed on the surface 34 b of the second metal separator 34 so as to overlap the surface 32 b of the first metal separator 32.

  A first seal member 48 is integrally formed on the surfaces 32 a and 32 b of the first metal separator 32 around the outer peripheral end portion of the first metal separator 32. The first seal member 48 surrounds and communicates the fuel gas inlet communication hole 40a, the fuel gas outlet communication hole 40b, and the fuel gas flow path 42 with the surface 32a, while the surface 32b communicates with the cooling medium inlet communication hole 38a. The medium outlet communication hole 38b and the cooling medium flow path 44 are surrounded and communicated with each other.

  A second seal member 50 is integrally formed on the surfaces 34 a and 34 b of the second metal separator 34 around the outer peripheral end of the second metal separator 34. The second seal member 50 surrounds and communicates the oxidant gas inlet communication hole 36a, the oxidant gas outlet communication hole 36b, and the oxidant gas flow path 46 at the surface 34a, while the cooling medium inlet communication hole at the surface 34b. 38a, the cooling medium outlet communication hole 38b, and the cooling medium flow path 44 are surrounded and communicated with each other.

  The electrolyte membrane / electrode structure 30 includes, for example, a solid polymer electrolyte membrane 52 in which a thin film of perfluorosulfonic acid is impregnated with water, and an anode side electrode 54 and a cathode side electrode 56 that sandwich the solid polymer electrolyte membrane 52. With.

  The anode side electrode 54 and the cathode side electrode 56 are uniformly coated 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 thereof. And an electrode catalyst layer (not shown) formed. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 52.

  As shown in FIG. 2, the first and second insulating plates 18a and 18b are made of an insulating material such as polyphenylene sulfide (PPS) or phenol resin. The first and second insulating plates 18a and 18b are provided with rectangular recesses 60a and 60b at the center, and the holes 62a and 62b communicate with the approximate center of the recesses 60a and 60b.

  The recesses 60a and 60b accommodate the first and second terminal plates 16a and 16b, and the terminal portions 64a and 64b of the first and second terminal plates 16a and 16b interpose the insulating cylinders 66a and 66b. Are inserted into the holes 62a and 62b. Holes 68a and 68b are formed coaxially with the holes 62a and 62b in the first and second end plates 20a and 20b.

  As shown in FIG. 4, the second insulating plate 18b, which is an end member, communicates with the oxidant gas outlet communication hole 36b corresponding to the other end in the stacking direction where the oxidant gas outlet communication hole 36b is closed. A curved portion 70 is formed. The curved portion 70 is formed so as to face the surface of the second insulating plate 18b, and R is provided over the entire circumference.

  This R is set within a range of 1.0 to 50, and more preferably within a range of 1.5 to 30. In consideration of the flow due to the weight of the condensed water, R may be provided at least on the lower side of the curved portion 70.

  As shown in FIG. 5, the second insulating plate 18b is formed with a curved portion 70a communicating with the fuel gas outlet communication hole 40b at the other end in the stacking direction where the fuel gas outlet communication hole 40b is closed. The second insulating plate 18b further includes the other end in the stacking direction where the oxidant gas inlet communication hole 36a is closed and the other end in the stacking direction where the fuel gas inlet communication hole 40a is closed as necessary. Curved portions 70b and 70c communicating with the oxidant gas inlet communication hole 36a and the fuel gas inlet communication hole 40a are formed.

  As shown in FIG. 1, pipe manifolds 72a and 78a communicating with the oxidant gas inlet communication hole 36a, the cooling medium inlet communication hole 38a, and the fuel gas outlet communication hole 40b on one end side in the arrow B direction are connected to the first end plate 20a. And 80b are attached via insulating grommets 82.

  On the other end side in the arrow B direction of the first end plate 20a, piping manifolds 80a, 78b and 72b communicating with the fuel gas inlet communication hole 40a, the cooling medium outlet communication hole 38b and the oxidant gas outlet communication hole 36b are insulated grommets 82. (See FIGS. 1 and 4). The piping manifolds 72b and 80b have inclined portions 84 that are inclined downward with respect to the horizontal direction (arrow A direction).

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

  First, as shown in FIG. 1, in the fuel cell stack 10, an oxidant gas such as an oxygen-containing gas is supplied from a pipe manifold 72a, and a fuel gas such as a hydrogen-containing gas is supplied from a pipe manifold 80a. Further, a cooling medium such as pure water or ethylene glycol is supplied from the piping manifold 78a. For this reason, oxidant gas, fuel gas, and a cooling medium are supplied to each fuel cell 12 in the direction of arrow A.

  As shown in FIG. 3, the oxidant gas is introduced from the oxidant gas inlet communication hole 36 a into the oxidant gas flow path 46 of the second metal separator 34, and along the cathode side electrode 56 of the electrolyte membrane / electrode structure 30. Move. On the other hand, the fuel gas is introduced into the fuel gas flow path 42 of the first metal separator 32 from the fuel gas inlet communication hole 40 a and moves along the anode side electrode 54 of the electrolyte membrane / electrode structure 30.

  Therefore, in each electrolyte membrane / electrode structure 30, the oxidant gas supplied to the cathode side electrode 56 and the fuel gas supplied to the anode side electrode 54 are consumed by an electrochemical reaction in the electrode catalyst layer, Power generation is performed (see FIG. 2).

  Next, the oxidant gas consumed by being supplied to the cathode-side electrode 56 flows in the direction of arrow A along the oxidant gas outlet communication hole 36b, and is then discharged to the pipe manifold 72b (see FIG. 1). Similarly, the fuel gas consumed by being supplied to the anode electrode 54 is discharged to the fuel gas outlet communication hole 40b, flows in the direction of arrow A, and is discharged to the pipe manifold 80b.

  Further, as shown in FIG. 3, the cooling medium is introduced into the cooling medium flow path 44 between the first and second metal separators 32 and 34 from the cooling medium inlet communication hole 38a, and then flows along the arrow B direction. To do. The cooling medium cools the electrolyte membrane / electrode structure 30, then moves through the cooling medium outlet communication hole 38 b and is discharged to the piping manifold 78 b (see FIG. 1).

  In this case, in the first embodiment, as shown in FIG. 4, one end of the oxidizing gas outlet communication hole 36b in the stacking direction on the first end plate 20a side is opened and the stacking direction on the second end plate 20b side is opened. The other end is closed. Furthermore, the second insulating plate (end member) 18b disposed at the other end in the stacking direction is formed with a curved portion 70 communicating with the oxidant gas outlet communication hole 36b.

  Water generated by the reaction tends to stay at the other end in the stacking direction where the oxidizing gas outlet communication hole 36b is closed. Therefore, by providing the curved portion 70 having R at the other end in the stacking direction, the generated water moves smoothly and reliably along the curved portion 70, and the generated water stays at the other end in the stacking direction. Can be prevented.

  Therefore, the generated water led out to the bending portion 70 moves to one end of the stack through the oxidizing gas outlet communication hole 36b communicating with the bending portion 70, and is discharged to the piping manifold 72b. As a result, the oxidant gas outlet communication hole 36b is not clogged with stagnant water, and a stable power generation voltage can be obtained with a simple configuration, and in particular, low temperature startability can be improved. The effect is obtained.

  Furthermore, R of the curved portion 70 is set within a range of 1.0 to 50, and more preferably within a range of 1.5 to 30. For this reason, it is possible to reliably prevent the generation of accumulated water, and the second insulating plate 18b is not thickened in the direction of arrow A, so that the entire fuel cell stack 10 can be downsized satisfactorily.

  The fuel gas outlet communication hole 40b, the oxidant gas inlet communication hole 36a, and the fuel gas inlet communication hole 40a are provided with curved portions 70a, 70b, and 70c having a predetermined R at the other end in the stacking direction. The same effect as the oxidant gas outlet communication hole 36b is obtained.

  FIG. 6 is a partial cross-sectional side view of a fuel cell stack 90 according to the second embodiment of the present invention. The same components as those of the fuel cell stack 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Similarly, in the third embodiment described below, detailed description thereof is omitted.

  In the fuel cell stack 90, a curved portion 92 is formed from the second insulating plate 18b to the second end plate 20b at least at the other end in the stacking direction where the oxidant gas outlet communication hole 36b is closed. The second insulating plate 18b and the second end plate 20b integrally constitute an end member, and the curved portion 92 having a predetermined R communicates with the oxidant gas outlet communication hole 36b. Here, R of the bending portion 92 is the same as R of the bending portion 70.

  In the second embodiment, a curved portion 92 is integrally provided from the second insulating plate 18b to the second end plate 20b at the other end in the stacking direction where the oxidizing gas outlet communication hole 36b is closed. The effect similar to 1st Embodiment is acquired, such as being able to prevent reliably that stagnant water generate | occur | produces in the lamination direction other end.

  Only the second end plate 20b may be an end member, and the curved portion 92 that communicates with the oxidant gas outlet communication hole 36b may be formed only on the second end plate 20b.

  FIG. 7 is a partial cross-sectional side view of a fuel cell stack 100 according to the third embodiment of the present invention.

  In the fuel cell stack 100, a recess 102 is formed in an end member, for example, the second end plate 20b, and a loading member 104 is disposed in the recess 102. The loading member 104 is formed with a curved portion 106 communicating with at least the oxidant gas outlet communication hole 36b, and the loading member 104 is formed of an insulating member.

  In the third embodiment configured as described above, the curved portion 106 communicates with the other end in the stacking direction of the oxidant gas outlet communication hole 36b, and stagnant water is prevented from being generated at the other end in the stacking direction. The same effects as those of the first and second embodiments can be obtained. In addition, by configuring the loading member 104 with an insulating member, there is an advantage that it is possible to maintain good insulation. Further, the loading member 104 may be used for the second insulating plate 18b.

  In the first to third embodiments, the second terminal plate 16b is accommodated in the recess 60b formed in the second insulating plate 18b. However, the present invention is not limited to this. The second terminal plate 16b and the second insulating plate 18b may have the same outer dimensions.

1 is a schematic perspective view of a fuel cell stack according to a first embodiment of the present invention. FIG. 3 is a cross-sectional side view of the fuel cell stack. It is a principal part disassembled perspective view of the said fuel cell stack. It is a partial cross section side view of the said fuel cell stack. It is a disassembled perspective view of the terminal plate and insulation plate which comprise the said fuel cell stack. It is a partial cross section side view of the fuel cell stack concerning the 2nd Embodiment of the present invention. It is a partial cross section side view of the fuel cell stack concerning the 3rd Embodiment of the present invention. 1 is a schematic configuration explanatory diagram of a fuel cell stack of Patent Document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 90, 100 ... Fuel cell stack 12 ... Fuel cell 14 ... Laminated body 16a, 16b ... Terminal plate 18a, 18b ... Insulation plate 20a, 20b ... End plate 30 ... Electrolyte membrane and electrode structure 32, 34 ... Metal separator 36a ... Oxidant gas inlet communication hole 36b ... Oxidant gas outlet communication hole 38a ... Cooling medium inlet communication hole 38b ... Cooling medium outlet communication hole 40a ... Fuel gas inlet communication hole 40b ... Fuel gas outlet communication hole 42 ... Fuel gas flow path 44 ... cooling medium flow path 46 ... oxidant gas flow path 52 ... solid polymer electrolyte membrane 54 ... anode side electrode 56 ... cathode side electrode 60a, 60b, 102 ... recesses 70, 70a to 70c, 92, 106 ... curved portion 72a, 72b, 78a, 78b, 80a, 80b ... piping manifold 104 ... loading member

Claims (3)

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 laminated in a horizontal direction, and the electrode is disposed between the electrolyte / electrode structure and one separator. A reaction gas flow path for supplying a reaction gas along the surface direction of the reaction gas, and a reaction that communicates with a supply-side end or a discharge-side end of the reaction gas flow path and penetrates the stacked body in the stacking direction. An internal manifold type fuel cell stack in which a gas communication hole is formed,
The reactive gas communication hole has one end in the stacking direction opened and the other end in the stacking direction closed.
The fuel cell stack according to claim 1, wherein an end member having a curved portion communicating with the reaction gas communication hole is disposed at least on a lower side at the other end in the stacking direction.   2. The fuel cell stack according to claim 1, wherein the end member is at least one of a terminal plate, an insulating plate, and an end plate stacked on the stacked body.   3. The fuel cell stack according to claim 1, wherein the curved portion is provided on a loading member disposed on the end member. 4.

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