JP2005100753A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply a reactant gas smoothly and uniformly along the surface of a separator with a simple structure, and to improve generating efficiency in the generating surface. <P>SOLUTION: The fuel cell 10 comprises a first and a second metal separators 14, 16 of rectangular shape interposing an electrolyte membrane/electrode structure 12 in between. A fuel gas passage 38 is formed between a protrusion part 36a and the first metal separator 14, and an oxidizer gas passage 42 is formed between a protrusion part 40a and the second metal separator 16. The fuel gas passage 38 is constructed of mutually facing first and second passages 38a, 38b of nearly U-shapes. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides a fuel cell comprising an electrolyte / electrode structure in which an anode side electrode and a cathode side electrode are provided on both sides of an electrolyte, and rectangular first and second separators sandwiching the electrolyte / electrode structure. About.

  For example, a polymer electrolyte fuel cell employs an electrolyte membrane (electrolyte) made of a polymer ion exchange membrane (cation exchange membrane). By sandwiching an electrolyte membrane / electrode structure having an anode-side electrode and a cathode-side electrode in which a noble metal-based electrode catalyst layer is bonded to a substrate mainly composed of carbon, on both sides of the electrolyte membrane, by a separator A fuel cell is configured.

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

  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 coolant flow path for allowing a coolant to flow as needed is provided along the surface direction of the separator. The fuel gas flow path, the oxidant gas flow path, and the cooling medium flow path generally move along the plane of the separator from the flow path inlet penetrating in the stacking direction of the separator toward the flow path outlet. It is configured.

  For example, the fuel cell separator disclosed in Patent Document 1 includes a separator plate 1 as shown in FIG. The separator plate 1 is made of a metal material that can be easily embossed or dimpled. A large number of protrusions 2 and 3 are formed on both the front and back surfaces at intervals of several mm by embossing or dimple processing.

  For example, a fuel gas inlet 4 a and a fuel gas outlet 4 b are provided at both side edges of the separator plate 1, and an oxidant gas inlet 5 a and an oxidant gas outlet are provided at both upper and lower edges of the separator plate 1. 5b is provided.

  The protrusion 2 protrudes toward the one surface 1a side of the separator plate 1, and a fuel gas passage 6 communicating with the fuel gas inlet 4a and the fuel gas outlet 4b is formed between the protrusions 2. The protrusion 3 protrudes toward the other surface 1b of the separator plate 1, and an oxidant gas passage 7 communicating with the oxidant gas inlet 5a and the oxidant gas outlet 5b is formed between the protrusions 3. Yes.

  In such a configuration, for example, when the fuel gas supplied to the fuel gas inlet 4 a is supplied to one surface 1 a of the separator plate 1, the fuel gas passage 6 formed continuously between the protrusions 2. In addition to being supplied to an electrode (not shown), unused fuel gas is discharged to the fuel gas outlet 4b.

  On the other hand, the oxidant gas supplied to the oxidant gas inlet 5a is supplied to an electrode (not shown) through an oxidant gas flow path 7 formed continuously between the protrusions 3 on the other surface 1b of the separator plate 1. At the same time, unused oxidant gas is discharged to the oxidant gas outlet 5b.

JP-A-8-222237 (paragraphs [0015] and [0016], FIG. 3)

  However, when the separator plate 1 is used in an upright position with the oxidant gas outlet 5b down, the fuel gas is supplied close to the fuel gas outlet 4b, particularly on the upper side in one surface 1a. A difficult region S is generated. This is because the flow rate of the fuel gas is considerably smaller than the flow rate of the oxidant gas. As a result, there is a problem that fuel gas is not sufficiently supplied to the corners of the electrode surface, causing power generation failure and nonuniform power generation in the electrode surface.

  In addition, in the region S, the flow rate of the fuel gas is significantly reduced, so that the condensed water tends to stay. For this reason, in this area | region S, there exists a problem that it becomes difficult to generate electric power further.

  The present invention solves this type of problem, and with a simple configuration, the reaction gas can be supplied smoothly and uniformly along the surface of the separator, and the power generation efficiency in the power generation surface can be improved. An object is to provide a possible fuel cell.

  The fuel cell of the present invention comprises an electrolyte / electrode structure in which an anode side electrode and a cathode side electrode are provided on both sides of an electrolyte, and first and second separators sandwiching the electrolyte / electrode structure, Between the anode side electrode and the first separator, a fuel gas flow path for supplying fuel gas is formed along the electrode surface, and between the cathode side electrode and the second separator, an electrode An oxidant gas flow path for supplying an oxidant gas along the surface is formed.

  The fuel gas flow path constitutes at least two substantially U-shaped flow paths extending along the plane of the first separator, while the oxidant gas flow path extends along the plane of the second separator. And constitutes a substantially straight flow path extending.

  In addition, the first separator is configured in a rectangular shape, and a fuel gas inlet and a fuel gas outlet are formed on the first side and the second side facing each other. It is preferable that two substantially U-shaped flow paths facing each other are provided in the plane.

  Further, the second separator is formed in a rectangular shape, and an oxidant gas inlet is formed on the third side intersecting the first and second sides, and the second separator is opposed to the third side. 4 is formed with an oxidant gas outlet, and the oxidant gas flow path communicates the oxidant gas inlet and the oxidant gas outlet and is in a substantially opposite flow to the substantially U-shaped flow path. Preferably, it is configured.

  Furthermore, it is preferable that the first and second separators are constituted by metal separators, and at least a part of the fuel gas channel and the oxidant gas channel is formed by a plurality of protrusions.

  According to the present invention, since the fuel gas flow path constitutes at least two substantially U-shaped flow paths extending along the plane of the first separator, the fuel gas can be reliably supplied to the corners of the electrode surface. Can be supplied to. Thereby, insufficient supply of fuel gas does not occur at the corners of the electrode surface, power generation failure is prevented, and power generation distribution within the electrode surface is easily uniformized.

  Moreover, at the corners of the electrode surface, the flow rate of the fuel gas does not become slow, and the drainage of the condensed water is improved satisfactorily. Furthermore, since the flow rate and flow rate of the fuel gas are made uniform at the fuel gas inlet and the fuel gas outlet, the durability of the electrolyte / electrode structure is improved and the pressure loss is reduced.

  On the other hand, the oxidant gas flow path constitutes a substantially linear flow path extending along the plane of the second separator, and the oxidant gas having a flow rate larger than that of the fuel gas is uniform in the electrode plane. To be supplied. Therefore, with a simple configuration, the power generation distribution in the electrode surface is made uniform, and the drainage of condensed water can be performed smoothly.

  Further, by providing two substantially U-shaped flow paths facing each other, insufficient supply of fuel gas at the corners of the electrode surface is prevented as much as possible, and the fuel gas is smoothly and smoothly distributed within the electrode surface. It can be supplied uniformly.

  Further, the substantially U-shaped flow path that constitutes the fuel gas flow path and the oxidant gas flow path constitute a substantially counter flow, so that the generated water of the oxidant gas flow path is transferred to the fuel gas flow path. Spread effectively. In particular, the generated water that increases toward the oxidant gas flow path on the oxidant gas outlet side is back-diffused to the anode electrode side through the electrolyte membrane, thereby humidifying the fuel gas. For this reason, the fuel cell can be easily operated without error or with low humidification.

  Furthermore, since the first and second separators are formed with a plurality of protrusions by embossing or dimple processing, the desired fuel gas flow path and oxidant gas flow path, as well as the cooling medium flow, can be formed with a simple configuration. A path is easily formed.

  FIG. 1 is an exploded perspective view of a main part of a fuel cell 10 according to the first embodiment of the present invention, and FIG. 2 is a partial cross-sectional explanatory view of the fuel cell 10.

  As shown in FIG. 1, a fuel cell 10 includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) 12 and rectangular first and second metal separators 14 sandwiching the electrolyte membrane / electrode structure 12. 16 are stacked in the direction of arrow A. The 1st and 2nd metal separators 14 and 16 are comprised with the metal thin plate. The electrolyte membrane / electrode structure 12 and the first and second metal separators 14 and 16 are formed in a substantially square shape.

  The fuel cell 10 has a rectangular shape as a whole, and is spaced apart in the left-right direction (arrow B direction) from the first and second sides 18a, 18b that are spaced apart in the vertical direction (arrow C direction) and face each other. And third and fourth sides 18c and 18d facing each other.

  The first side 18a of the fuel cell 10 communicates with each other in the direction of the arrow A, and a first fuel gas inlet 20a for supplying a fuel gas, for example, a hydrogen-containing gas, and for discharging the fuel gas A first fuel gas outlet 20b and a cooling medium outlet 22b for discharging the cooling medium are provided. Similarly, the second side 18b of the fuel cell 10 communicates with each other in the direction of the arrow A, and a second fuel gas inlet 24a for supplying fuel gas and a second fuel gas for discharging the fuel gas. An outlet 24b and a cooling medium inlet 22a for supplying a cooling medium are provided.

  The third side 18c of the fuel cell 10 is provided with first and second oxidant gas inlets 26a, 28a for supplying an oxidant gas, for example, an oxygen-containing gas, in communication with each other in the direction of arrow A. . Similarly, the third side 18c of the fuel cell 10 is provided with first and second oxidant gas outlets 26b and 28b for communicating with each other in the direction of arrow A to discharge the oxidant gas.

  The electrolyte membrane / electrode structure 12 includes, for example, a solid polymer electrolyte membrane (electrolyte) 30 in which a perfluorosulfonic acid thin film is impregnated with water, an anode-side electrode 32 and a cathode that sandwich the solid polymer electrolyte membrane 30. Side electrode 34.

  The anode side electrode 32 and the cathode side electrode 34 are formed in a rectangular shape, and a gas diffusion layer made of carbon paper or the like and porous carbon particles having a platinum alloy supported on the surface are arranged on the surface of the gas diffusion layer. And an electrode catalyst layer applied in this manner. The electrode catalyst layer is bonded to both surfaces of the solid polymer electrolyte membrane 30.

  As shown in FIGS. 1 and 3, the first metal separator 14 has a surface 14 a facing the electrolyte membrane / electrode structure 12 through embossing or dimple processing in a range corresponding to the electrode surface of the anode electrode 32. A plurality of protrusions 36a and 36b are provided so as to alternately protrude on the surface 14b opposite to the surface 14a. A fuel gas flow path 38 is provided between the protrusion 36 a and the anode side electrode 32.

  The fuel gas flow path 38 is connected to the first substantially U-shaped flow path 38a communicating with the first fuel gas inlet 20a and the first fuel gas outlet 20b, and the second fuel gas inlet 24a and the second fuel gas outlet 24b. Two channels are formed with the second substantially U-shaped channel 38b communicating therewith.

  As shown in FIGS. 1 and 4, the second metal separator 16 has a surface 16 a facing the electrolyte membrane / electrode structure 12 through embossing or dimple processing in a range corresponding to the electrode surface of the cathode side electrode 34. A plurality of protrusions 40a and 40b are provided so as to protrude alternately on the surface 16b opposite to the surface 16a. An oxidant gas flow path 42 is provided between the protrusion 40 a and the cathode side electrode 34.

  The oxidant gas flow path 42 communicates with the first and second oxidant gas inlets 26a, 28a and the first and second oxidant gas outlets 26b, 28b, and extends in the direction of arrow C. A path 42a is formed. The substantially linear flow path 42a is configured to flow substantially opposite to the first and second substantially U-shaped flow paths 38a and 38b.

  A cooling medium flow path 44 that connects the cooling medium inlet 22a and the cooling medium outlet 22b through the protrusions 36b and 40b is formed on the surface 16b of the second metal separator 16. The cooling medium flow path 44 is configured to flow the cooling medium from below to above, but the cooling medium may flow from above to below.

  A first seal member 46 is integrally formed on the surfaces 14 a and 14 b of the first metal separator 14 around the outer peripheral end of the first metal separator 14. The first seal member 46 surrounds the first and second fuel gas inlets 20a and 24a, the first and second fuel gas outlets 20b and 24b, and the fuel gas flow path 38 on the surface 14a so as to communicate with each other. On the other hand, the cooling medium inlet 22a, the cooling medium outlet 22b, and the cooling medium flow path 44 are surrounded and communicated with each other by the surface 14b.

  A second seal member 48 is integrally formed on the surfaces 16 a and 16 b of the second metal separator 16 around the outer peripheral end of the second metal separator 16. The second seal member 48 surrounds the first and second oxidant gas inlets 26a and 28a, the first and second oxidant gas outlets 26b and 28b, and the oxidant gas flow path 42 on the surface 16a. On the other hand, the cooling medium inlet 22a, the cooling medium outlet 22b, and the cooling medium flow path 44 are surrounded and communicated with each other by the surface 16b.

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

  As shown in FIG. 1, a fuel gas such as a hydrogen-containing gas, an oxidant gas such as air that is an oxygen-containing gas, and a cooling medium such as pure water, ethylene glycol, or oil are supplied into the fuel cell 10. Is done. For this reason, the fuel gas supplied to the first and second fuel gas inlets 20a and 24a communicating in the direction of arrow A flows from the first fuel gas inlet 20a to the first as shown in FIGS. In addition to being introduced into the fuel gas passage 38 of the metal separator 14, it is introduced into the fuel gas passage 38 from the second fuel gas inlet 24 a.

  For this reason, in the fuel gas flow path 38, the fuel gas supplied from the first fuel gas inlet 20a is discharged to the first fuel gas outlet 20b through the first substantially U-shaped flow path 38a. The fuel gas supplied from the second fuel gas inlet 24a is discharged to the second fuel gas outlet 24b through the second substantially U-shaped channel 38b. Accordingly, the fuel gas moves along the anode side electrode 32 constituting the electrolyte membrane / electrode structure 12.

  On the other hand, the oxidant gas supplied to the first and second oxidant gas inlets 26a, 28a flows into the oxidant gas flow path 42 provided in the second metal separator 16, as shown in FIGS. be introduced. The oxidant gas is discharged to the first and second oxidant gas outlets 26b and 28b through a substantially linear flow path 42a extending substantially linearly in the direction of arrow C (see FIG. 1). As a result, the oxidant gas moves along the cathode-side electrode 34 constituting the electrolyte membrane / electrode structure 12.

  Therefore, in the electrolyte membrane / electrode structure 12, the fuel gas supplied to the anode side electrode 32 and the oxidant gas supplied to the cathode side electrode 34 are consumed by an electrochemical reaction in the electrode catalyst layer to generate power. Is performed (see FIG. 2).

  Next, the consumed fuel gas supplied to the anode side electrode 32 is discharged to the first and second fuel gas outlets 20b and 24b (see FIG. 3). Similarly, the oxidant gas supplied to the cathode side electrode 34 and consumed is discharged to the first and second oxidant gas outlets 26b and 28b (see FIG. 4).

  The cooling medium supplied to the cooling medium inlet 22 a is introduced into the cooling medium flow path 44 formed between the first and second metal separators 14 and 16. The cooling medium cools the electrolyte membrane / electrode structure 12 and then is discharged to the cooling medium outlet 22b (see FIG. 1).

  In this case, in the first embodiment, as shown in FIGS. 1 and 3, the two systems of the first and second systems in which the fuel gas flow path 38 extends along the surface 14 a of the first metal separator 14. The substantially U-shaped flow path 38a, 38b is comprised. For this reason, fuel gas can be reliably supplied also to the corner of the rectangular electrode surface of the anode side electrode 32.

  Thereby, in the anode side electrode 32, the supply of the fuel gas does not occur at the corner of the electrode surface, and the fuel gas can be supplied smoothly and uniformly over the electrode surface. Therefore, the fuel cell 10 has an effect that the power generation failure is prevented and the power generation distribution in the electrode surface is easily made uniform.

  Moreover, at the corners of the electrode surface, the flow rate of the fuel gas does not become slow, and the drainage of the condensed water is improved satisfactorily. Further, since the flow rate and flow velocity of the fuel gas are made uniform at the first and second fuel gas inlets 20a and 24a and the first and second fuel gas outlets 20b and 24b, the durability of the electrolyte membrane / electrode structure 12 is improved. As a result, the pressure loss can be reduced.

  On the other hand, as shown in FIG. 4, the oxidant gas flow path 42 constitutes a substantially straight flow path 42 a extending along the surface 16 a of the second metal separator 16, and has a flow rate compared to the fuel gas. Large oxidant gas is uniformly supplied into the electrode surface of the cathode side electrode 34. Therefore, with a simple configuration, the power generation distribution in the electrode surface is made uniform, and the drainage of condensed water can be performed smoothly.

  Further, the first and second substantially U-shaped flow paths 38a and 38b constituting the fuel gas flow path 38 and the substantially straight flow path 42a constituting the oxidant gas flow path 42 constitute a substantially counter flow. doing. For this reason, the produced water generated in the oxidant gas flow path 42 is effectively diffused into the fuel gas flow path 38, and there is an advantage that the fuel cell 10 can be easily operated without error or with low humidity.

  Furthermore, the first and second metal separators 14 and 16 are formed with a plurality of protrusions 36a, 36b, 40a and 40b by embossing or dimple processing. Thereby, the desired fuel gas flow path 38, the oxidant gas flow path 42, and the cooling medium flow path 44 are easily formed with a simple configuration.

  FIG. 5 is an exploded perspective view of a main part of a fuel cell 60 according to the second embodiment of the present invention. The same components as those of the fuel cell 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The fuel cell 60 includes rectangular first and second metal separators 62 and 64 that sandwich the electrolyte membrane / electrode structure 12. As shown in FIGS. 5 and 6, the first metal separator 62 includes a plurality of first and second fuel gas inlets 20a and 24a and a plurality of first and second fuel gas outlets 20b and 24b. The protrusions 66a and 66b protrude alternately in the reverse direction. A plurality of wave-like channels 68 extending in the direction of the arrow C are formed between the protrusions 66a and 66a that are separated in the direction of the arrow C (within the range of the distance H).

  A fuel gas channel 70 is provided between the protrusion 66 a and the wave-like channel 68 and the anode side electrode 32. The fuel gas channel 70 is connected to the first substantially U-shaped channel 70a communicating with the first fuel gas inlet 20a and the first fuel gas outlet 20b, and the second fuel gas inlet 24a and the second fuel gas outlet 24b. Two channels are formed with the second substantially U-shaped channel 70b communicating with each other.

  As shown in FIGS. 5 and 7, the second metal separator 64 includes a plurality of first and second fuel gas inlets 20a and 24a and a plurality of first and second fuel gas outlets 20b and 24b. The protrusions 72a and 72b protrude alternately in the reverse direction. A plurality of wave-like channels 74 extending in the direction of the arrow C are formed between the protrusions 72a and 72a that are separated in the direction of the arrow C (within the range of the distance H).

  On the surface 64a of the second metal separator 64, there is an oxidant gas flow channel 76 that is positioned between the projection 72a and the wavy flow channel 74 and the cathode side electrode 34 and extends substantially linearly in the direction of arrow C. Provided. The oxidant gas flow path 76 is configured in a substantially opposite flow to the first and second substantially U-shaped flow paths 70a and 70b.

  A cooling medium flow path 78 that connects the cooling medium inlet 22a and the cooling medium outlet 22b through the protrusions 66b and 72b is formed on the surface 64b of the second metal separator 64. As shown in FIG. 8, the cooling medium flow path 78 is formed by connecting gaps between the wavy flow paths 68 and 74 of the first and second metal separators 62 and 64.

  In the second embodiment configured as described above, the fuel gas and the oxidant gas can be reliably supplied also to the corners of the electrode surfaces of the anode side electrode 32 and the cathode side electrode 34, and the electrode surface The same effects as those of the first embodiment can be obtained, such as the power generation distribution in the inside being easily made uniform. In addition, the fuel gas channel 70 and the oxidant gas channel 76 have corrugated channels 68 and 74, and the fuel gas and the oxidant gas are more smoothly and reliably distributed along the corrugated channels 68 and 74. The power generation efficiency can be easily improved.

  In the first and second embodiments, the fuel gas flow path 38 constitutes two systems of first and second substantially U-shaped flow paths 38a and 38b, and the fuel gas flow path 70 has 2 Although the 1st and 2nd substantially U-shaped flow paths 70a and 70b of a system | strain are comprised, it is not limited to this. For example, fuel gas flow paths (not shown) that constitute three or more substantially U-shaped flow paths may be used. Further, the anode side electrode 32 and the cathode side electrode 34 are not limited to a rectangular shape, and can be configured in various shapes such as a polygonal shape.

It is a principal part disassembled perspective view of the fuel cell which concerns on the 1st Embodiment of this invention. It is a partial cross section explanatory view of the fuel cell. It is front explanatory drawing of the 1st metal separator which comprises the said fuel cell. It is front explanatory drawing of the 2nd metal separator which comprises the said fuel cell. It is a principal part disassembled perspective view of the fuel cell which concerns on the 2nd Embodiment of this invention. It is front explanatory drawing of the 1st metal separator which comprises the said fuel cell. It is front explanatory drawing of the 2nd metal separator which comprises the said fuel cell. It is a perspective explanatory view of a wave-like channel provided in the first and second metal separators. It is front explanatory drawing of the separator plate which concerns on patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 60 ... Fuel cell 12 ... Electrolyte membrane and electrode structure 14, 16, 62, 64 ... Metal separator 18a-18d ... Side 20a, 24a ... Fuel gas inlet 20b, 24b ... Fuel gas outlet 22a ... Cooling medium inlet 22b ... Coolant outlet 26a, 28a ... Oxidant gas inlet 26b, 28b ... Oxidant gas outlet 30 ... Solid polymer electrolyte membrane 32 ... Anode side electrode 34 ... Cathode side electrode 36a, 36b, 40a, 40b, 66a, 66b, 72a, 72b ... protrusions 38, 70 ... fuel gas channels 38a, 38b, 70a, 70b ... substantially U-shaped channels 42, 76 ... oxidant gas channels 42a ... substantially linear channels 44 ... cooling medium channels 74 ... Wavy channel

Claims (4)

An electrolyte / electrode structure in which an anode side electrode and a cathode side electrode are provided on both sides of an electrolyte, and first and second separators sandwiching the electrolyte / electrode structure, the anode side electrode and the first electrode A fuel gas passage for supplying fuel gas along the electrode surface is formed between the separator and an oxidant gas along the electrode surface between the cathode-side electrode and the second separator. A fuel cell in which an oxidant gas flow path is formed,
The fuel gas flow path constitutes at least two substantially U-shaped flow paths extending along the plane of the first separator,
The fuel cell according to claim 1, wherein the oxidant gas flow path constitutes a substantially straight flow path extending along a plane of the second separator. The fuel cell according to claim 1, wherein the first separator is configured in a rectangular shape,
A fuel gas inlet and a fuel gas outlet are formed on the first side and the second side facing each other, respectively, so that two substantially U-shaped parts facing each other are provided in the plane of the first separator. A fuel cell, characterized in that a flow path is provided. The fuel cell according to claim 2, wherein the second separator is configured in a rectangular shape,
An oxidant gas inlet is formed on the third side that intersects the first and second sides, and an oxidant gas outlet is formed on the fourth side opposite to the third side. And
The fuel cell according to claim 1, wherein the oxidant gas flow path is configured to communicate with the oxidant gas inlet and the oxidant gas outlet and to be substantially opposite to the substantially U-shaped flow path. The fuel cell according to any one of claims 1 to 3, wherein the first and second separators are constituted by metal separators,
At least a part of the fuel gas channel and the oxidant gas channel is formed by a plurality of protrusions.

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