JP2017117642A - Fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve drainage of a fuel battery.SOLUTION: A fuel battery comprises: an electric power module having a film electrode assembly and a first and a second gas diffusion layers arranged on both sides of the film electrode assembly; a first separator that is arranged on the first gas diffusion layer of the electric power module; a second separator that is arranged on the second gas diffusion layer of the electric power module; and a resin sheet that is arranged on an outer side of the electric power module between both separators, and seals between both separators. Each of them comprises a manifold hole constructing a manifold for distributing a reaction gas to the electric power module. The resin sheet comprises a passage groove for communicating an inner space to which the first gas diffusion layer is arranged and the manifold. The passage groove includes a taper form passage cross section that becomes wider as a direction toward the first separator from the second separator, and has a form in which the first separator side is opened.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fuel cell.

  In general, a fuel cell includes a power generation module in which gas diffusion layers are arranged on both surfaces of a membrane electrode assembly, and two separators that sandwich the power generation module. The outside of the power generation module between the two separators is sealed by a resin seal member (see Patent Documents 1 and 2). Patent Document 1 discloses a configuration in which an opening communicating with an internal space in which a gas diffusion layer is disposed is formed in a resin frame member as a seal member.

JP 2014-63727 A JP 2013-251253 A

  In the prior art described above, the manifold penetrating between a pair of separators and the opening may be connected by a communication hole. In this configuration, the upper and lower surfaces of the communication hole are covered with the separator. For this reason, the water produced | generated with the fuel cell adhered to both separators, and there existed a problem which the drainage property from a fuel cell deteriorated.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) One embodiment of the present invention is a fuel cell. The fuel cell includes a power generation module having a membrane electrode assembly and first and second gas diffusion layers disposed on both sides of the membrane electrode assembly, and the first gas diffusion layer of the power generation module. The first separator disposed on the side, the second separator disposed on the second gas diffusion layer side of the power generation module, and the power generation between the first separator and the second separator A resin sheet that is disposed outside the module and seals between the first separator and the second separator. Each of the first separator, the resin sheet, and the second separator includes a manifold hole that forms a manifold for distributing reaction gas to the power generation module. The resin sheet includes a flow channel for communicating the internal space in which the first gas diffusion layer is disposed and the manifold. The channel groove has a tapered channel cross section that widens in the direction from the second separator toward the first separator, and has a shape in which the first separator side is open.

  According to the fuel cell of this aspect, the channel groove has a tapered channel cross section that widens in the direction from the second separator toward the first separator, and the first separator side is open. Therefore, the generated water generated in the power generation module tends to be biased toward the first separator in the flow channel formed in the resin sheet. This is because each separator has hydrophilicity and the resin sheet has water repellency. Since the generated water is biased toward the first separator, a space for allowing the reaction gas to pass can be sufficiently secured in the channel groove. As a result, the drainage of the fuel cell can be improved.

It is explanatory drawing which shows schematic structure of the fuel cell system in 1st Embodiment of this invention. It is the schematic plan view which looked at the anode side separator from the opposite side to MEGA. It is explanatory drawing which shows the AA cross section of FIG. It is explanatory drawing which shows the AA cross section before joining. It is explanatory drawing which shows the AA cross section after electric power generation. It is principal part sectional drawing of the fuel battery cell as a reference example. It is explanatory drawing which shows the cross section of the fuel cell in 2nd Embodiment.

A. First embodiment:
FIG. 1 is an explanatory diagram showing a schematic configuration of a fuel cell system 10 according to the first embodiment of the present invention. The fuel cell system 10 includes a fuel cell stack 100 as a fuel cell. The fuel cell stack 100 includes an end plate 110, an insulating plate 120, a current collecting plate 130, a plurality of fuel cell units (hereinafter also simply referred to as “cells”) 140, a current collecting plate 130, an insulating plate 120, The end plate 110 has a stack structure that is laminated in this order. Note that the stacking direction of the cells 140 is a direction X perpendicular to the vertical direction Y in this embodiment. The front-back direction in the figure perpendicular to the vertical direction Y and the stacking direction X is the front-rear direction Z. The front-rear direction Z is referred to as such because it corresponds to the front-rear direction of the vehicle when the fuel cell system 10 of the present embodiment is mounted on the vehicle.

  Hydrogen as fuel gas is supplied to the fuel cell stack 100 from a hydrogen tank 150 that stores high-pressure hydrogen via a shut valve 151, a regulator 152, and a pipe 153. The fuel gas (anode off gas) not used in the fuel cell stack 100 is discharged to the outside of the fuel cell stack 100 via the discharge pipe 163. The fuel cell system 10 may have a recirculation mechanism that recirculates the anode off gas to the pipe 153 side. The fuel cell stack 100 is also supplied with air as an oxidant gas via the air pump 160 and the pipe 161. The oxidant gas (cathode off gas) that has not been used in the fuel cell stack 100 is discharged to the outside of the fuel cell stack 100 via the discharge pipe 154. The fuel gas and the oxidant gas are also called reaction gas.

  Further, the cooling medium cooled by the radiator 170 is supplied to the fuel cell stack 100 via the water pump 171 and the pipe 172 in order to cool the fuel cell stack 100. The cooling medium discharged from the fuel cell stack 100 is circulated to the radiator 170 via the pipe 173. As the cooling medium, for example, water, antifreeze water such as ethylene glycol, air, or the like is used. In this example, water (also referred to as “cooling water”) is used as the cooling medium.

  Each cell 140 provided in the fuel cell stack 100 includes a membrane electrode gas diffusion layer assembly (MEGA) 30 as a power generation module, and a pair of separators 40 and 50 sandwiching the MEGA 30. ing. The MEGA 30 includes a membrane electrode assembly (MEA) 31 and a pair of gas diffusion layers 32 and 33 disposed on both surfaces of the MEA 31. One separator 50, that is, the anode-side separator 50, includes a plurality of streaky fuel gas passage grooves 52 on the MEGA 30 side surface, and a plurality of streaky cooling medium passage grooves 54 on the surface opposite to the MEGA 30. Is provided. The other separator 40, that is, the cathode-side separator 40 includes a plurality of oxidant gas flow channel grooves 42 in a streak shape on the surface on the MEGA 30 side.

  Each cell 140 further includes a resin sheet 80 disposed on the outer side (outer periphery) in the surface direction (YZ direction in the drawing) of the MEGA 30 between the anode side separator 50 and the cathode side separator 40. The resin sheet 80 is molded using a thermoplastic resin so as to form a plate shape and a frame shape, and seals between the anode side separator 50 and the cathode side separator 40 in a state where the MEGA 30 is held in the center region. As the resin sheet 80, for example, a resin such as PE, PP, PET, PEN can be used. The resin sheet 80 is bonded to the separators 40 and 50 by melting the surface layer portion of the resin sheet 80 in the manufacturing process and curing it after the curing. The resin sheet 80 has water repellency.

  FIG. 2 is a schematic plan view of the anode separator 50 of the cell 140 as viewed from the side opposite to the MEGA 30. In FIG. 2, the front / back direction is the stacking direction X, the up / down direction is the vertical direction Y, and the left / right direction is the front / rear direction Z. The anode-side separator 50 and the cathode-side separator 40 are configured by members having gas barrier properties and electrical conductivity. For example, a carbon-made member such as dense carbon in which carbon particles are compressed and gas-impermeable, It is made of a press-molded metal member such as stainless steel or titanium steel. The separators 40 and 50 formed of these materials are hydrophilic. In the present embodiment, the separators 40 and 50 are metal press separators.

  A fuel gas inlet manifold 62, a coolant outlet manifold 78, and an oxidant gas inlet manifold 72 are arranged in order from the top along the vertical direction Y at one edge of the anode separator 50 in the front-rear direction Z. Yes. On the other hand, an oxidant gas outlet manifold 74, a cooling medium inlet manifold 76, and a fuel gas outlet manifold 64 are arranged along the vertical direction Y in order from the top at the other end edge. . The fuel gas inlet manifold 62 and the fuel gas outlet manifold 64, the oxidant gas inlet manifold 72 and the oxidant gas outlet manifold 74, and the cooling medium inlet manifold 76 and the cooling medium outlet manifold 78 are outer edge portions on both sides in the front-rear direction Z. Are arranged so as to face each other. Each manifold 62, 64, 72, 74, 76, 78 corresponds to a “manifold hole” in one embodiment of the present invention described in the “Summary of the Invention” column.

  The fuel gas supplied through the fuel gas pipe 153 (FIG. 1) is distributed to the fuel gas flow channel grooves 52 (FIG. 1) of the respective cells 140 by the fuel gas inlet manifold 62. Thereafter, the fuel gas that has not been used in the fuel gas passage groove 52 is collected by the fuel gas outlet manifold 64 and discharged to the outside of the fuel cell stack 100 through the discharge pipe 163 (FIG. 1). Further, the oxidant gas supplied via the oxidant gas pipe 161 (FIG. 1) is distributed to the oxidant gas flow channel 42 (FIG. 1) of each cell 140 by the oxidant gas inlet manifold 72. . Thereafter, the oxidant gas that has not been used in the oxidant gas passage groove 42 is collected by the oxidant gas outlet manifold 74 and discharged to the outside of the fuel cell stack 100 via the discharge pipe 154 (FIG. 1).

  The cooling medium inlet manifold 76, the cooling medium flow channel 54, and the cooling medium outlet manifold 78 communicate with each other in the front-rear direction Z on the plane of the anode side separator 50 as viewed from the side opposite to the MEGA 30. A flow path surface 190 is formed. The cooling medium supplied via the cooling medium pipe 172 (FIG. 1) is distributed to the cooling medium flow channel 54 of each cell 140 by the cooling medium inlet manifold 76. Thereafter, the cooling medium is collected by the cooling medium outlet manifold 78 and discharged to the outside of the fuel cell stack 100 via the pipe 173 (FIG. 1).

  Each manifold 62, 64, 72, 74, 76, 78 has a substantially rectangular opening. The cathode side separator 40 and the resin sheet 80 are also provided with similar manifold holes, and each manifold (manifold hole) 62, 64, 72, 74, 76, 78 penetrates the fuel cell stack 100 in the stacking direction X. A flow path (manifold) is formed.

  A plurality of convex portions 50 m are provided between the coolant flow path surface 190 and the fuel gas inlet manifold 62 on a plane viewed from the side of the anode separator 50 opposite to the MEGA 30. The convex portion 50m is formed by press molding. The convex portion 50m becomes a concave portion (groove) when viewed from the MEGA 30 side (that is, the back surface side in FIG. 2) of the anode-side separator 50, and the internal space SP in which the anode-side gas diffusion layer 33 of the MEGA 30 is disposed (FIG. 1). And a part of the communication hole 90 (FIG. 3) that communicates with the fuel gas inlet manifold 62. Although the number of the convex portions 50m constituting the communication hole 90 is three in the drawing, the number is not limited to three, and may be other numbers (1, 2, 4 or more).

  FIG. 3 is an explanatory view showing an AA section of the anode-side separator 50 shown in FIG. The AA cross section is a portion between the fuel gas inlet manifold 62 and the anode side gas diffusion layer 33 (FIG. 1). As shown in the figure, the anode-side separator 50 is formed with the above-described convex portion 50m, and a flow channel P1 extending in the front-rear direction Z is formed inside thereof. The cathode separator 40 facing the anode separator 50 is flat in the vicinity of the AA cross section.

  Between the anode side separator 50 and the cathode side separator 40, the resin sheet 80 mentioned above is arrange | positioned, and the resin sheet 80 appears also in this AA cross section. As shown in the drawing, the resin sheet 80 is formed with a plurality of resin sheet-side flow channel grooves P2. Each resin sheet side channel groove P2 is paired with each of the channel grooves (hereinafter referred to as “separator side channel grooves”) P1 on the anode side separator 50 side, and the anode side gas diffusion layer 33 is disposed. A communication hole 90 connecting the internal space SP and the fuel gas inlet manifold 62 is formed.

  As shown in the figure, the resin sheet-side flow channel P2 has a taper-shaped flow channel cross section that widens in the direction from the cathode separator 40 toward the anode separator 50. The direction from the cathode side separator 40 to the anode side separator 50 is a direction from the lower side to the upper side in the drawing in the stacking direction X. The anode side separator 50 side of the resin sheet side flow channel P2, that is, the upper side in the drawing is in an open state (opened state), and the cathode side separator 40 side of the resin sheet side flow channel P2 is shown. The lower side in the state is closed by the thin film layer 80a.

  The resin sheet 80 disposed between the separators 40 and 50 is heated and applied with a load after application at the time of cell bonding, so that the surface layer portion melts and exhibits an adhesive function. As shown in FIG. 4, before the cell bonding, the surface of the cathode separator 40 and the resin sheet side flow channel P2 are in communication with each other, that is, the cathode side separator 40 is exposed to the resin sheet side flow channel P2 side. In this state, the amount of heat, load, and bonding time applied at the time of bonding are increased compared to the case of simply bonding between the separators 40 and 50 and the resin sheet 80. The thin film layer 80a (FIG. 3) can be formed such that the surface layer portion is more dissolved. As a result, the portion of the cathode separator 40 that communicates with the resin sheet side flow channel P2 can be covered with the thin film layer 80a. The thin film layer 80a is formed of the same material as the resin sheet 80. In the present embodiment, the amount of heat, the load, and the bonding time are adjusted so that the thickness of the thin film layer 80a is several tens of μm. The thin film layer 80a thus formed has water repellency.

  The cross-sectional shape shown in FIG. 3 is the configuration of the main part of the communication hole 90, and the size of the aperture is small in the part of the communication hole 90 on the side close to the internal space SP where the anode-side gas diffusion layer 33 is arranged. And connected to the internal space SP.

  As shown in FIG. 2, a convex portion 50n is also provided on the fuel gas outlet manifold 64 side. The protrusion 50n has the same shape as the protrusion 50m of the fuel gas inlet manifold 62 described above, and the communication hole described above is provided between the internal space in which the anode gas diffusion layer 33 is disposed and the fuel gas outlet manifold 64. A communication hole having the same configuration as that of 90 is provided. The same applies between the oxidant gas inlet manifold 72 and the internal space where the cathode side gas diffusion layer 32 is disposed, and between the internal space where the cathode side gas diffusion layer 32 is disposed and the oxidant gas outlet manifold 74. The communication hole of the structure is provided.

  In the fuel cell stack 100 configured as described above, the anode-side separator 50 corresponds to the “first separator” in one embodiment of the present invention described in the “Summary of the Invention” section, and the cathode-side separator 40 is “ The anode-side gas diffusion layer 33 corresponds to a “first gas diffusion layer”, and the cathode-side gas diffusion layer 32 corresponds to a “second gas diffusion layer”.

  As described above in detail, according to the fuel cell stack 100 of the present embodiment, the communication hole 90 is provided between the internal space SP (FIG. 1) in which the anode side gas diffusion layer 33 is disposed and the fuel gas inlet manifold 62. Tied by. A part of the communication hole 90 is constituted by a resin sheet side flow channel P2 provided in the resin sheet 80. The resin sheet side flow channel P2 is directed from the cathode side separator 40 toward the anode side separator 50. The anode-side separator 50 side has an open shape. In addition, since the anode-side separator 50 has hydrophilicity and the resin sheet 80 has water repellency, the generated water generated in the MEGA 30 tends to be biased toward the anode-side separator 50 side.

  FIG. 5 is an explanatory diagram showing an AA cross section of the fuel battery cell 140 after power generation. After the power generation of the fuel cell stack 100, the generated water W is biased toward the anode-side separator 50 and is held in the separator-side flow channel P1. For this reason, the resin sheet side flow channel P2 formed in the resin sheet 80 is in a sufficiently opened state. Therefore, when the fuel cell system 10 is started below the freezing point, the communication hole 90 is not blocked, so that the startability can be improved. In addition, since the startability can be improved without increasing the number of parts, the number of parts can be reduced and the productivity can be improved.

  FIG. 6 is a cross-sectional view of a main part of a fuel cell 940 as a reference example. The cross section of the main part corresponds to the AA cross section of the first embodiment. In the fuel cell 900 of the reference example, the resin sheet 980 is disposed between the anode side separator 950 and the cathode side separator 940, and the resin sheet side flow channel P92 provided in the resin sheet 980 has a rectangular flow shape. It has a road cross section. The anode side separator 950 side of the resin sheet side flow channel P92 is open, and the cathode side separator 940 side of the resin sheet side flow channel P92 is also open. According to this configuration, the resin sheet side channel groove P92 is in contact with the surfaces of both separators 950 and 940, and both separators 50 and 40 have hydrophilicity. The communication hole is blocked by the generated water W. Therefore, according to the fuel cell 900 of the reference example, the startability is deteriorated.

B. Second embodiment:
FIG. 7 is an explanatory view showing a cross section of the fuel battery cell 240 in the second embodiment. This cross section shows a cross section at the same position as the AA cross section shown in FIG. The fuel cell 240 of the second embodiment is different from the fuel cell 140 (FIG. 3) of the first embodiment in the configuration of the resin sheet side flow channel P22 provided in the resin sheet 280, and the remaining Match in terms of. In the second embodiment, the same components as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

  The resin sheet side channel groove P2 in the first embodiment has a tapered channel cross section that widens in the direction from the cathode side separator 40 to the anode side separator 50, and the anode side separator 50 side is open. The cathode separator 40 side is covered with the thin film layer 80a. On the other hand, as shown in FIG. 7, the resin sheet side flow channel groove P <b> 22 in the second embodiment has a taper-shaped flow channel cross section that widens in the direction from the cathode side separator 40 to the anode side separator 50. The anode side separator 50 side and the cathode side separator 40 side are open.

  In the fuel cell 240 according to the second embodiment, the resin sheet side flow channel P92 is in contact with the surfaces of both separators 40 and 50, but widens in the direction from the cathode side separator 40 toward the anode side separator 50. Since it has a tapered channel cross section, the contact area that becomes hydrophilic on the cathode separator 40 side can be reduced. For this reason, in the fuel cell 240 in the second embodiment, the generated water tends to be biased toward the anode separator 50 side, and the drainage can be improved as in the first embodiment.

  The present invention is not limited to the above-described embodiment, and can be realized with various configurations without departing from the spirit of the present invention. For example, the technical features in the embodiments corresponding to the technical features in each embodiment described in the summary section of the invention are intended to solve part or all of the above-described problems, or one of the above-described effects. In order to achieve part or all, replacement or combination can be appropriately performed. Moreover, elements other than the elements described in the independent claims among the constituent elements in the respective embodiments described above are additional elements and can be omitted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell system 30 ... Membrane electrode gas diffusion layer assembly (MEGA)
31 ... Membrane electrode assembly (MEA)
32 ... Cathode side gas diffusion layer 33 ... Anode side gas diffusion layer 40 ... Cathode side separator 42 ... Oxidant gas passage groove 50 ... Anode side separator 52 ... Fuel gas passage groove 54 ... Cooling medium passage groove 62 ... Fuel gas Inlet manifold 64 ... Fuel gas outlet manifold 72 ... Oxidant gas inlet manifold 74 ... Oxidant gas outlet manifold 76 ... Cooling medium inlet manifold 78 ... Cooling medium outlet manifold 80 ... Resin sheet 80a ... Thin film layer 90 ... Communication hole 100 ... Fuel cell Stack 110 ... End plate 120 ... Insulating plate 130 ... Current collecting plate 140 ... Fuel cell 150 ... Hydrogen tank 151 ... Shut valve 152 ... Regulator 153 ... Piping 154 ... Exhaust piping 160 ... Air pump 161 ... Piping 163 ... Exhaust piping 170 ... Radiator 171 ... Otaponpu 172 ... pipe 173 ... pipe 190 ... cooling medium flow path 240 ... fuel cell 280 ... resin sheet SP ... internal space W ... generated water anode gas diffusion layer is disposed

Claims (1)

A fuel cell,
A power generation module having a membrane electrode assembly, and first and second gas diffusion layers disposed on both sides of the membrane electrode assembly,
A first separator disposed on the first gas diffusion layer side of the power generation module;
A second separator disposed on the second gas diffusion layer side of the power generation module;
A resin sheet that is disposed outside the power generation module between the first separator and the second separator, and seals between the first separator and the second separator;
With
Each of the first separator, the resin sheet, and the second separator includes a manifold hole that constitutes a manifold for distributing reaction gas to the power generation module,
The resin sheet includes a channel groove for communicating the internal space in which the first gas diffusion layer is disposed and the manifold.
The channel groove is
It has a tapered channel cross section that widens in the direction from the second separator toward the first separator, and the first separator side is open.
Fuel cell.

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