JP3461149B2 - Polymer electrolyte fuel cell - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer electrolyte fuel cell, and more particularly to a polymer electrolyte fuel cell for generating electricity while supplying fuel gas and water to a channel on the anode side.

[0002]

2. Description of the Related Art A fuel cell has a cell in which a cathode and an anode are arranged on two main surfaces of an electrolyte membrane which are opposed to each other, and an oxygen-containing oxidant gas and a fuel gas containing hydrogen are respectively contained in the cathode and the cathode. And are supplied respectively to generate electricity. In many of the fuel cells that have been put into practical use, the above-mentioned cell is used as an anode-side channel substrate in which a gas channel for fuel gas flow is formed and a cathode-side channel substrate in which a gas channel for oxidant gas flow is formed. It has a structure in which a basic unit is formed by sandwiching the basic unit and a plurality of basic units.

In the polymer electrolyte fuel cell, a polymer electrolyte membrane is used as the electrolyte membrane. This solid polymer membrane needs to be in a wet state during operation in order to secure ionic conductivity. As one of the methods for making the solid polymer membrane wet in this way, a method of supplying fuel gas and water to the gas channel on the anode side has been studied. In this method, water supplied to the gas channel on the anode side has an effect of wetting the solid polymer membrane and at the same time cooling the battery, so that excellent battery characteristics can be obtained.

Such a conventional fuel cell will be described with reference to FIG. The figure is an assembly drawing of a cell unit 100 that constitutes a fuel cell. The cell unit 100 includes a cell 20 in which a cathode 22 and an anode 23 are arranged on two main surfaces of a solid polymer film 21 that face each other on one surface side (the upper surface side in FIG. 7) of a rectangular frame body 10, A plurality of cathodes, which are formed in parallel with each other, are fitted in the cathode-side channel substrate 30 having a plurality of cathode-side channels 311 formed in parallel with each other, and are formed in parallel with each other on the other surface side (lower surface side in FIG. 7) of the frame body 10. The anode side flow channel substrate 40 having the side channel 400 and the partition plate 50 are fitted and configured.
Incidentally, in the figure, since the anode 23 is on the back surface of the solid polymer film 21, it is indicated by a broken line.

The cell 20 is held in a state of being sandwiched between the cathode side flow channel substrate 30 and the anode side flow channel substrate 40, and the fuel is stored in the anode side channel 400 in the direction indicated by the white arrow in the figure. Gas is supplied, and the oxidant gas is supplied to the cathode side channel 311 in the direction indicated by the thick arrow in the figure.

A notch 101 for fitting the cell 20 and the cathode side flow channel substrate 30 is formed in the center of the frame 10 on one side (the upper side in FIG. 7) in the fuel gas flow direction. . Further, on the other surface side (lower surface side in FIG. 7) of the frame body 10, a recess 103 into which the anode side flow channel substrate 40 and the partition plate 50 are fitted is formed. Further, the notch 1
A window 102 is opened in the center of 01 so that the anode side flow channel substrate 40 and the anode 23 can come into contact with each other.

The anode side flow channel substrate 40 has a central portion 40a located at the center in the fuel gas flow direction and the central portion 40.
It is composed of an upstream portion 40b and a downstream portion 40c extending from a, and the height of the rib 401 is set higher in the central portion 40a than in the upstream portion 40b and the downstream portion 40c. And
The tops 401a of the ribs 401 are fitted into the windows 102 and are in electrical contact with the anode 23.

A pair of manifold holes 111 for supplying water and a groove hole 121, and a pair of manifold holes 112 for supplying a fuel gas and a groove hole are provided upstream of the frame body 10 in the fuel gas flow direction. 122 has been opened. Furthermore, a pair of manifold holes 113 and a groove hole 123 for discharging unreacted fuel gas and a pair of a manifold hole 114 and a groove hole 124 for discharging water are provided in the downstream portion of the frame body 10. There is.

Each groove hole 121 to 124 is formed in a direction orthogonal to the anode side channel, and both ends thereof communicate with each manifold hole 111 to 114 via an elliptical surface groove (not shown). ing.

The water distribution substrate 11 is fitted in the water supply groove 121, and the gas distribution substrate 12 is fitted in the raw material gas supply groove 122 via O-rings (not shown). . These water distribution substrate 11 and gas distribution substrate 12
Both are small holes 11a and small holes 1 on a long thin plate, respectively.
2a has been opened, and the anode side channel substrate 4
It is installed in contact with the upstream portion 40b of 0.

Further, a gas permeable substrate 13 for selectively discharging the gas is fitted into a groove hole 123 provided on the downstream side for discharging the unreacted reaction gas, and a groove for discharging the water. The water absorbing base material 14 is fitted into the hole 124.

The cathode side channel substrate 30 is constructed by fitting the cathode side channel substrate 310 into the frame 300. In this frame 300, a window 303 is opened in the center of a rectangular flat plate, and an introduction channel 301 for introducing air into the channel 311 is provided on the surface opposite to the cathode 22 (upper surface side in FIG. 7). And a lead-out channel 302 for leading out the oxidant gas from the channel 311.

A gasket 61 is interposed between the cell 20 and the cathode side flow path substrate 30, and the cell 20 and the notch 1
Gasket 62 is interposed between 01 and 01.

Further, between the cathode 22 and the cathode side channel substrate 30, and between the anode 23 and the anode side channel substrate 40.
A current collector made of water-repellent carbon paper is interposed between and.

The partition plate 50 is an airtight glassy carbon plate having the same size as the anode side flow channel substrate 40, and is disposed between the cathode side flow channel substrate 30 and the anode side flow channel substrate 40. In this case, the air flowing through the cathode side channel 311 and the fuel gas flowing through the anode side channel 400 are prevented from being mixed with each other while electrically conducting the two.

In the fuel cell having the above structure, the oxidizing gas is fed into the introduction channel 301 on the cathode side. The oxidant gas supplies oxygen to the cathode 22 while flowing through the cathode side channel 311, and is discharged from the outlet channel 302 to the outside of the battery.

On the other hand, fuel gas is supplied to the groove hole 122 communicating with the manifold hole 112, and the manifold hole 11
Water is supplied to the slot 121 communicating with 1. The supplied water and fuel gas are fitted into the water supply groove 121, respectively, and the water distribution substrate 11 and the fuel gas supply groove 12 are fitted therein.
Small holes 11 drilled in the gas distribution substrate 12 fitted in
It is supplied to the upstream portion 40b of the anode side flow channel substrate 40 through a and 12a. Then, these fuel gas and water flow downstream in the anode-side channel 400, and the anode 2
3 is supplied with hydrogen gas and the solid polymer film 21 is humidified.

FIG. 8 is a schematic plan view for explaining the flow of fuel gas and water supplied to the anode side flow channel substrate 40. Referring to the figure, a small hole 12 for introducing fuel gas
a is provided for all the anode-side channels 400, and every other small hole 11a for water supply is provided. The positions of the small holes 11a and 12a are set so that the water supplied from the small holes 11a for supplying water flows near the small holes 12a for supplying fuel gas. still,
Small holes 11a for supplying water may be provided for all the anode-side channels 400.

FIG. 9 is a perspective view showing the overall structure of the polymer electrolyte fuel cell 1. Here, the case where hydrogen gas is used as the fuel gas will be described.

In the polymer electrolyte fuel cell 1, a large number of cell units 100 are stacked, and both ends thereof are a pair of end plates 71,
It is sandwiched by 72. Such a fuel cell 1
As shown in the same figure, is arranged such that the flow passage (cathode side channel) of the oxidant gas is horizontally oriented during operation. Then, air as an oxidant gas is sent to the introduction channel 301 by a fan (not shown). This air supplies oxygen to the cathode 22 while flowing through the cathode side channel 311, and is discharged to the outside of the cell from the outlet channel 302.

On the other hand, hydrogen gas is supplied from a hydrogen gas cylinder to the internal manifold formed of the manifold holes 112, and water is supplied from the water pump 3 to the internal manifold formed of the manifold holes 111.

The supplied water and hydrogen gas are distributed to each cell unit 100, and in each cell unit 100, are distributed from the groove holes 121 and 122 to the upstream portion 40b of the anode-side flow channel substrate 40, so that the anode Flowing through the side channels 400 ... Downstream, hydrogen gas is supplied to the anode 23 and the solid polymer film 21 is humidified.

The output of the water pump 3 is the slot 12 for water supply.
The water pressure at 1 is measured and adjusted so that this value becomes a predetermined water pressure value.

The unreacted hydrogen gas that has passed through the anode-side channel 400 is discharged from the battery through the groove hole 123 and the manifold hole 113 to the anode-side channel 400.
Water that has passed through the
Is discharged through the battery to the outside of the battery.

The water discharged from the fuel cell 1 and the water condensed from the water vapor contained in the exhaust gas are collected in the separation tank 4. Then, the recovered water is cooled by the cooler 7 and is again supplied from the water pump 3 to the fuel cell 1.

[0026]

As described above, the small holes 11a for supplying water and the small holes 12a for supplying fuel gas are the same as the water supplied from the small holes 11a for supplying water. The position is set so as to flow near the small hole 12a. However, since the water supplied from the small holes 11a for supplying water moves to the downstream side along the surface of the frame body 10 facing the anode-side flow channel substrate 40, the traveling direction changes in the middle thereof, and the fuel gas The small hole 12a for supply may be closed. Since the clogging of the small holes 12a suppresses the supply of the fuel gas, the distribution of the fuel gas becomes non-uniform, and there is a problem that the cell performance varies and the cell performance deteriorates with time.

The present invention has been made in view of the above conventional problems, and provides a polymer electrolyte fuel cell which reduces variations in cell performance within a module and has little deterioration in cell performance over time. It is intended to be provided.

[0028]

In order to solve the above conventional problems. The polymer electrolyte fuel cell of the present invention comprises a cell having a cathode and an anode on two main surfaces of a polymer electrolyte membrane facing each other, and an anode-side channel formed by a plurality of ribs arranged in parallel with each other. And a second plate having a cathode side channel formed by a plurality of ribs arranged in parallel with each other, and the anode side channel and the cathode side channel face each of the anode and the cathode. like,
While sandwiching the cell between the first plate and the second plate, the first plate has an extending portion in which the plurality of ribs extend upstream of the anode-side channel, Further, in the extending portion, the fuel gas supply is in contact with the tops of the plurality of ribs forming the anode side channel and has a plurality of gas supply small holes for distributing and supplying the fuel gas to each anode side channel. Polymer fuel cell having a gas-liquid supply plate, and a water supply section having a plurality of water supply small holes for distributing water to each anode side channel upstream of the fuel gas supply section And the anode of the gas-liquid supply plate
It is provided on the surface facing the side channel and supplies the raw material gas.
It is characterized in that it has a water guiding means consisting of a convex portion between the small hole for water supply and the small hole for water supply .

Here, the convex portion is for supplying the raw material gas.
Equipped with an extension that bypasses the small hole and extends to the downstream side of the small hole.
It is characterized by getting .

[0030] The protrusion certain stomach is, you characterized in that provided in contact with the side surface of the rib.

Alternatively, the convex portion includes the plurality of ribs.
It is characterized by being crossed across .

Then, the convex portion is the gas-liquid supply plate.
It is characterized in that it is a protrusion of the g .

Alternatively , the convex portion is the gas-liquid supply plate.
Affixed to the surface of the
It is characterized by comprising a water repellent member .

[0034]

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) With respect to a polymer electrolyte fuel cell according to a first embodiment of the present invention,
This will be described with reference to FIG. The figure is a conceptual explanatory view for explaining the main part of the polymer electrolyte fuel cell according to the present embodiment, and FIG. 3A is a conceptual sectional view of a water and fuel gas supply section. Further, FIG. 3B is a conceptual plan view.

Referring to FIG. 1, the fuel cell according to the present embodiment is different from the conventional one in that it is a surface of the frame body 10 facing the anode side flow channel substrate 40, and has a small hole 12 for fuel gas supply.
The point is that a convex portion 501 is provided upstream of a. The same figure (b)
As shown in, the convex portion 501 is provided wider than the small hole 12a for supplying the fuel gas. Therefore, according to the present embodiment, the flow of water supplied from the small hole 11a for water supply is blocked by the convex portion 501, bypasses the small hole 12a for fuel gas supply, and flows downstream. Therefore, it is possible to reduce the water clogging of the small holes 12a for supplying the fuel gas as compared with the conventional case.

The shape of the convex portion 501 is not limited to the shape shown in FIG. Various shapes of the convex portion 501 are shown in the conceptual plan view of FIG. For example, as shown in FIG. 3A, an extension portion 50 that bypasses the small holes 12a for fuel gas supply on both sides and extends to the downstream side of the small holes 12a.
It may have 1a. With such a configuration, it is possible to more reliably suppress water clogging of the small holes 12a for supplying fuel gas.

Further, as shown in FIG. 6B, it may be provided in an oblique direction and the lower end thereof is located downstream of the small hole 12a for supplying fuel gas.

Alternatively, as shown in FIG. 7C, both ends thereof may be in contact with the side surface of the rib 401. According to such a configuration, the flow of water supplied from the small hole 11a for supplying water is completely blocked by the convex portion 501, is guided to the rib 401, and is guided downstream through the side surface thereof. It is possible to suppress water clogging of the small holes 12a for supplying the fuel gas.

Further, as shown in FIG. 3D, a plurality of ribs 401 may be provided across the ribs 401. Even with such a configuration, the flow of water is completely blocked by the convex portion 501, and the water will flow to the downstream side via the side surface and the top of the rib 401.

In addition, according to the present invention, the convex portion 501 is formed.
Is not limited to the above-described shape, as long as it supplies the water supplied from the small hole 11a for supplying water to the downstream side by bypassing the small hole 12a for supplying fuel gas.

Further, as the convex portion 501, for example, by using a mold at the time of manufacturing the frame plate 10, the frame plate 10 can be manufactured.
It is possible to use a protrusion that is integrally formed with. According to such a configuration, since the convex portion 501 can be manufactured at the same time when the frame plate 10 is manufactured, the manufacturing cost can be reduced.

Alternatively, the anode side channel substrate 4 of the frame plate 10
A water-repellent member is attached to the surface facing 0, and the projection 501 is formed.
Can also be As such a water repellent member, for example, a Teflon tape or a Teflon sheet may be used.
Even with such a configuration, the same effect can be obtained.

(Second Embodiment) A polymer electrolyte fuel cell according to a second embodiment of the present invention will be described with reference to FIG. FIG. 1 is a conceptual explanatory view for explaining the main part of the polymer electrolyte fuel cell according to the present embodiment, and FIG. 1A is a conceptual sectional view of a fuel gas and water supply part. Also, FIG. 3B is a conceptual plan view.

Referring to FIG. 3, the present embodiment differs from the first embodiment in that the water supplied from the small hole 11a for supplying water to the anode is provided upstream of the small hole 12a for supplying fuel gas. The point is that a water absorbing member 502 for guiding to the side channel substrate 40 is provided. According to such a configuration, the water supplied from the small holes 11a for supplying water is guided to the bottom surface of the anode-side flow channel substrate 40 via the water absorbing member 502, and flows along the bottom surface to the downstream side. It becomes possible to suppress water clogging of the small holes 12a for gas supply. The water absorbing member 502 is, for example, a woven or non-woven fabric made of fibers based on paper, cotton, carbon, glass, ceramics, etc., or synthetic fibers such as acrylic, nylon, polyester, PET, rayon, polyvinyl alcohol fibers, etc. Alternatively, a porous material or a foam material made of ceramic, carbon, metal, polymer material or the like can be used.

The shape of the water absorbing member 502 is not limited to the shape shown in FIG. Various shapes of the water absorbing member 502 are shown in the conceptual plan view of FIG. For example, as shown in FIG. 7A, the water absorbing member 502 may be provided in the area including the small holes 11a for supplying water. According to such a configuration, water can be guided to the flow path substrate 40 more reliably.

Alternatively, as shown in FIG.
The water absorbing member 502 may be provided so as to contact the side surface of the water absorbing member 502. According to such a configuration, the water supplied from the small holes 11a for supplying water is guided to the side surface of the rib 401 via the water absorbing member 502, and flows along the side surface to the downstream side. It is possible to suppress water clogging of the small holes 12a for supply. In this case, the water absorbing member 502 may be in contact with the flow path substrate 40, but may not be in contact with it.

Further, as shown in FIG. 7C, the water absorbing member 502 is arranged so as to be crossed across a plurality of ribs 401.
May be provided. According to such a configuration, the small 1 for water supply
The water supplied from 1a is guided to the side surface and the top of the rib through the water absorbing member 502, and flows to the downstream side along the side surface and the top, so that the water in the small hole 12a for supplying the fuel gas is supplied. It is possible to suppress clogging.

As described above, in the present invention, the water supplied from the small hole 11a for supplying water is diverted from the small hole 12a for supplying fuel gas to the upstream side of the small hole 12a for supplying fuel gas. And a convex portion or a water absorbing member for guiding it to the downstream side. Therefore, according to the present invention, the water supplied from the water supply small hole 11a bypasses the fuel gas supply small hole 12a and flows to the downstream side. Water clogging is suppressed. As a result, according to the present invention, the fuel gas is substantially evenly distributed to the channels on the anode side, and there is little variation in cell performance, and a polymer electrolyte fuel cell in which deterioration of cell performance over time is suppressed is provided. It becomes possible to do.

(Examples) The cell units according to the first embodiment shown in FIGS. 1 and 2A to 2D were manufactured, and were set as Examples 1 to 5, respectively. 3 and 4 (a) to (c)
The cell unit according to the second embodiment shown in FIG. 2 was manufactured, and these were set as Examples 6 to 9, respectively. The main specifications are as follows. Electrode area: 100 cm ² Solid polymer membrane: Perfluorocarbon sulfonic acid anode: Pt-Ru-supported carbon cathode: Pt-supported carbon (Comparative example) Same as the example except that no convex portion or water absorbing member was provided. A unit cell having the configuration was prepared and used as Comparative Example 1.

(Experiment 1) 5 units of water were supplied from the small holes for water supply of the unit cells of Examples 1 to 9 and the unit cell of Comparative Example 1.
The rate of water clogging of the small holes for fuel gas supply, which occurred when the fuel gas was supplied at a flow rate of 0 ml / min, was visually observed.
In addition, small holes for water supply were provided for all the channels on the anode side, and the experiment was conducted without supplying the fuel gas. As a result, 20% of the small holes in the unit cell of Comparative Example 1 were clogged with water, whereas the unit cells of Examples 1 to 9 had no small holes.

(Experiment 2) Sixteen unit cells of Examples 1 and 6 (unit cells having the structures of FIGS. 1 and 3) were laminated to obtain fuel cells of Examples 10 and 11. Similarly, 16 unit cells of Comparative Example 1 were stacked to form a fuel cell of Comparative Example 2.

Then, Examples 10 and 11 and Comparative Example 2
The fuel cell of No. 1 was operated under the following conditions with the amount of cooling water supplied being 50 ml / min, and the voltage of each cell was measured.

Current density: 0.5 A / cm ² Fuel gas: 80% H ₂ /20% CO ₂ Fuel gas utilization rate: 60% Oxidant gas utilization rate: 15% FIG. 5 shows the results of this experiment. FIG. 11 is a characteristic diagram showing the cell voltage of each cell.

As shown in the figure, in the fuel cell of Comparative Example 2, cells having a lowered voltage were generated. On the other hand, in the fuel cells of Examples 10 and 11, there was almost no variation in cell voltage.

(Experiment 2) Examples 10 and 11 and Comparative Example 2
The fuel cell of was continuously operated under the following conditions, and the average cell voltage was measured.

Current density: 0.5 A / cm ² Fuel gas: 80% H ₂ /20% CO ₂ Fuel gas utilization rate: 60% Oxidant gas utilization rate: 15% Cooling water amount: 20 ml / min per cell Operating time : 50 hr FIG. 6 shows the results of this experiment and is a diagram showing the change over time of the average cell voltage.

The average cell voltage of the fuel cell of the comparative example decreased with time, whereas the average cell voltage of the fuel cell of the example hardly decreased.

This is because, in the fuel cell of the comparative example, the number of channels closed with water in the small holes 12a for supplying fuel gas increases with the passage of time, the channels not supplied with fuel increase, and the cell voltage increases. On the other hand, in the fuel cell of the present embodiment, the water flows around the small holes 12a while bypassing the small holes 12a. Therefore, it is considered that the small holes 12a are not blocked even after a lapse of time.

[0060]

As described above, according to the present invention, the small hole 11a for supplying water is provided upstream of the small hole 12a for supplying fuel gas.
There is provided a convex portion or a water absorbing member for guiding the water supplied from the downstream side by bypassing the fuel gas supplying 12a. Therefore, according to the present invention, the water supplied from the water supply small hole 11a bypasses the fuel gas supply small hole 12a and flows to the downstream side.
The water clogging of 2a is suppressed. As a result, according to the present invention, the fuel gas is substantially evenly distributed to the channels on the anode side, and there is little variation in cell performance, and a polymer electrolyte fuel cell in which deterioration of cell performance over time is suppressed is provided. It becomes possible to do.

[Brief description of drawings]

FIG. 1 is a conceptual explanatory diagram for explaining a main part of a polymer electrolyte fuel cell according to a first embodiment.

FIG. 2 is a conceptual plan view of a convex portion according to the first embodiment.

FIG. 3 is a conceptual explanatory diagram for explaining a main part of a polymer electrolyte fuel cell according to a second embodiment.

FIG. 4 is a conceptual plan view of a convex portion according to a second embodiment.

5 is a characteristic diagram showing the voltage of each unit cell in the fuel cells of Examples 10 and 11 and Comparative Example 2. FIG.

FIG. 6 is a characteristic diagram showing changes with time in average cell voltage in the fuel cells of Examples 10 and 11 and Comparative Example 2.

FIG. 7 is an assembly diagram of a unit cell in a conventional polymer electrolyte fuel cell.

FIG. 8 is a schematic plan view for explaining flows of fuel gas and water in a conventional polymer electrolyte fuel cell.

FIG. 9 is a perspective view showing an overall configuration of a conventional polymer electrolyte fuel cell.

[Explanation of symbols]

10 ... Frame body, 11 ... Water distribution substrate, 11a ... Small hole, 12 ...
Gas distribution substrate, 12a ... Small holes, 21 ... Solid polymer membrane, 2
2 ... Cathode, 23 ... Anode, 40 ... Anode channel substrate, 401 ... Anode channel, 401 ... Rib, 5
01 ... convex portion, 502 ... water absorbing member

Front page continuation (56) References International Publication 98/052242 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 8/02 H01M 8/04 H01M 8/10

Claims (6)

(57) [Claims] 1. A first plate having a cell in which a cathode and an anode are respectively disposed on two main surfaces of a solid polymer membrane facing each other, and an anode-side channel formed by a plurality of ribs arranged in parallel with each other. And a second plate having a cathode-side channel formed by a plurality of ribs arranged in parallel with each other, the cell so that the anode-side channel and the cathode-side channel face the anode and the cathode, respectively. Is sandwiched between the first plate and the second plate, and the first plate has an extension portion in which the plurality of ribs extend upstream of the anode-side channel, and In the extending portion, the fuel gas is distributed to each anode side channel while abutting on the tops of the plurality of ribs forming the anode side channel. A fuel gas supply unit having a plurality of gas supply small holes, and a water supply unit having a plurality of water supply small holes for distributing and supplying water to each anode side channel on the upstream side of the fuel gas supply unit. A polymer electrolyte fuel cell having a gas-liquid supply plate, comprising:
On the surface to be used for supplying the raw material gas and for supplying water
A polymer electrolyte fuel cell characterized in that it has a water-conducting means consisting of a convex portion between the small pores . 2. The convex portion bypasses the small hole for supplying the raw material gas.
The solid polymer fuel cell according to claim 1, further comprising an extending portion that is rotated and extends to the downstream side of the small hole . 3. The protrusion is provided so as to abut a side surface of the rib.
Polymer electrolyte fuel cell according to claim 1, wherein the eclipse was. 4. The protrusion extends across the plurality of ribs.
The polymer electrolyte fuel cell according to claim 1 , wherein the polymer electrolyte fuel cell is horizontally mounted . 5. The protrusion is a protrusion of the gas-liquid supply plate.
Polymer electrolyte fuel cell of any of claims 1乃 Optimum 4 serial <br/> mounting, characterized in that it. Wherein said convex portion, wherein the gas-liquid distributor plate
Water-repellent part attached to the surface facing the anode channel
The polymer electrolyte fuel cell according to any one of claims 1 to 4 , which is made of a material .