JP3123992B2 - Polymer electrolyte fuel cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polymer electrolyte fuel cell, and more particularly to a technique for improving gas distribution performance.

[0002]

2. Description of the Related Art In a polymer electrolyte fuel cell, a cell in which a cathode is arranged on one side of a solid polymer membrane and an anode is arranged on the other side is composed of a pair of plate members in which gas channels are formed. Many of the sandwiched basic structures that are put into practical use are configured by stacking a large number of unit cells having such a basic structure. During operation, air as an oxidant is supplied to the flow path on the cathode side, and fuel gas is supplied to the flow path on the anode side, and power is generated by an electrochemical reaction.

[0003] In a polymer electrolyte fuel cell, it is necessary to keep the solid polymer membrane humidified during operation in order to secure the ionic conductivity. Therefore, conventionally, air or fuel gas is supplied by humidification. The method of moisturizing the solid polymer membrane by using a method is often used. Alternatively, for example, as disclosed in Japanese Patent Application Laid-Open No. 5-41230, fuel gas is supplied to each anode-side flow path. A polymer electrolyte fuel cell has also been developed that can distribute fuel gas and liquid water and distribute them together, thereby efficiently supplying fuel gas to the anode, keeping the polymer membrane moist, and cooling the battery. ing.

In order to obtain excellent cell characteristics in a fuel cell, it is necessary to distribute fuel gas over the entire anode. Therefore, in the polymer electrolyte fuel cell of this type, it is desired that the anode-side flow path is not blocked by water and the flow of the fuel gas is not stopped. In consideration of this point, conventionally, the fuel gas and water are circulated downward with the flow path directed vertically, and then discharged to the outside of the battery via a common pipe below the battery. Nevertheless, the fuel gas exhaust gas, the solid flow channel substrate, and the liquid water phase are in contact with the downstream end of the anode-side flow channel, so that a meniscus of water is formed by capillary action. Therefore, there is a problem that the fuel gas does not easily flow.

FIG. 8 is a schematic diagram showing a state in which a meniscus is formed at the lower end of the anode-side flow path and the gas flow is blocked. When such a meniscus 800 is formed, the flow path 801 is closed, so that the supply of the fuel gas to the anode becomes uneven. As a measure to prevent the flow path from being blocked by water, it is conceivable to set the flow path width to be wider so that the capillary phenomenon does not occur. As a result, the electrical resistance in the fuel cell increases, which is not desirable.

Further, it is conceivable to supply the fuel gas at a high pressure and to distribute the fuel gas at a high speed in the flow path. This is not desirable for realizing a simple system. In order to solve this problem, the present applicant has previously arranged, as shown in FIG. 9, a carbon paper 902 subjected to a water-repellent treatment on the downstream side of the anode-side substrate 900 in correspondence with the plurality of anode-side channels 901. Then, a technique has been proposed in which gas is selectively permeated from the carbon paper 902 and the remaining water is absorbed and discharged by a water-absorbing substrate 903 provided in a discharge manifold further downstream (Japanese Patent Application No. Hei 9-188572).
Specification and drawings).

[0007] Thus, the problem that the gas flow path is blocked due to the formation of the meniscus can be solved.

[0008]

By the way, in order to realize stable power generation, the configuration described in the specific example of the above specification prevents unreacted gas from flowing out from the water discharge port and reduces the carbon paper. By discharging the gas from only the fine holes 902, the gas distribution in one anode-side flow path 901 is uniformly performed. That is, the water-absorbing substrate 903 is disposed so as to cover the entire outlet of the flow channel, and the lower end of the flow channel is sealed (water-sealed) with water to prevent the outflow of gas.

This technique has the advantage that the gas can be distributed relatively uniformly to the cells, while the water-absorbing substrate 9 has the advantage.
03 is the anode side flow path 90 at the outlet side of the flow path 901.
1 is provided across the entirety, so that there are the following problems. That is, the porous carbon material used to form the anode-side flow path substrate is generally formed into a flat plate by sintering fine carbon powder, and the flow path is formed by cutting. For this reason, the surface may be peeled off by supplying water or gas, and there is a high possibility that the peeled carbon is clogged on the water-absorbing substrate provided in the drainage manifold. Further, even when a substrate that is formed by molding a conductive material with a resin, for example, a so-called molded substrate is used as a substrate that is unlikely to be peeled, if dust is floating in water, clogging due to the dust occurs. Results.

When dust such as carbon powder is clogged in this way, water may be pushed up to the upstream side and may cover the carbon paper 902 that selectively discharges gas. Gas cannot be discharged effectively. Therefore, the present invention has been made in view of such a problem, and an object of the present invention is to provide a polymer electrolyte fuel cell capable of efficiently discharging gas and efficiently discharging water.

[0011]

In order to achieve the above object, the present invention provides a cell comprising a solid polymer membrane having a cathode and an anode, wherein the cell has an anode-side flow path formed opposite to the anode. 1 plate and a second plate having a cathode-side flow path formed opposite to the cathode, so that fuel gas and water are supplied to the anode-side flow path and the cathode-side flow path is provided. A fuel cell, wherein the oxidizing gas is supplied to the polymer electrolyte fuel cell to generate power, wherein the first plate extends from the anode-side flow path downstream of a terminal end of the anode in a fuel gas flow direction. A member having a contact angle of water on the surface equal to or greater than the contact angle of water on the inner wall of the plate of the extended flow passage, at a position corresponding to the bottom surface of the extended flow passage, Downstream of the member, a gas outlet The contact angle of water on the surface is equal to the contact angle of water on the inner wall of the plate of the extension flow path at a position corresponding to the bottom surface of the extension flow path on the downstream side of the gas discharge port. Alternatively, a small member is provided, and a water outlet communicating with the extension flow path is opened downstream of the member.

Alternatively, the second plate has an extension passage extending from the cathode-side passage downstream of an end of the cathode in a flow direction of the oxidizing gas, and the second plate has an extension passage. At a position corresponding to the bottom surface, a member whose surface contact angle with water is equal to or greater than the contact angle of water with the inner wall of the plate of the extension flow path is arranged, and a gas outlet is opened downstream of the member. And further, on the downstream side of the gas outlet,
At a position corresponding to the bottom surface of the extension flow path, a member having a contact angle of water on the surface equal to or smaller than a contact angle of water on the inner wall of the plate of the extension flow path is arranged. A water outlet communicating with the installation channel is established.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment] A polymer electrolyte fuel cell according to an embodiment of the present invention will be specifically described with reference to the drawings. FIG. 1 is an assembly diagram of a cell unit 100 constituting a polymer electrolyte fuel cell 1 (hereinafter, simply referred to as “fuel cell 1”) according to the present embodiment.

As shown in FIG.
Is one side of the rectangular frame 10 (the top side in FIG. 1)
The cathode 22 and the anode 23 are formed on the solid polymer film 21.
And a plurality of cathode-side flow paths 311
Are fitted in parallel with the cathode-side flow path substrate 30 in which a plurality of anode-side flow paths 400 are formed in parallel on the other surface side (the lower surface side in FIG. 1) of the frame 10. The side flow path substrate 40 and the partition plate 50 are fitted. In FIG. 1, the anode 23 is indicated by a broken line because it is located on the back side of the solid polymer film 21.

The cell 20 is held in a state of being sandwiched between the cathode-side flow path substrate 30 and the anode-side flow path substrate 40, and the anode-side flow paths 400 are arranged in a direction indicated by a white arrow in FIG. The fuel gas flows to the cathode side flow paths 311.
Air flows in the direction indicated by the thick arrow in FIG.
The power is generated by. As the fuel gas, hydrogen gas or a natural gas containing hydrogen as a main component, or a reformed gas such as propane, butane, or methanol can be used.

The fuel cell 1 has a structure in which a predetermined number of the cell units 100 are stacked, and both ends thereof are sandwiched between a pair of end plates 71 and 72 (not shown in FIG. 1, see FIG. 3). The frame body 10 has a notch for fitting the cell 20 and the cathode-side flow path substrate 30 into the center of the rectangular plate body in the fuel gas flow direction on one surface side (the upper surface side in FIG. 1). On the other side (lower side in FIG. 1), a concave portion 103 is formed to fit the anode-side flow path substrate 40 and the partition plate 50. A window 102 is formed so that the flow path substrate 40 and the anode 23 can come into contact with each other, and is formed by injection molding a plastic material.

A pair of manifold holes 111 for introducing water from the outside are provided in an upstream portion of the frame body 10 in the fuel gas flow direction, and an anode-side flow passage 40 communicating with the manifold holes 111.
, And a pair of manifold holes 112 for introducing fuel gas from outside.
, And a slot 122 for distributing the fuel gas to the anode-side flow paths 400... In the downstream portion, a pair of manifold holes 113 for leading out unreacted fuel gas to the outside, and a groove communicating with the manifold holes 113 and discharging fuel gas from the anode-side flow paths 400 to the manifold holes 113 are provided. A hole 123 and a pair of manifold holes 114 for leading water to the outside, and a slot 124 for communicating with the manifold holes 114 and discharging water from the anode-side flow paths 400 to the manifold holes 114 are formed.

Each of the slots 121 to 124 is formed in a direction orthogonal to the anode-side flow paths 400, and both ends correspond to the manifold holes 111 to 114, respectively. The solid polymer film 21 is a thin film made of perfluorocarbon sulfonic acid. The cathode 22 and the anode 23 are layers each having a predetermined thickness made of platinum-supporting carbon, and are tightly formed at the center of the solid polymer film 21 by hot pressing.

The cathode-side flow path substrate 30 is configured by fitting a flow path substrate body 310 into a frame 300. The flow path substrate body 310 is a plate-shaped member made of a porous carbon material, and has flow paths 311 through which air flows, on a surface (a lower surface in FIG. 1) facing the cathode 22.

The frame body 300 has a shape in which a window 303 is opened in the center of a rectangular flat plate, is made of a plastic material, and has a surface opposite to the cathode 22 side (an upper surface side in FIG. 1).
The flow paths 301 for introducing air into the flow paths 311.
And a flow path 302 for extracting air from the flow paths 311.
... are formed. Note that a gasket 61 is interposed between the cell 20 and the cathode-side flow path substrate 30,
A gasket 62 is interposed between the gasket 62 and the notch 101.

The anode-side flow path substrate 40 is a rectangular carbon porous body slightly smaller in size than the frame body 10, and has a plurality of anode-side flow paths 400 formed in parallel with each other. Ribs 401 are formed between them. The anode-side flow path substrate 40 includes a central portion 40a located at the center in the fuel gas flow direction, and a central portion 40a.
a, the ribs 401... are set higher in the central portion 40a than in the upstream portion 40b and the downstream portion 40c. The high portion 401a of the rib fits into the window 102 to make electrical contact with the anode 23.

Although not shown in FIG. 1, the space between the cathode 22 and the cathode-side flow path substrate 30 and the anode 23
Current collectors 24 and 25 made of water-repellent carbon paper are interposed between the anode and the anode-side flow path substrate 40 (see FIG. 5). The partition plate 50 is an airtight glassy carbon plate having the same size as the anode-side flow path substrate 40, and includes the cathode-side flow path substrate 30 and the anode-side flow path substrate 4.
0, and serves to prevent the air flowing through the cathode side flow paths 311 and the fuel gas flowing through the anode side flow paths 400 from being mixed while electrically conducting the two. I have.

In FIG. 2, 135 to 138 are O
With the ring, the manifold holes 111 to 114 and the slot 12
O-ring groove 131 formed so as to surround 1-124
In the assembled state of the fuel cell, the frame 10
This part is sandwiched between them to seal this part. FIG. 3 is a perspective view showing the overall configuration and operation of the fuel cell 1. Here, the case of operating using hydrogen gas as fuel gas will be described.

As shown in FIG. 1, during operation, the fuel cell 1 is arranged such that the air flow path (cathode side flow path) faces horizontally. Then, from a fan (not shown), the flow path 3
Send air to 01 ... This air is supplied to the cathode side channel 3
Oxygen is supplied to the cathode 22 while flowing through the cells 11 and discharged out of the battery from the channels 302.

On the other hand, hydrogen gas is supplied from the hydrogen gas cylinder 2 to the internal manifold formed by the manifold holes 112, and water is supplied from the water pump 3 to the internal manifold formed by the manifold holes 111. The supplied water and hydrogen gas are distributed to each cell unit 100, and in each cell unit 100, distributed to the upstream portion 40 b of the anode-side flow path substrate 40 from the slot 121 and the slot 122, and 400 flows downstream to supply hydrogen gas to the anode 23 and keep the solid polymer film 21 moist.

The output of the water pump 3 is supplied to the water supply slot 12.
The water pressure at 1 is measured and adjusted so that this value becomes a predetermined water pressure value. The supply pressure of the hydrogen gas is adjusted by the regulator 5. This pressure is usually 100,000 to 100,000 mmH
₂ O, especially about 100 to 800 mmH ₂ O, is suitable.
On the other hand, the pressure of the unreacted hydrogen discharged is adjusted by the regulator 6. This discharge pressure is preferably adjusted so that the fuel utilization rate in the fuel cell 1 is 90% or more.

The unreacted hydrogen gas that has passed through the anode side flow paths 400 is discharged from the battery through the slot 123 through the manifold hole 113, and the water that has passed through the anode side flow path 400 is drawn into the slot 124. From the battery through the manifold hole 114. Thus, the fuel gas is discharged in a state separated from the liquid water. Therefore, the discharged gas can be collected and reused without passing through the separation tank 4.

The water discharged from the fuel cell 1 and the water condensed with the water vapor contained in the exhaust gas are collected in the separation tank 4. The recovered water is cooled by the cooler 7 and supplied again from the water pump 3 to the fuel cell 1. [Detailed configuration and effect from upstream to downstream of anode-side flow path] Returning to FIG. 1, in the upstream, the water distribution board 11 is provided with the water supply slot 121 and the fuel gas supply slot. The gas distribution substrate 12 has an O-ring (not shown) at 122.
It is fitted through.

The water distribution substrate 11 and the gas distribution substrate 12
Are pores 11a and pores 12a in a long thin plate.
Are arranged in contact with the upstream portion 40b of the anode-side flow path substrate 40, and the pores 11a and 12a are opened corresponding to all the anode-side flow paths 400. Specific examples of the water dispersion substrate 11 and the gas distribution substrate 12 include a thin plate made of metal (stainless steel such as SUS304 and SUS316, Ti steel) and a ceramic plate (AL ₂ O).
₃ ), etc., which have pores opened by etching, or plastic (polyester, ABS, perphenyl oxide, PPE, PPS, etc.) with pores opened. it can.

Each of the pores 11a and 12a has the same shape (for example, a circle, an ellipse, and a polygon), the same size, and the same number (for example, one for each flow channel and two for each flow channel). Or three by three.) The thickness of the water distribution substrate 11 and the pore diameter of the pores 11 a
It is desirable to set such that an appropriate resistance (pressure loss) is generated when water passes through a. In practice, the thickness of the substrate is 120 μm to 5 mm, and the diameter of the pores 11 a is 20 μm to 20 μm.
It is desirable to set within the range of 3 mm.

On the surface of the frame 10, the bottom surface 400a of the flow path 400 on the upstream side of the slot 123 which is a gas discharge path.
The water-repellent regions 13 having a larger contact angle of water than the material forming the anode-side flow path substrate 40, that is, the substrate wall surfaces of the anode-side flow paths 400, It is formed to correspond (FIG. 4,
(See FIG. 5). This makes the flow of gas smooth as described later.

The water-repellent region 13 may not necessarily have a water contact angle larger than the substrate wall surface of the anode-side flow paths 400. In other words, even if the contact angles are originally the same, the contact angle does not decrease so much when water is repeatedly contacted during the operation of the battery, and any difference may be generated between the contact angle and the water contact angle of the anode-side flow path substrate 40. . This is because, when water is repeatedly contacted during the operation of the fuel cell, the contact angle (wetability) of the water on the anode-side substrate 40, which is a porous carbon material, is considered to gradually decrease (increase) and stabilize. This is because a separate flow of a gas layer and a liquid layer, which will be described later, can be generated in a region where the contact angle of water sometimes differs.

The water-repellent region 13 is formed in a layer by laying a resin sheet, which is a water-repellent member, on the wall surface of the frame 10 or by coating the resin itself. The frame 10 itself can be made of a water-repellent material. Examples of the water-repellent resin include polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkylvinyl copolymer (PFA), silicone (silicone), polyphenylene sulfide (PPS), and tetrafluoroethylene / hexafluoropropylene. Polymer (FEP) and the like can be mentioned.

On the surface of the frame 10, immediately upstream of the above-mentioned slot 124, the bottom surface 4 of the anode-side channels 400.
00a ... are located at the anode side flow paths 400 ...
A hydrophilic region 14 having a smaller water contact angle than the substrate wall surface is formed (see FIGS. 4 and 5). This hydrophilic area 14
Originally, even if the contact angle of water was not smaller than the substrate wall surface of the anode-side flow paths 400, and was originally the same, the contact angle was reduced when water was repeatedly contacted during battery operation, What is necessary is just to produce a difference between the contact angle of water and the anode-side flow path substrate 40. This is thought to be due to the fact that the water comes into contact repeatedly during the operation of the fuel cell, so that the contact angle (wettability) of the water gradually decreases (increases). Therefore, at this time, a liquid layer described later can be attracted in a region where a difference occurs between the contact angle of water and the anode-side flow path substrate 40.

The hydrophilic region 14 is formed by laying a resin sheet, which is a hydrophilic member, on the wall surface of the frame 10 or by applying a resin in a layer. The higher the hydrophilicity of this region, the better, and it is preferable that the region is made of a water-absorbing material. Specific materials include polyester, rayon, nylon,
Woven and non-woven fabrics mainly composed of polyester / rayon, polyester / acrylic, rayon / polychloral, etc.
Felt can be mentioned.

The "extended flow path" described in the claims refers to the downstream portion 40c of the anode-side flow path.
In the position corresponding to the bottom surface of the extended flow path, a member having a contact angle of water on the surface equal to or larger than the contact angle of water on the inner wall of the plate of the extended flow path is disposed,
Refers to the frame body 10 provided with the water repellent region 13, "at a position corresponding to the bottom surface of the extension flow path, the contact angle of water on the surface is equal to or smaller than the contact angle of water on the inner wall of the plate of the extension flow path. The member in the phrase “a member is disposed” refers to the frame body 10 having the hydrophilic region 14.

FIG. 4 is a cross-sectional view of the fuel cell 1 taken along the water supply channel, and schematically shows the generation, flow, and discharge of the gas-liquid mixture in the flow channel. FIG.
5A and 5B show the operation of the fuel cell 1, FIG. 5A is a diagram schematically showing the upper surface of the cell unit 100, and FIG. It is a figure which shows the -A 'cross section typically.

Water is supplied from the fine pores 11a and fuel gas is supplied from the fine pores 12a to the respective anode-side flow paths 400 to generate a gas-liquid mixture. The gas-liquid mixture flows through each of the anode-side flow paths 400 to supply fuel gas to the anodes and keep the solid polymer membrane moist, and also function as a refrigerant for cooling the battery. The anode-side flow path substrate 40 is formed of a porous carbon material, whereas the current collector 25 disposed on the anode 23 is subjected to a water-repellent treatment. The contact angle of water on the surface is smaller than the contact angle of water on the surface of the current collector 25. Further, also on the downstream side of the position facing the electrode, the contact angle of water with respect to the surface of the anode-side flow path substrate 40 is smaller than the contact angle of water in the water-repellent region 13 as described above.

Accordingly, when the gas-liquid mixture generated in the upstream portion 40b of the anode-side flow paths 400 passes through the portion corresponding to the cell, the liquid layer and the gas layer tend to be separated. . That is, the water is attracted to the substrate 40 side, and a liquid layer mainly composed of water exists on the anode-side flow path substrate 40 side, and mainly the fuel gas and the water vapor are formed on the anode 23 (current collector 25) side. Since the gas flows in a state in which the gas layer composed of is present, the fuel gas is efficiently supplied to the anode 23.

Next, the separated state is similarly maintained downstream from the portion corresponding to the cell. Therefore, the water on the liquid side does not come into contact with the slot 123, and the gas layer comes into contact, so that the gas can be selectively discharged from the slot 123 efficiently. The emission of this gas is
The greater the difference in the contact angle of water between the water-repellent region 13 and the anode-side substrate 40, the higher the efficiency is. Also, the wall surface 1 forming the slot 123
It is preferable to coat 23a with a water-repellent material because water hardly penetrates here. However, if the frame body 10 itself is made of a water-repellent material, there is no need for such a case.

On the other hand, the water passes just below the gas outlet (slot 123) and flows further downstream. At this time, not only the anode-side flow path downstream portion 40c but also the hydrophilic region 14 has high affinity for water (because the anode-side flow path substrate 4
0 is made of a porous carbon material. ), The water contacts the hydrophilic region 14 and covers the entire flow path space, and the downstream portion 40c is sealed with water. As described above, in the fuel cell 1, by covering the entire outlet of the anode-side flow path to the water discharge port with a solid substance such as a water absorbing material as in the above-described conventional technique, the inflow of gas into the water discharge port is prevented. Instead of preventing this, the outlet side achieves this by forcibly sealing off the outlet communicating with the water discharge port (slot 124).

By sealing the anode-side flow path 400 at the lower end in this manner, the gas is uniformly distributed and unreacted gas is prevented from flowing out from the water discharge port.
The discharge of the unreacted gas from the slot 123 can be promoted. If the hydrophilic region 14 is provided as described above,
The dust generated when the material of the flow path substrate is peeled off, or the dust originally existing in water or gas covers the hydrophilic region 14,
It is possible to prevent the water absorption in this region from being lowered. This is because the hydrophilic region 14 is provided so that the anode-side flow paths 400 communicate with the slots 124 at the terminal end (outlet side) and the terminal end is opened as described above.

Since the anode-side flow path is arranged to run in the vertical direction as described above, the water accumulated while sealing the anode-side flow path 400.
It falls to a water discharge port (slot 124) by its own weight. Therefore, there is a very low possibility that the water will rise to the upstream side and enter the slot 123 which is the gas outlet. Furthermore, if the wall surface 123a of the gas outlet 123 is covered with the water-repellent material as described above, even if the water rises to the upstream side, the water infiltrates through the wall surface 123a into the slot 123, It does not stay at the opening. Therefore, in such a sense, it is preferable that the wall surface 123a on which the slot 123 is formed is covered with a water-repellent material.

In the above description, the porous carbon material is used for the anode-side flow path substrate 40 and the surface thereof is not treated at all. For example, the inner wall surfaces of the anode-side flow paths 400 are formed with the hydrophilic regions 14. If the same material is laid or applied, the contact angle of water on the channel wall can be smaller than that of the porous carbon itself,
Since the separation efficiency between the gas layer and the liquid layer is improved, the gas can be selectively discharged more efficiently. The method of increasing the hydrophilicity of the substrate surface by performing such treatment is as follows.
This is particularly effective when a substrate produced by molding using a mixture of carbon such as expanded graphite, graphite, and fornes black and a resin such as phenol is used. This is because a substrate formed by molding generally has low hydrophilicity (the contact angle of water is larger than that of porous carbon).

The contact angle of water can also be reduced by increasing the surface roughness of the anode-side flow path 400... As a method of increasing the surface roughness,
There is a method of polishing the surface of a porous carbon body with sandpaper or forming a fine groove on the bottom of the flow path (application number P
CT / JP98 / 01707). In addition,
In the above description, the so-called internal humidification in which water and the fuel gas are supplied into the fuel cell to generate a gas-liquid mixture in the fuel cell has been described, but before the fuel gas is supplied to the fuel cell body, a steam generator is used. In the case of employing external humidification, the above-described techniques of selective permeation of gas and discharge of water can be applied. However, adapting to internal humidification is more effective because of the large amount of water. Although the case where only the anode side is humidified has been described, the technique of selectively permeating the gas and discharging water as described above also applies to the case where the oxidizing gas supplied to the cathode is humidified and supplied. Can be applied.

Example A fuel cell having the above-described structure was manufactured under the following conditions. The anode-side flow path substrate 40 was formed of a carbon porous material having a contact angle of water of 10 degrees, and a current collector having a contact angle of 140 degrees of water was disposed at a portion corresponding to the anode. Thus, when the gas-liquid mixture flows through the flow path corresponding to the anode, the separated flow forms a gas layer on the anode side and a liquid layer on the bottom side of the flow path.

The gas-liquid mixture that has passed through the area corresponding to the anode flows into the downstream portion 40c of the anode-side flow path substrate. The water-repellent region 13 was formed by attaching a PTFE (polytetrafluoroethylene) tape to a frame. This P
The contact angle of water on the surface of the TFE tape is 90 degrees, which is larger than that of the anode-side flow path. Accordingly, the gas-liquid mixture flowing in the area corresponding to the water repellent area 13 is separated into a hydrophilic area 14 serving as a separated flow forming a gas layer on the water repellent area 13 side and a liquid layer on the channel bottom side.
Was made of a water-absorbing substrate made of a nonwoven nylon nonwoven fabric having a water contact angle of 0 degree. Therefore, since the contact angle of water is smaller than that of the anode-side flow path, the water flowing in the area corresponding to the hydrophilic area 14 is drawn into the hydrophilic area 14 and covers the entire outlet of the flow path.

As described above, the end of the anode-side flow path is water-sealed, so that the gas can be efficiently discharged from the slot 123 and the gas can be uniformly distributed to the cells as described above. Here, the contact angle of water is obtained by measuring the angle Θ between the water droplet shown in FIG. 6 and the surface of the measurement object by the following method.

Measuring device: Contact angle meter CA-D manufactured by Kyowa Interface Science Co., Ltd. Temperature condition: Both water and the object to be measured are at room temperature. Object to be measured: Dry state at room temperature. Measurement time: Measured 30 seconds after dropping. Next, a fuel cell was manufactured under the following conditions, and the cell characteristics were examined.

Electrode area: 100 cm ² Solid polymer membrane: Perfluorocarbon sulfonic acid membrane Anode: Pt-Ru supported carbon Cathode: Pt supported carbon Cell stacking number: 60 [Comparative example] Conventional structure described above ( This is a fuel cell having the configuration shown in FIG. 8), and the manufacturing conditions are the same as those in the above embodiment.

[Experiment] When the fuel cell of the example and the fuel cell of the comparative example were operated under the following conditions, cell cells were measured with time, and their performances were compared and examined.・ Current density: 0.4 A / cm ²・ Fuel gas utilization rate: 70% ・ Oxidant utilization rate: 20% ・ Fuel gas: Reformed gas obtained by steam reforming methane (H ₂ : 38.3%, N ₂₎ : 43%, CO ₂ : 17%, C
H _4: 0.7%) · oxidants: showed air results in FIG.

As is apparent from FIG. 7, in the battery of the comparative example, the cell voltage decreased over time,
Stable operation was possible only for about 0 minutes. On the other hand, in the battery of the example, stable power generation was possible for a long time. It should be noted that, even in the fuel cell having the configuration shown in FIG. 9 which selectively permeates the gas, if the continuous operation is performed for about 100 minutes, stable characteristics can be obtained. Since the water-absorbing substrate is clogged with dust and the water-absorbing performance is reduced, the characteristics are reduced. The fuel cell of the embodiment is excellent in that there is no such a thing.

[0053]

As described above, according to the polymer electrolyte fuel cell of the present invention, the first plate (anode-side flow path substrate) is located downstream of the end of the anode in the fuel gas flow direction. An extended flow path extending from the anode-side flow path, and at a position corresponding to the bottom surface of the extended flow path, the contact angle of water on the surface is in contact with water on the inner wall of the plate of the extended flow path. A member equivalent to or larger than the corner is arranged, and a gas outlet is opened on the downstream side of the member, and further, on the downstream side of the gas outlet, at a position corresponding to the bottom surface of the extension flow path. A member whose surface contact angle is equal to or smaller than the contact angle of water on the inner wall of the plate of the extension flow path is provided, and a water outlet communicating with the extension flow path is opened downstream of the member. So that gas can be discharged efficiently while draining efficiently. .

[0054] "Further, if applied similar techniques to the second plate (cathode-side channel substrate), while also effectively discharge the gas at the cathode side, waste water can be performed efficiently. This Is particularly effective when humidifying an oxidizing gas.

[Brief description of the drawings]

FIG. 1 is an assembly diagram showing a configuration of a cell unit as a basic component of a polymer electrolyte fuel cell according to an embodiment.

FIG. 2 is a schematic view after assembling the cell unit.

FIG. 3 is a perspective view showing the overall configuration and operation of the polymer electrolyte fuel cell.

FIG. 4 is a sectional view of a main part of the polymer electrolyte fuel cell.

5A and 5B show an operation of the polymer electrolyte fuel cell. FIG. 5A is a diagram schematically showing an upper surface of a cell unit, and FIG. It is a figure which shows a cross section typically.

FIG. 6 is a schematic diagram showing a definition of a contact angle of water.

FIG. 7 is a characteristic diagram of a battery showing experimental results.

FIG. 8 is a diagram showing a configuration of a conventional polymer electrolyte fuel cell.

FIG. 9 is a diagram showing a configuration of another conventional polymer electrolyte fuel cell.

[Explanation of symbols]

 Reference Signs List 1 solid polymer fuel cell 10 frame 11 water dispersion substrate 11a pore 12 gas distribution substrate 12a pore 13 water-repellent region 14 hydrophilic region 20 cell 21 solid polymer film 22 cathode 23 anode 24, 25 current collector 30 cathode Side flow path substrate 40 Anode side flow path substrate 40a Central part (anode side substrate) 40b Upstream part (anode side substrate) 40c Downstream part (anode side substrate) 50 Partition plate 61, 62 gasket 71, 72 end plate 100 Cell unit 101 Notch 102 Window 103 Recess 111 Manifold hole (for water supply) 112 Manifold hole (for gas supply) 113 Manifold hole (for gas discharge) 114 Manifold hole (for water discharge) 121, 122, 123, 124 groove hole 123a groove hole Forming wall surface 131, 132, 133, 134 O-ring groove 135 136, 137, 138 O-ring 300 Frame 301 Flow path (cathode side) 302 Flow path (cathode side) 303 Window 310 Flow path substrate body 311 Flow path (cathode side) 400 Anode side flow path 400a Anode side flow path bottom 401 rib

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yo Hamada 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Inside Sanyo Electric Co., Ltd. No. 5 Sanyo Electric Co., Ltd. (72) Inventor Koji Nishio 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-9-283153 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) H01M 8/00-8/24

Claims (5)

(57) [Claims] 1. A cell comprising a solid polymer membrane provided with a cathode and an anode, a first plate having an anode side channel formed opposite the anode, and a cathode side channel formed opposite the cathode. A polymer electrolyte fuel cell sandwiched between the formed second plate and generating electricity by supplying fuel gas and water to the anode side flow path and supplying oxidant gas to the cathode side flow path Wherein the first plate has an extension passage extending from the anode-side passage downstream of the end of the anode in the fuel gas flow direction, and a bottom surface of the extension passage. At the corresponding position, a member whose surface contact angle with water is equal to or greater than the contact angle of water on the inner wall of the plate of the extension flow path is arranged, and a gas outlet is opened downstream of the member. Further, on the downstream side of the gas outlet, And, at a position corresponding to the bottom surface of the extension flow path, a member having a contact angle of water on the surface equal to or smaller than a contact angle of water on the inner wall of the plate of the extension flow path is disposed, and on the downstream side of the member. A solid polymer fuel cell, wherein a water outlet communicating with the extension flow path is provided. 2. A cell in which a cathode and an anode are arranged on a solid polymer membrane, a first plate having an anode-side channel formed opposite to the anode, and a cathode-side channel formed opposite the cathode. A polymer electrolyte fuel cell sandwiched between the formed second plate and generating electricity by supplying fuel gas and water to the anode side flow path and supplying oxidant gas to the cathode side flow path Wherein the second plate has an extended flow path extending from the cathode-side flow path downstream of an end of the cathode in the oxidant gas flow direction, and a bottom surface of the extended flow path In a position corresponding to the above, a member whose surface contact angle of water is equal to or greater than the contact angle of water on the inner wall of the plate of the extension flow path is arranged, and a gas outlet is opened on the downstream side of the member. And further downstream of the gas outlet. In the position corresponding to the bottom surface of the extension flow path, a member whose surface contact angle is equal to or smaller than the contact angle of water on the inner wall of the plate of the extension flow path is disposed, and on the downstream side of the member. Is a polymer electrolyte fuel cell characterized in that a water outlet communicating with the extension flow path is opened. 3. The second plate has an extension passage extending from the cathode-side passage downstream of an end of the cathode in the oxidant gas flow direction, and At a position corresponding to the bottom surface, a member whose surface contact angle with water is equal to or greater than the contact angle of water with the inner wall of the plate of the extension flow path is arranged, and a gas outlet is opened downstream of the member. Further, on the downstream side of the gas discharge port, at a position corresponding to the bottom surface of the extension passage, the contact angle of water on the surface is equal to or smaller than the contact angle of water on the plate inner wall of the extension passage. 2. The polymer electrolyte fuel cell according to claim 1, wherein a member is disposed, and a water outlet communicating with the extension flow path is opened downstream of the member. 4. A member, which is disposed corresponding to the bottom surface of the extending flow path and has a contact angle of water on the surface equal to or larger than a contact angle of water on the inner wall of the plate of the extending flow path, is a water-repellent material. The polymer electrolyte fuel cell according to any one of claims 1 to 3, wherein: 5. A member provided with a contact angle of water on the surface thereof, which is equal to or smaller than a contact angle of water on the inner wall of the plate of the extension flow path, which is arranged corresponding to the bottom surface of the extension flow path, is a water-absorbing material. The polymer electrolyte fuel cell according to any one of claims 1 to 4, wherein: