JP2010186591A - Fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out efficient power generation certainly by maintaining constant the temperature ambient during power generation between mutually adjoining fuel cells, with a simple and economical structure. <P>SOLUTION: The power generation unit 12 to constitute a fuel cell 10 is provided with an anode-side separator 14, a first electrolyte membrane-electrode structure 16a, an intermediate separator 18, a second electrolyte membrane-electrode structure 16b, and a cathode-side separator 20. The width dimension W1 of a flat part 56b where the cathode-side separator 20 is in contact with the cathode-side electrode 26 of the second electrolyte membrane-electrode structure 16b is established wider than the width dimension W2 of the flat portion 36b where the anode-side separator 14 is in contact with the anode-side electrode 24 of the first electrolyte membrane-electrode structure 16a. The height H1 in a lamination direction of the cathode-side separator 20 is established higher than the height H2 in a lamination direction of the anode-side separator 14. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell stack including a fuel cell in which an anode-side separator and a cathode-side separator are stacked with an electrolyte / electrode structure interposed therebetween, and a cooling medium flow path formed between the fuel cells stacked on each other.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (MEA) in which an anode side electrode and a cathode side electrode are disposed on both sides of an electrolyte membrane made of a polymer ion exchange membrane is provided by a pair of separators. The unit cell is sandwiched. This type of fuel cell is normally used as a fuel cell stack by stacking a predetermined number of unit cells.

  In the above fuel cell, in the plane of the separator, a fuel gas channel for flowing fuel gas facing the anode side electrode, and an oxidant gas channel for flowing oxidant gas facing the cathode side electrode And are provided. Further, between the separators, a cooling medium flow path for flowing the cooling medium is provided along the surface direction of the separator.

  By the way, the fuel cell stack may adopt a so-called thinning cooling structure in which a cooling medium flow path is formed between a predetermined number of unit cells. In a fuel cell having this kind of thinning cooling structure, for example, as disclosed in Patent Document 1 shown in FIG. 6, a separator 1, a cell 2, a separator 3, a cell 2 and a separator 4 are laminated.

  In the cell 2, the fuel electrode 2b and the air electrode 2c are disposed on both surfaces of the solid polymer electrolyte membrane 2a. A fuel gas passage 5 a is formed between the separator 1 and one cell 2, and an oxidant gas passage 6 a is formed between the separator 3 and the one cell 2. A fuel gas passage 5 b is formed between the separator 3 and the other cell 2, and an oxidant gas passage 6 b is formed between the separator 4 and the other cell 2. A cooling water passage 7 is formed between the separators 1 and 4 adjacent to each other.

JP 2002-289223 A

  In the above fuel cell, in particular, the oxidant gas passage 6 b in contact with the cooling water passage 7 is at a higher temperature than the fuel gas passage 5 a in contact with the cooling water passage 7. For this reason, the temperature environment during power generation differs between the adjacent cells 2 across the cooling water passage 7, the amount of condensed water generated during the power generation is not uniformed, and stable power generation is not performed. There is.

  The present invention solves this type of problem, and with a simple and economical configuration, maintains a constant temperature environment during power generation between adjacent fuel cells and reliably performs efficient power generation. 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 an anode side electrode and a cathode side electrode are disposed on both sides of an electrolyte, an anode side separator that forms a fuel gas flow path between the anode side electrode, and the cathode side A fuel cell in which a cathode-side separator that forms an oxidant gas flow path between the electrodes is stacked; the anode-side separator that constitutes one fuel cell; and the cathode-side separator that constitutes the other fuel cell; The present invention relates to a fuel cell stack in which a cooling medium flow path is formed between the two.

  In this fuel cell stack, the width of the flat portion where the cathode separator forming the cooling medium flow path contacts the electrolyte / electrode structure is such that the anode side separator forming the cooling medium flow path is the electrolyte / electrode structure. The height of the cathode separator in the stacking direction is set to be higher than the height of the anode separator in the stacking direction.

  The fuel cell is laminated in the order of an anode side separator, a first electrolyte / electrode structure, an intermediate separator, a second electrolyte / electrode structure, and a cathode side separator, and the intermediate separator includes the first separator An oxidant gas flow path is formed between the cathode side electrode of the electrolyte / electrode structure and a fuel gas flow path is formed between the anode side electrode of the second electrolyte / electrode structure. Is preferred.

  According to the present invention, the width dimension of the flat portion where the cathode separator contacts the electrolyte / electrode structure is set wider than the width dimension of the flat portion where the anode separator contacts the electrolyte / electrode structure. Yes. For this reason, the amount of heat drawn by the electrolyte / electrode structure with which the flat portion of the cathode separator contacts is increased, and the temperature of the oxidant gas flow path is lowered. Furthermore, since the contact width dimension of the flat part of a cathode side separator is set large, contact resistance is reduced and the emitted-heat amount is suppressed.

  As a result, the oxidant gas flow channel and the fuel gas flow channel adjacent to the cooling medium flow channel can maintain a constant temperature environment during power generation, reducing the temperature difference between the fuel cells and improving efficiency. Power generation can be performed reliably.

  Moreover, the height of the cathode separator in the stacking direction is set higher than the height of the anode separator in the stacking direction. Therefore, the oxidant gas flow path having a narrow flow path width can secure a desired flow path cross-sectional area by setting the dimension in the height direction to be large, and the oxidant gas distribution is maintained well. The

It is a principal part disassembled perspective explanatory drawing of the electric power generation unit which comprises the fuel cell stack which concerns on embodiment of this invention. FIG. 2 is a sectional view of the fuel cell stack taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional explanatory view of the fuel cell stack. It is front explanatory drawing of the anode side separator which comprises the said electric power generation unit. It is front explanatory drawing of the intermediate separator which comprises the said electric power generation unit. It is explanatory drawing of the fuel cell which has the conventional thinning cooling structure.

  FIG. 1 is an exploded perspective view of a main part of a power generation unit 12 constituting a fuel cell stack 10 according to an embodiment of the present invention.

  As shown in FIGS. 2 and 3, the fuel cell stack 10 is configured by stacking a plurality of power generation units 12 along the horizontal direction (arrow A direction). The power generation unit 12 includes an anode separator 14, a first electrolyte membrane / electrode structure (electrolyte / electrode structure) (MEA) 16 a, an intermediate separator 18, a second electrolyte membrane / electrode structure 16 b, and a cathode separator 20. .

  The anode-side separator 14, the intermediate separator 18, and the cathode-side separator 20 are made of, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a metal plate whose surface is subjected to anticorrosion. The anode side separator 14, the intermediate separator 18, and the cathode side separator 20 have a concavo-convex shape by pressing a metal thin plate into a wave shape. In addition, you may comprise the anode side separator 14, the intermediate | middle separator 18, and the cathode side separator 20 with a carbon separator, for example.

  As shown in FIGS. 1 and 2, the first electrolyte membrane / electrode structure 16a is set to have a smaller surface area than the second electrolyte membrane / electrode structure 16b. The first and second electrolyte membrane / electrode structures 16a and 16b include, for example, a solid polymer electrolyte membrane 22 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode side sandwiching the solid polymer electrolyte membrane 22 The electrode 24 and the cathode side electrode 26 are provided. The anode side electrode 24 constitutes a so-called stepped MEA having a smaller surface area than the cathode side electrode 26.

  The anode side electrode 24 and the cathode side electrode 26 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. And an electrode catalyst layer (not shown) formed. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 22.

  As shown in FIG. 1, the upper end edge (in the direction of arrow C) in the long side direction of the power generation unit 12 communicates with each other in the direction of arrow A to oxidize for supplying an oxidant gas, eg, an oxygen-containing gas An agent gas inlet communication hole 30a, a fuel gas inlet communication hole 32a for supplying a fuel gas, for example, a hydrogen-containing gas, and a cooling medium inlet communication hole 34a for supplying a cooling medium are provided.

  The lower end edge of the power generation unit 12 in the long side direction (arrow C direction) communicates with each other in the direction of arrow A, the fuel gas outlet communication hole 32b for discharging fuel gas, and for discharging the oxidant gas An oxidizing gas outlet communication hole 30b and a cooling medium outlet communication hole 34b for discharging the cooling medium are provided.

  On the surface 14a of the anode separator 14 facing the first electrolyte membrane / electrode structure 16a, for example, a first fuel gas passage 36 extending in the direction of arrow C is provided. The first fuel gas channel 36 is provided with channel grooves 36a and flat portions 36b alternately in the direction of arrow B (see FIG. 3). The first fuel gas flow path 36 communicates with the fuel gas inlet communication hole 32a and the fuel gas outlet communication hole 32b via the first inlet side communication path portion 38a and the first outlet side communication path portion 38b (see FIG. 1). ).

  As shown in FIGS. 1 and 4, the first inlet side communication passage portion 38a includes a plurality of connecting passages 40a provided on the surface 14b opposite to the surface 14a and connected to the fuel gas inlet communication hole 32a, and the anode side. A plurality of through holes 42 a that penetrate the separator 14 in the stacking direction and communicate with the connecting passage 40 a and the first fuel gas passage 36 are provided. Similarly, the first outlet side communication path portion 38b is provided on the surface 14b and communicates with the fuel gas outlet communication hole 32b and the anode side separator 14 in the stacking direction, and the connection path 40b. And a plurality of through holes 42 b communicating with the first fuel gas channel 36.

  A part of the cooling medium flow path 44 that connects the cooling medium inlet communication hole 34 a and the cooling medium outlet communication hole 34 b is formed on the surface 14 b of the anode side separator 14.

  As shown in FIG. 1, the surface 18a of the intermediate separator 18 facing the first electrolyte membrane / electrode structure 16a has a first oxidant communicating with an oxidant gas inlet communication hole 30a and an oxidant gas outlet communication hole 30b. A gas flow path 46 is formed. As shown in FIGS. 3 and 5, the first oxidizing gas channel 46 has a plurality of channel grooves 46 a and flat portions 46 b that extend in the direction of arrow C alternately.

  On the surface 18b of the intermediate separator 18 facing the second electrolyte membrane / electrode structure 16b, for example, a second fuel gas channel 48 having a plurality of grooves extending in the direction of arrow C is provided. The second fuel gas channel 48 is provided with channel grooves 48a and flat portions 48b alternately in the arrow B direction. The second fuel gas flow path 48 communicates with the fuel gas inlet communication hole 32a and the fuel gas outlet communication hole 32b via the second inlet side communication path portion 50a and the second outlet side communication path portion 50b.

  As shown in FIGS. 1 and 5, the second inlet side communication passage portion 50a penetrates the intermediate separator 18 in the stacking direction and a plurality of connection passages 52a provided on the surface 18a and communicating with the fuel gas inlet communication hole 32a. And a plurality of through holes 54 a communicating with the connecting passage 52 a and the second fuel gas passage 48. Similarly, the second outlet side communication passage portion 50b includes a plurality of connection paths 52b provided on the surface 18a and communicating with the fuel gas outlet communication holes 32b, and the connection paths 52b passing through the intermediate separator 18 in the stacking direction. And a plurality of through holes 54 b communicating with the second fuel gas channel 48.

  As shown in FIG. 1, the surface 20a of the cathode separator 20 facing the second electrolyte membrane / electrode structure 16b is connected to the oxidant gas inlet communication hole 30a and the oxidant gas outlet communication hole 30b. An agent gas channel 56 is formed. The second oxidizing gas channel 56 has a plurality of channel grooves 56a and flat portions 56b extending in the direction of arrow C alternately (see FIG. 3). A part of the cooling medium flow path 44 is formed on the surface 20 b of the cathode separator 20.

  As shown in FIGS. 1, 2, and 4, the first seal member 60 is integrally formed on the surfaces 14 a and 14 b of the anode-side separator 14 around the outer peripheral edge of the anode-side separator 14. As shown in FIGS. 1, 2, and 5, the surfaces 18 a and 18 b of the intermediate separator 18 are integrally formed with a second seal member 62 around the outer peripheral edge of the intermediate separator 18, and the cathode A third seal member 64 is integrally formed on the surfaces 20a and 20b of the side separator 20 around the outer peripheral edge of the cathode side separator 20 (see FIGS. 1 and 2).

  Since the power generation units 12 are stacked on each other, the anode side separator 14 constituting one power generation unit 12 and the cathode side separator 20 constituting the other power generation unit 12 extend in the direction of arrow C. A cooling medium flow path 44 is formed (see FIGS. 1 and 3). The cooling medium flow path 44 has flow path grooves 44a and flat portions 44b alternately.

  As shown in FIG. 3, the width dimension W1 of the flat portion 56b where the cathode separator 20 contacts the cathode electrode 26 of the second electrolyte membrane / electrode structure 16b is such that the anode separator 14 has the first electrolyte membrane / electrode structure. The width is set wider than the width dimension W2 of the flat portion 36b (and the flat portion 46b) contacting the anode side electrode 24 of the body 16a (W1> W2).

  The height H1 of the cathode-side separator 20 in the stacking direction (arrow A direction) is set to be higher than the height H2 of the anode-side separator 14 in the stacking direction (H1> H2). That is, the first oxidant gas channel 46 and the second oxidant gas channel 56 have the same opening channel area.

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

  First, as shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 30a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 32a. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 34a.

  Therefore, the oxidant gas is introduced from the oxidant gas inlet communication hole 30a into the first oxidant gas flow path 46 of the intermediate separator 18 and the second oxidant gas flow path 56 of the cathode side separator 20. The oxidant gas moves in the direction of arrow C (the direction of gravity) along the first oxidant gas flow path 46 and is supplied to the cathode side electrode 26 of the first electrolyte membrane / electrode structure 16a. It moves in the direction of arrow C along the oxidant gas flow path 56 and is supplied to the cathode electrode 26 of the second electrolyte membrane / electrode structure 16b.

  On the other hand, as shown in FIGS. 2 and 4, the fuel gas is supplied from the fuel gas inlet communication hole 32a to the connecting passage 40a constituting the first inlet side communication passage portion 38a of the anode side separator 14, and passes through the through hole 42a. It moves to the surface 14a side. For this reason, the fuel gas moves in the direction of gravity (arrow C direction) along the first fuel gas flow path 36 communicating with the through hole 42a, and is supplied to the anode side electrode 24 of the first electrolyte membrane / electrode structure 16a. Is done.

  Further, as shown in FIGS. 2 and 5, the fuel gas is supplied from the fuel gas inlet communication hole 32a to the connecting passage 52a constituting the second inlet side communication passage portion 50a of the intermediate separator 18, and passes through the through hole 54a. And move to the surface 18b side. Therefore, the fuel gas moves in the gravity direction (arrow C direction) along the second fuel gas flow path 48 communicating with the through hole 54a, and is supplied to the anode side electrode 24 of the second electrolyte membrane / electrode structure 16b. The

  Thus, in the first and second electrolyte membrane / electrode structures 16a and 16b, the oxidant gas supplied to the cathode side electrode 26 and the fuel gas supplied to the anode side electrode 24 are within the electrode catalyst layer. It is consumed by electrochemical reaction to generate electricity.

  Next, the oxidant gas consumed by being supplied to the cathode-side electrodes 26 of the first and second electrolyte membrane / electrode structures 16a and 16b is discharged in the direction of arrow A along the oxidant gas outlet communication hole 30b. The

  As shown in FIG. 4, the fuel gas consumed by being supplied to the anode side electrode 24 of the first electrolyte membrane / electrode structure 16a passes through the through-hole 42b constituting the first outlet side communication passage portion 38b and is then anode. It is led out to the surface 14 b side of the side separator 14. The fuel gas led out to the surface 14b side is discharged to the fuel gas outlet communication hole 32b through the connection path 40b.

  Further, as shown in FIG. 5, the fuel gas consumed by being supplied to the anode side electrode 24 of the second electrolyte membrane / electrode structure 16b passes through the through hole 54b constituting the second outlet side communication passage portion 50b. The intermediate separator 18 is led out to the surface 18a side. The fuel gas led out to the surface 18a side is discharged to the fuel gas outlet communication hole 32b through the connection path 52b.

  On the other hand, the cooling medium supplied to the cooling medium inlet communication hole 34 a is the cooling formed between the anode side separator 14 constituting one power generation unit 12 and the cathode side separator 20 constituting the other power generation unit 12. After being introduced into the medium flow path 44, it flows in the direction of arrow C. The cooling medium cools the first and second electrolyte membrane / electrode structures 16a and 16b, and then is discharged into the cooling medium outlet communication hole 34b.

  In this case, during power generation of the fuel cell stack 10, the second oxidant gas flow channel 56 adjacent to the cooling medium flow channel 44 has a higher temperature than the first fuel gas flow channel 36 adjacent to the cooling medium flow channel 44. Easy to be. For this reason, there is a possibility that dew condensation water is generated in the first fuel gas flow path 36 due to the heat absorption of the first electrolyte membrane / electrode structure 16a.

  Therefore, in this embodiment, as shown in FIG. 3, the width dimension W1 of the flat portion 56b where the cathode separator 20 contacts the cathode electrode 26 of the second electrolyte membrane / electrode structure 16b is set so that the anode separator 14 The width is set wider than the width dimension W2 of the flat portion 36b in contact with the anode side electrode 24 of the first electrolyte membrane / electrode structure 16a.

  Accordingly, the amount of heat drawn by the second electrolyte membrane / electrode structure 16b with which the flat portion 56b of the cathode-side separator 20 comes into contact increases, and the temperature of the second oxidant gas flow path 56 decreases. Moreover, since the contact width dimension of the flat portion 56b of the cathode side separator 20 is set large, the contact resistance is reduced and the amount of heat generated is suppressed.

  As a result, the second oxidant gas flow channel 56 and the first fuel gas flow channel 36 adjacent to the cooling medium flow channel 44 can maintain a constant temperature environment during power generation. The temperature difference is reduced, so that stable and efficient power generation can be reliably performed.

  Further, the height H1 of the cathode side separator 20 in the stacking direction is set to be higher than the height H2 of the anode side separator 14 in the stacking direction. Therefore, the second oxidant gas channel 56 having a narrow channel width can ensure a channel cross-sectional area equivalent to that of the first oxidant gas channel 46 by setting the dimension in the height direction large. . For this reason, the fuel cell stack 10 as a whole has an advantage that the oxidant gas distribution is maintained well.

  In the present embodiment, a so-called thinning cooling structure is employed in which the anode separator 14, the first electrolyte membrane / electrode structure 16a, the intermediate separator 18, the second electrolyte membrane / electrode structure 16b, and the cathode separator 20 are provided. However, the present invention is not limited to this. For example, a fuel cell in which an anode separator, an electrolyte membrane / electrode structure, and a cathode separator are stacked may be used.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell stack 12 ... Electric power generation unit 14, 18, 20 ... Separator 16a, 16b ... Electrolyte membrane electrode structure 22 ... Solid polymer electrolyte membrane 24 ... Anode side electrode 26 ... Cathode side electrode 30a ... Oxidant gas inlet communication Hole 30b ... Oxidant gas outlet communication hole 32a ... Fuel gas inlet communication hole 32b ... Fuel gas outlet communication hole 34a ... Cooling medium inlet communication hole 34b ... Cooling medium outlet communication hole 36, 48 ... Fuel gas flow paths 36a, 44a, 46a , 48a, 56a ... flow channel 36b, 44b, 46b, 48b, 56b ... flat portions 42a, 42b, 54a, 54b ... through hole 44 ... cooling medium flow channel 46, 56 ... oxidant gas flow channel

Claims (2)

Between the electrolyte-electrode structure in which the anode-side electrode and the cathode-side electrode are disposed on both sides of the electrolyte, the anode-side separator that forms a fuel gas flow path between the anode-side electrode, and the cathode-side electrode And a cathode side separator that forms an oxidant gas flow path, and is cooled between the anode side separator that constitutes one fuel cell and the cathode side separator that constitutes the other fuel cell. A fuel cell stack in which a medium flow path is formed,
The width dimension of the flat portion where the cathode separator forming the cooling medium flow path contacts the electrolyte / electrode structure is such that the anode side separator forming the cooling medium flow path contacts the electrolyte / electrode structure. It is set wider than the width dimension of the flat part to be
The fuel cell stack, wherein a height of the cathode separator in the stacking direction is set higher than a height of the anode separator in the stacking direction. 2. The fuel cell stack according to claim 1, wherein the fuel cell is laminated in the order of the anode separator, the first electrolyte / electrode structure, the intermediate separator, the second electrolyte / electrode structure, and the cathode separator. With
The intermediate separator forms an oxidant gas flow path between the intermediate electrode and the cathode electrode of the first electrolyte / electrode structure, and between the intermediate electrode and the anode electrode of the second electrolyte / electrode structure. A fuel cell stack, wherein a fuel gas flow path is formed.

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