JP2011204512A - Fuel cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell stack in which occurrence of liquid junction between power generation cells can be prevented as much as possible in a simple structure.SOLUTION: The fuel cell stack 10 has a plurality of power generation cells 12 laminated in a gravity direction on an electrode surface as a horizontal surface. A manifold member 60b communicating to an oxidant gas exhausting communication hole 28b is connected to an end plate 20b which is an lower end part in a lamination direction of the fuel cell stack 10, and a projection part 70 provided in projection inside the manifold member 60b is arranged at the lower end part of an exhaust piping 68a forming the oxidant gas exhausting communication hole 28b.

Description

  The present invention includes an electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of an electrolyte, and a separator, a reaction gas flow path for flowing a reaction gas in an electrode surface direction, and the reaction gas of the separator. The present invention relates to a fuel cell stack including a power generation cell in which a reaction gas supply communication hole and a reaction gas discharge communication hole that are circulated in a stacking direction are formed, and the plurality of power generation cells are stacked in a gravity direction with an electrode surface as a horizontal plane.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (an electrolyte / electrode structure) in which an anode electrode and a cathode electrode are disposed on both sides of an electrolyte membrane (electrolyte) made of a polymer ion exchange membrane, respectively. ) (MEA) is provided with a unit cell (power generation cell) sandwiched between separators.

  This type of fuel cell is usually used as a fuel cell stack in which a predetermined number (for example, several tens to several hundreds) of unit cells are stacked in order to obtain a desired power generation when used for in-vehicle use. Yes. In that case, the fuel cell stack generally includes a reaction gas flow channel for flowing a reaction gas along the electrode surface in the plane of the separator, and a reaction communicating with the reaction gas flow channel and penetrating in the stacking direction of the unit cells. A so-called internal manifold having a gas communication hole is employed.

  In this type of internal manifold type fuel cell stack, it is necessary to ensure insulation of the entire fuel cell system in order to prevent so-called liquid junction, in which current flows through a cooling medium and reaction product water. Therefore, for example, a fuel cell system disclosed in Patent Document 1 is known.

  As shown in FIG. 10, this fuel cell system includes a fuel cell 1, and the fuel cell 1 includes a set of fuel cell stacks 2 housed in a stack case 3. The fuel cell stack 2 is provided side by side so that the cell modules 2a and 2b are fastened and held between the end plates 4a and 4b. Connected to the end plate 4a are supply pipes 5a, 6a and 7a for humidified hydrogen gas, humidified air and coolant, and discharge pipes 5b, 6b and 7b, respectively. These supply pipes 5a to 7a and discharge pipes 5b to 7b are formed of an electrically insulating member.

JP-A-2005-332673

  However, in the above-mentioned Patent Document 1, for example, the discharge pipes 5b and 6b through which hydrogen gas and air are discharged are formed of an electrically insulating member, but condensate water is connected from the cell modules 2a and 2b. There is a risk of being discharged. For this reason, a liquid junction is caused between the stacked cell modules 2a and 2b. In particular, when a metal separator is used as a separator, a corrosion current tends to be generated on the surface of the metal separator due to a potential difference.

  For this reason, the metal ions eluted by the corrosion of the metal separator enter and the function of the electrolyte membrane is lowered, and the metal separator is thinned (perforated) by the corrosion and the gas blocking function is lowered. There is.

  The present invention solves this type of problem, and an object thereof is to provide a fuel cell stack capable of preventing liquid junctions between power generation cells as much as possible with a simple configuration.

  The present invention includes an electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of an electrolyte, and a separator, a reaction gas flow path for flowing a reaction gas in an electrode surface direction, and the reaction gas of the separator. The present invention relates to a fuel cell stack including a power generation cell in which a reaction gas supply communication hole and a reaction gas discharge communication hole that are circulated in a stacking direction are formed, and the plurality of power generation cells are stacked in a gravitational direction with an electrode surface as a horizontal plane. is there.

  A manifold member communicating with at least the reaction gas discharge communication hole is connected to a lower end portion in the stacking direction of the fuel cell stack, and at least a manifold member communicating with the reaction gas discharge communication hole is connected to the manifold member. A protruding portion is provided so as to protrude inside.

  Further, in this fuel cell stack, it is preferable that a tapered portion inclined downward is formed at the lower end of the protruding portion of the discharge pipe.

  Further, in this fuel cell stack, it is preferable that a protruding portion protruding outward is formed on the outer peripheral portion of the protruding portion of the discharge pipe.

  Furthermore, in this fuel cell stack, it is preferable that a step is formed at the lower end of the protruding portion of the discharge pipe.

  Further, in this fuel cell stack, it is preferable that a curved portion is formed at the lower end of the protruding portion of the discharge pipe.

  According to the present invention, at least the lower end portion of the discharge pipe that forms the reaction gas discharge communication hole is provided with a protruding portion that protrudes into the manifold member. For this reason, the dew condensation water that moves in the direction of gravity along the reactive gas discharge communication hole is discharged to the inside of the manifold member with the continuity (connection) cut off under the action of the protruding portion. Accordingly, it is possible to prevent the occurrence of a liquid junction between the power generation cells as much as possible with a simple configuration.

1 is a schematic perspective explanatory view of a fuel cell stack according to a first embodiment of the present invention. It is a disassembled perspective explanatory drawing of the power generation cell which comprises the said fuel cell stack. FIG. 3 is a cross-sectional view of the fuel cell stack taken along line III-III in FIG. 2. It is a schematic perspective view from the lower end part of the fuel cell stack. FIG. 5 is a cross-sectional view of the fuel cell stack taken along line VV in FIG. 4. FIG. 4 is a partial cross-sectional clear view of a fuel cell stack according to a second embodiment of the present invention. FIG. 6 is a partial sectional clear view of a fuel cell stack according to a third embodiment of the present invention. It is a partial cross-section clear view of the fuel cell stack which concerns on the 4th Embodiment of this invention. FIG. 9 is a partial sectional clear view of a fuel cell stack according to a fifth embodiment of the present invention. 2 is an explanatory diagram of a fuel cell system disclosed in Patent Document 1. FIG.

  As shown in FIG. 1, the fuel cell stack 10 according to the first embodiment of the present invention includes a plurality of power generation cells (unit cells) 12 stacked in the direction of gravity (the direction of arrow A) with the electrode surface as a horizontal plane. A laminated body 14 is provided. At one end (upper end) in the stacking direction (arrow A direction) of the stacked body 14, a terminal plate 16a, an insulating plate 18a, and an end plate 20a are disposed upward. A terminal plate 16b, an insulating plate 18b, and an end plate 20b are disposed downward at the other end (lower end) of the stacked body 14 in the stacking direction.

  Both ends of a plurality of connecting bars 21 are fixed to the end plates 20a and 20b, and a tightening load is applied between the end plates 20a and 20b in the stacking direction. A tightening load may be applied between the end plates 20a and 20b in the stacking direction via a tie rod (not shown), or a tightening load may be applied in the stacking direction via a box-shaped casing.

  As shown in FIGS. 2 and 3, each power generation cell 12 includes an electrolyte membrane / electrode structure (MEA) 22, and a first metal separator 24 and a second metal separator 26 that sandwich the electrolyte membrane / electrode structure 22. With.

  The first metal separator 24 and the second metal separator 26 are made of, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a vertically long metal plate having a surface treated for anticorrosion on the metal surface. The first and second metal separators 24 and 26 have a rectangular planar shape, and are formed into a concavo-convex shape by pressing a metal thin plate into a corrugated plate shape. Instead of the first metal separator 24 and the second metal separator 26, for example, a carbon separator (not shown) may be used.

  As shown in FIG. 2, an oxidant for supplying an oxidant gas, for example, an oxygen-containing gas, to one end edge of the power generation cell 12 in the arrow B direction (horizontal direction) in communication with each other in the arrow A direction. Gas supply communication hole (reaction gas supply communication hole) 28a, cooling medium supply communication hole 30a for supplying a cooling medium, and fuel gas discharge communication hole (reactive gas discharge for discharging a hydrogen-containing gas, for example) (Communication hole) 32b is provided.

  The other end edge of the power generation cell 12 in the direction of arrow B communicates with each other in the direction of arrow A, discharges a fuel gas supply communication hole (reaction gas supply communication hole) 32a for supplying fuel gas, and discharges the cooling medium. A cooling medium discharge communication hole 30b for the purpose and an oxidant gas discharge communication hole (reactive gas discharge communication hole) 28b for discharging the oxidant gas are provided.

  On the surface 24a of the first metal separator 24 on the electrolyte membrane / electrode structure 22 side, for example, an oxidant gas flow path 36 extending in the arrow B direction (electrode surface direction) is provided. The oxidant gas flow path 36 communicates with the oxidant gas supply communication hole 28a and the oxidant gas discharge communication hole 28b. A cooling medium flow path 38 is formed on the surface 24 b opposite to the surface 24 a of the first metal separator 24. The cooling medium flow path 38 communicates with the cooling medium supply communication hole 30a and the cooling medium discharge communication hole 30b.

  The surface 26a of the second metal separator 26 on the electrolyte membrane / electrode structure 22 side communicates with the fuel gas supply communication hole 32a and the fuel gas discharge communication hole 32b and extends in the direction of arrow B (electrode surface direction). A fuel gas flow path 40 is formed. The cooling medium flow communicating with the cooling medium supply communication hole 30a and the cooling medium discharge communication hole 30b is overlapped with the surface 24b of the first metal separator 24 on the surface 26b opposite to the surface 26a of the second metal separator 26. A path 38 is formed.

  In the first metal separator 24, the first seal member 42 is integrally injection-molded on the metal thin plate, and in the second metal separator 26, the second seal member 44 is integrally injection-molded on the metal thin plate.

  The first and second sealing members 42 and 44 are, for example, EPDM, NBR, fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene, acrylic rubber, or other sealing materials, cushion materials, Alternatively, a packing material is used.

  The first seal member 42 communicates the oxidant gas supply communication hole 28 a and the oxidant gas discharge communication hole 28 b to the oxidant gas flow path 36 on the surface 24 a side of the first metal separator 24. The first seal member 42 is integrally formed with an inlet side bridge portion 46a and an outlet side bridge portion 46b so as to be close to the oxidant gas supply communication hole 28a and the oxidant gas discharge communication hole 28b, respectively.

  The second seal member 44 communicates the fuel gas supply communication hole 32 a and the fuel gas discharge communication hole 32 b with the fuel gas flow path 40 on the surface 26 a side of the second metal separator 26. In the second seal member 44, an inlet-side bridge portion 48a and an outlet-side bridge portion 48b are integrally formed adjacent to the fuel gas supply communication hole 32a and the fuel gas discharge communication hole 32b, respectively.

  The second seal member 44 communicates the cooling medium supply communication hole 30 a, the cooling medium discharge communication hole 30 b, and the cooling medium flow path 38 on the surface 26 b side of the second metal separator 26. In the second seal member 44, an inlet side bridge portion 50a and an outlet side bridge portion 50b are integrally formed adjacent to the cooling medium supply communication hole 30a and the cooling medium discharge communication hole 30b, respectively.

  As shown in FIGS. 2 and 3, the electrolyte membrane / electrode structure 22 includes, for example, a solid polymer electrolyte membrane (electrolyte) 52 in which a perfluorosulfonic acid thin film is impregnated with water, and the solid polymer electrolyte membrane. A cathode-side electrode 54 and an anode-side electrode 56 sandwiching 52.

  The cathode side electrode 54 and the anode side electrode 56 are formed by uniformly applying a gas diffusion layer made of carbon paper or the like and porous carbon particles carrying a platinum alloy on the surface thereof to the surface of the gas diffusion layer. An electrode catalyst layer. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 52.

  As shown in FIG. 4, an oxidant gas supply communication hole 28a, a cooling medium supply communication hole 30a, a fuel gas discharge communication hole 32b, and a fuel gas supply communication are provided on the end plate 20b, which is the lower end of the fuel cell stack 10 in the stacking direction. Manifold members 60a, 62a, 64b, 64a, 62b, and 60b are provided in communication with the hole 32a, the cooling medium discharge communication hole 30b, and the oxidant gas discharge communication hole 28b, respectively.

  The end plate 20b includes supply pipes 66a, 66b, and 66c that form an oxidant gas supply communication hole 28a, a cooling medium supply communication hole 30a, and a fuel gas supply communication hole 32a, an oxidant gas discharge communication hole 28b, and a cooling medium discharge. Discharge pipes 68a, 68b and 68c forming the communication hole 30b and the fuel gas discharge communication hole 32b are connected.

  As shown in FIG. 5, the discharge pipe 68a is inserted into the end plate 20b and penetrates in the direction of gravity to form an oxidant gas discharge communication hole 28b. At the lower end of the discharge pipe 68a, a protruding portion 70 is provided that protrudes by a length h inside the manifold member 60b. The other discharge pipes 68b and 68c and the supply pipes 66a to 66c are configured in the same manner as the discharge pipe 68a described above, and a detailed description thereof is omitted.

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

  First, as shown in FIG. 4, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas supply communication hole 28a via the manifold member 60a of the end plate 20b, and the fuel is supplied via the manifold member 64a. A fuel gas such as a hydrogen-containing gas is supplied to the gas supply communication hole 32a. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium supply communication hole 30a through the manifold member 62a.

  Therefore, the oxidant gas is introduced into the oxidant gas flow path 36 provided in the first metal separator 24 from the oxidant gas supply communication hole 28a as shown in FIG. As a result, the oxidant gas is supplied to the cathode side electrode 54 constituting the electrolyte membrane / electrode structure 22 while moving in the direction of the arrow B in the oxidant gas flow path 36.

  On the other hand, the fuel gas is introduced into the fuel gas flow path 40 provided in the second metal separator 26 from the fuel gas supply communication hole 32a. The fuel gas introduced into the fuel gas flow path 40 is supplied to the anode side electrode 56 constituting the electrolyte membrane / electrode structure 22 while moving in the arrow B direction.

  Therefore, in the electrolyte membrane / electrode structure 22, the oxidant gas supplied to the cathode side electrode 54 and the fuel gas supplied to the anode side electrode 56 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 54 is discharged to the oxidant gas discharge communication hole 28b. On the other hand, the used fuel gas consumed by being supplied to the anode electrode 56 is discharged to the fuel gas discharge communication hole 32b. The cooling medium flows in the direction of arrow B after being introduced into the cooling medium flow path 38 from the cooling medium supply communication hole 30a. The cooling medium is discharged to the cooling medium discharge communication hole 30b after the electrolyte membrane / electrode structure 22 is cooled.

  By the way, in the oxidant gas flow path 36, the oxidant gas sent from the oxidant gas supply communication hole 28a is used by the power generation reaction and water is generated. The generated water is discharged to the oxidant gas discharge communication hole 28b along with the used oxidant gas.

  In this case, in the first embodiment, for example, as shown in FIG. 5, the lower end portion of the discharge pipe 68a forming the oxidant gas discharge communication hole 28b protrudes by a length h inside the manifold member 60b. A protruding portion 70 is provided. For this reason, the dew condensation water W that moves in the direction of gravity along the oxidant gas discharge communication hole 28b with the used oxidant gas is cut off from continuity (connection) under the action of the protruding portion 70, and thus the manifold. It is discharged into the member 60b.

  Therefore, it is possible to prevent the occurrence of a liquid junction between the power generation cells 12 with a simple configuration as much as possible. Thereby, especially the 1st metal separator 24 and the 2nd metal separator 26 do not generate | occur | produce the corrosion current by an electrical potential difference, and can prevent the fall of the gas interruption | blocking function by thickness reduction well. For this reason, the effect that it becomes possible to use each electric power generation cell 12 efficiently and satisfactorily for a long period of time is acquired.

  Further, as shown in FIG. 4, a protruding portion 70 is provided at the lower end portion of the discharge pipe 68c that forms the fuel gas discharge communication hole 32b. Therefore, the dew condensation water W that moves in the direction of gravity along the fuel gas discharge communication hole 32b is blocked by the protruding portion 70, so that the continuity is satisfactorily blocked and a liquid junction is prevented.

  The end plate 20b is provided with supply pipes 66a and 66c that form the oxidant gas supply communication hole 28a and the fuel gas supply communication hole 32a. For this reason, the dew condensation water W that moves in the gravity direction along the oxidant gas supply communication hole 28a and the dew condensation water W that moves in the gravity direction along the fuel gas supply communication hole 32a have good continuity, respectively. A liquid junction can be prevented.

  FIG. 6 is a partial cross-sectional explanatory view of a fuel cell stack 80 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. Here, in the second and subsequent embodiments, only the oxidant gas discharge communication hole 28b will be described, but it goes without saying that other communication holes are similarly configured.

  In the fuel cell stack 80, the end plate 20b that is the lower end portion in the stacking direction is provided with a discharge pipe 82 that forms the oxidant gas discharge communication hole 28b. The discharge pipe 82 is provided with a protruding portion 84 that protrudes from the manifold member 60b by a length h, and a tapered portion that tapers downward at the lower end of the protruding portion 84. 86 is formed. Therefore, the dew condensation water W is discharged | emitted favorably and a liquid junction can be prevented.

  FIG. 7 is a partial cross-sectional explanatory view of a fuel cell stack 90 according to the third embodiment of the present invention.

  The fuel cell stack 90 includes a discharge pipe 92 that is attached to the end plate 20b and forms the oxidant gas discharge communication hole 28b. The lower end portion of the discharge pipe 92 is provided with a protruding portion 94 that protrudes into the manifold member 60b. A protruding portion 96 that protrudes to the outside is formed on the outer peripheral portion of the protruding portion 94. Thereby, the liquid connection of the outer periphery of the protrusion part 94 can be prevented.

  FIG. 8 is a partial cross-sectional explanatory view of a fuel cell stack 100 according to the fourth embodiment of the present invention.

  The fuel cell stack 100 includes a discharge pipe 102 that is attached to the end plate 20b and forms the oxidant gas discharge communication hole 28b. At the lower end portion of the discharge pipe 102, a protruding portion 104 is formed so as to protrude inside the manifold member 60 b, and a step portion 106 is formed at the lower end of the protruding portion 104. Therefore, the continuous connection of the liquid is prevented by the step 106 at the lower end of the protruding portion 104.

  FIG. 9 is a partial cross-sectional explanatory view of a fuel cell stack 110 according to the fifth embodiment of the present invention.

  The fuel cell stack 110 includes a discharge pipe 112 that is attached to the end plate 20b and forms the oxidant gas discharge communication hole 28b. A protruding portion 114 is provided at the lower end portion of the discharge pipe 112 so as to protrude into the manifold member 60 b, and a curved shape portion 116 is formed at the lower end of the protruding portion 114.

  In the second to fifth embodiments configured as described above, the shape of the protruding portions 84, 94, 104, and 114 is changed variously to move by its own weight along the oxidant gas discharge communication hole 28b. In addition to being able to more reliably block the continuity of the condensed water to be produced, the same effects as in the first embodiment can be obtained.

DESCRIPTION OF SYMBOLS 10, 80, 90, 100, 110 ... Fuel cell stack 12 ... Power generation cell 14 ... Laminated body 16a, 16b ... Terminal plate 18a, 18b ... Insulating plate 20a, 20b ... End plate 22 ... Electrolyte membrane and electrode structure 24, 26 ... Metal separator 28a ... Oxidant gas supply communication hole 28b ... Oxidant gas discharge communication hole 30a ... Cooling medium supply communication hole 30b ... Cooling medium discharge communication hole 32a ... Fuel gas supply communication hole 32b ... Fuel gas discharge communication hole 36 ... Oxidation Agent gas flow path 38 ... Cooling medium flow path 40 ... Fuel gas flow path 42, 44 ... Seal member 52 ... Solid polymer electrolyte membrane 54 ... Cathode side electrode 56 ... Anode side electrodes 66a, 66b, 66c ... Supply piping 68a, 68b , 68c, 82, 92, 102, 112 ... discharge piping 70, 84, 94, 104, 114 ... protruding portion 86 ... Tapered shape portion 96 ... Projection portion 106 ... Step portion 116 ... Curved shape portion

Claims (5)

An electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of the electrolyte and a separator are stacked, a reaction gas flow path for flowing a reaction gas in the electrode surface direction, and a flow of the reaction gas in the stacking direction of the separator A fuel cell stack including a power generation cell in which a reaction gas supply communication hole and a reaction gas discharge communication hole are formed, wherein the plurality of power generation cells are stacked in a gravitational direction with an electrode surface as a horizontal plane,
A manifold member connected to at least the reaction gas discharge communication hole is connected to the lower end portion in the stacking direction of the fuel cell stack,
A fuel cell stack, characterized in that at least a lower end portion of a discharge pipe that forms the reaction gas discharge communication hole is provided with a protruding portion that protrudes into the manifold member.   2. The fuel cell stack according to claim 1, wherein a tapered portion inclined downward is formed at a lower end of the protruding portion of the discharge pipe. 3.   2. The fuel cell stack according to claim 1, wherein a protrusion protruding outward is formed on an outer peripheral portion of the protruding portion of the discharge pipe.   2. The fuel cell stack according to claim 1, wherein a step portion is formed at a lower end of the protruding portion of the discharge pipe.   2. The fuel cell stack according to claim 1, wherein a curved portion is formed at a lower end of the protruding portion of the discharge pipe.

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