JP2003282099A - Polymer electrolyte fuel cell - Google Patents

Abstract

(57) [Summary] (Problem corrected) [PROBLEMS] In a conventional separator shape, gas supply becomes uneven in an electrode surface, and there has been a problem that battery performance is deteriorated and stability cannot be ensured. SOLUTION: Sub-manifolds 18a, 19 having an increased cross-sectional area are provided in a part of a gas passage 17 of a separator 11 plate.
b is formed. As a result, the gas supply is made uniform, the distribution of power generation in the electrode plane is eliminated, and the stability and efficiency of the fuel cell can be improved.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a portable power source,
The present invention relates to a fuel cell using a solid polymer electrolyte used in a power source for electric vehicles, a cogeneration system for home use and the like.

[0002]

2. Description of the Related Art A fuel cell using a solid polymer electrolyte is
The fuel gas containing hydrogen and the oxidant gas containing oxygen such as air are reacted electrochemically to generate electric power and heat at the same time. This fuel cell
Basically, it consists of a polymer electrolyte membrane that selectively transports hydrogen ions, and a pair of electrodes arranged on both sides of the electrolyte membrane. The electrode is composed of a catalyst layer mainly composed of carbon powder carrying a platinum group metal catalyst, and a gas diffusion layer formed on the outer surface of the catalyst layer and having both air permeability and electronic conductivity. In order to prevent the supplied fuel gas and oxidant gas from leaking out and the two types of reaction gas from mixing with each other, a gas sealant or gasket is placed around the electrode with a polymer electrolyte membrane sandwiched between them. It The sealing material and the gasket are integrally assembled with the electrode and the polymer electrolyte membrane in advance. This is called MEA (electrolyte membrane-electrode assembly). A conductive separator plate for mechanically fixing the MEA and electrically connecting adjacent MEAs to each other in series is arranged on the outer side of the MEA. A gas flow path for supplying the reaction gas to the electrode surface and carrying away the generated water and the surplus gas is formed in a portion of the separator plate that is in contact with the MEA. The gas flow path is
Although it can be provided separately from the separator plate, it is general to provide a groove on the surface of the separator plate to form a gas flow path.

In order to supply the fuel gas or the oxidant gas to the gas passage of the separator plate, the pipe for supplying the fuel gas or the oxidant gas is branched according to the number of separator plates to be used, and the branch destination is directly connected. A piping jig connected to the groove of the separator plate is required. This jig is called a manifold, and the type in which the fuel gas or oxidant gas supply pipe is directly connected to the groove is called an external manifold.
There is a type of this manifold called an internal manifold having a simpler structure. The internal manifold is one in which a through hole is provided in a separator plate having a gas flow path, the inlet and outlet of the gas flow path are connected to this hole, and the reaction gas is directly supplied from this hole. These MEAs and separator plates are alternately stacked to form 10 to 200 cells,
The structure of a general laminated battery is that the laminated body is sandwiched between end plates via a current collecting plate and an insulating plate, and both end plates are fastened with fastening rods.

A typical structure of a fuel cell in which a conductive separator plate and an MEA are laminated is shown in FIG. The polymer electrolyte membrane 2 and the MEA 5 composed of the anode 3 and the cathode 4 sandwiching the polymer electrolyte membrane 2 are alternately laminated with the separator plate 1. The anode and the cathode are composed of a catalyst layer in contact with the electrolyte membrane and a gas diffusion layer in contact with the separator plate. The separator plate 1 has a gas channel 6 for supplying and discharging the fuel gas to the anode 3, and a gas channel 7 for supplying and discharging the oxidant gas to the cathode 4.
FIG. 15 is a front view of the separator plate 1 viewed from the cathode side.
Shown in. The region surrounded by the alternate long and short dash line indicated by X in the figure is in contact with the electrode. The separator plate 1 is provided with an inlet side manifold hole 8a for the oxidizing gas, an outlet side manifold hole 8b, an inlet side manifold hole 9a for the fuel gas, and an outlet side manifold hole 9b. Oxidant gas flow path 7
Are formed by four parallel grooves connecting the manifold holes 8a and 8b.

In the fuel cell having such a structure, all the reaction gas during power generation does not flow through the gas passage formed on the surface of the separator plate, but the gas diffusion layer of the porous body located at the outermost portion of the MEA. Gas also flows inside. This flow is called underflow. In order to maintain stable and high battery performance, it is important to make the balance of gas flow and underflow in the gas flow path uniform over the entire electrode area. The flow direction of this underflow depends on the porosity and thickness of the gas diffusion layer and the gas pressure flowing through it. Therefore, due to these variations, there were portions where the gas supply was rich and portions where the gas supply was insufficient within the electrode surface.
Therefore, there is a problem that a portion where the amount of power generation differs is generated in the electrode surface, and the current density increases in the portion where the power generation concentrates, so that the battery voltage decreases. Further, when the reaction gas is supplied to the battery in a highly humidified state, there is a problem that condensed water or generated water is accumulated in the gas flow passage where the gas supply is not so large, which causes more power generation amount distribution.

These problems are particularly remarkable when the gas passage 7 has a meandering shape as shown in FIG. Further, in the hatched area indicated by Y in FIG. 15, there is a large amount of underflow and the power generation is concentrated in this area.
Therefore, the reaction gas is deficient in a region far from both the manifold holes 8a and 8b other than the region. Therefore, water is accumulated in this region, especially when a highly humidified reaction gas is used. Also, when the gas flow path is a meandering shape consisting of a straight part and a turn part, paying attention to the forward path and the return path of the straight part in one flow path, the gas pressure difference between the inlet side and the outlet side is greater than that at the turn part. Since the flow rate is high, the base flow rate flowing through the gas diffusion layer is different even in the forward and return paths of the one flow path.

When the gas passage is composed of a plurality of grooves, it is difficult to uniformly control the gas distribution from the gas inlet side to the gas passage. Since the gas supply amount on the upstream side is relatively large on the downstream side, there is no difference in power generation performance. However, on the downstream side, the gas is consumed on the upper / middle stream side, and the absolute amount of gas decreases, so it is greatly affected by the initial distribution amount. That is, on the downstream side where gas distribution is poor, the battery performance deteriorates due to insufficient gas supply. Further, when the fuel is exhausted, there is a problem that carbon in the electrode is eluted to promote deterioration of cell performance.

[0008]

DISCLOSURE OF THE INVENTION The present invention solves the above problems and makes the ratio of the flow and the underflow in the gas flow path in the electrode surface uniform and realizes stable gas supply. Provide a separator plate. It is an object of the present invention to provide a polymer electrolyte fuel cell provided with such a separator plate.

[0009]

In order to solve the above-mentioned problems, the present invention provides an inlet side and an outlet side of a gas flow passage.
The cross-sectional area is increased to form a sub-manifold for keeping the gas pressure in the space constant. This sub-manifold eliminates non-uniformity of gas supply in the electrode surface, eliminates power generation distribution, and secures stable battery performance.

According to the present invention, long-term deterioration of performance of a fuel cell is gradually accumulated in the gas diffusion layer of the electrode,
Condensed water and generated water accumulate from the viewpoint that the unevenly distributed condensed water and generated water limit the gas flow in the gas diffusion layer to a narrow region and the other part is due to the decrease in power generation capacity. In order to make the battery structure less likely to be unevenly distributed,
Focusing on the gas flow in the gas diffusion layer. INDUSTRIAL APPLICABILITY The present invention is particularly effective when the gas passage of the separator plate is formed in a meandering shape, and forms a sub-manifold in which a volume per unit length in the gas passage direction is increased in a part of the gas passage. It is based on the finding that the reaction gas can be supplied to the electrode uniformly by doing so to enable stable operation of the fuel cell.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a hydrogen ion conductive polymer electrolyte membrane, a cathode and an anode sandwiching the hydrogen ion conductive polymer electrolyte membrane, and a gas flow path for supplying and discharging an oxidant gas to the cathode. A cathode-side conductive separator plate having, and an anode-side conductive separator plate having a gas flow path for supplying and discharging a fuel gas to and from the anode, and at least the cathode-side conductive separator plate and the anode-side conductive separator plate. One is a polymer electrolyte fuel cell having sub-manifolds having an increased cross-sectional area perpendicular to the electrodes on the inlet side and the outlet side of the gas flow channel.

In a preferred embodiment of the present invention, the gas flow passage has a meandering shape consisting of a straight portion and a turn portion extending substantially in parallel, and the sub-manifold is substantially parallel to the straight portion of the gas flow passage. Is growing. In this case, it is preferable that the sub-manifold has a length that extends substantially along the entire length of one side of the rectangular electrode.
The sub-manifold is preferably on the inlet side of the gas flow channel and / or on the outlet side of the gas flow channel. The separator plate supplies gas to the gas flow path.
An inlet-side manifold hole for discharging and an outlet-side manifold hole, and a sub-manifold at a connecting portion of the inlet-side sub-manifold with the inlet-side manifold hole or a connecting portion of the outlet-side sub-manifold with the outlet-side manifold hole It is preferable that the groove depth is the deepest.

In another preferred embodiment of the present invention, the separator plate supplies gas to the gas passage.
It has an inlet side manifold hole and an outlet side manifold hole for discharging, and the inlet side manifold hole or the outlet side manifold hole has the function of the sub-manifold. Furthermore, it is preferable to have a sub-manifold in the middle part of the gas flow path. It is preferable that the sub-manifolds are arranged more on the gas outlet side than on the gas inlet side. The cross-sectional area of the sub-manifold is preferably 1.2 times or more and 3.0 times or less than the cross-sectional area of the gas flow path.

The separator plate has an inlet-side manifold hole and an outlet-side manifold hole for supplying and discharging gas to and from the gas passage, and has a sectional area S _{1 of the} manifold hole and a sectional area S ₂ of the sub-manifold. Relationship is S ₁
/ 100 <preferable to satisfy S ₂ <S _1/25.

In still another preferred embodiment of the present invention, an inlet side sub-manifold and an outlet side sub-manifold extending in parallel to each other on the gas inlet side and the outlet side, and a plurality of gas flow paths connecting the both sub-manifolds are provided. Each gas flow path has a meandering shape, and the regions surrounded by each gas flow path are independent of each other. It is preferable that each of the gas flow paths has a meandering shape including a straight line portion that is inclined with respect to the sub-manifold and a turn portion that connects the straight line portion. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG. 1 shows a separator plate of this embodiment. The separator plate 11 is, for example, an isotropic graphite plate formed by machining, and has an oxidant gas inlet side manifold hole 12a.
And outlet side manifold hole 12b, fuel gas inlet side manifold hole 13a and outlet side manifold hole 1
3b and a gas flow path 17 connecting the manifold holes 12a and 12b. The gas flow path 17 is composed of four parallel grooves. The portions of the gas passage 17 that are connected to the manifold holes 12a and 12b form sub-manifolds 18a and 18b. The sub-manifolds 18a and 18b have a larger sectional area perpendicular to the electrode surface than the groove forming the gas flow path 17. In the illustrated example, the sub-manifolds 18a and 18
The width of b is larger than the width of the groove of the gas passage 17. Instead of increasing the width of the groove, the depth of the groove may be increased, or both the width and the depth of the groove may be increased.

The portion surrounded by the alternate long and short dash line 15 in the figure is the portion in contact with the cathode. The electrodes shown here are rectangular, and the sub-manifolds 18a and 18b extend along the longitudinal direction of the electrodes at positions corresponding to the short sides of the electrodes. The gas flow path 17 shown here is composed of a straight line portion extending along the longitudinal direction of the electrode and a turn portion substantially perpendicular to the straight line portion. The separator plate 11 has a flow path 17 for oxidant gas on one surface and a flow path for fuel gas similar to the flow path 17 on the other surface, and serves as both a cathode side separator plate and an anode side separator plate. There is. The fuel gas passage on the back side of FIG. 1 also has a sub-manifold as in the front side.

As described above, the separator plate 11 of the present embodiment has the meandering gas flow path 17 consisting of a straight outward path and a return path extending along the longitudinal direction of the electrode, and its inlet side and outlet side. On the side, sub-manifolds 18a and 1a having a large cross section having a length along substantially the entire length of the electrode
8b. In these sub-manifolds, the gas pressure is equalized, so that the ratio of the flow in the gas flow path 17 in the electrode surface to the underflow flowing in the gas diffusion layer of the electrode is made uniform, and stable gas supply can be realized.

FIG. 2 shows a modification of FIG. The separator plate 21 has sub-manifolds 28 a and 28 b on the inlet side and the outlet side of the gas flow path 27. These sub-manifolds are provided on the outer side of the electrode catalyst layer indicated by the chain line 25. However, the gas diffusion layer portion of the electrode has a size that covers the sub-manifolds 28a and 28b. Portions 29a and 29b connecting the sub-manifolds 28a and 28b and the manifold holes 12a and 12b are composed of four grooves. In this way, the effect does not change even if the sub-manifold is arranged outside the electrodes.

Embodiment 2 FIG. 3 shows a separator plate of this embodiment. In the first embodiment, the sub-manifold is provided only on the inlet side and the outlet side of the gas flow path 17, but the separator plate 3 shown here is provided.
1 is a sub-manifold 1 in the middle of the gas flow path 17.
8c. The sub-manifold 18c has its starting end connected to the upstream side of the gas flow path 17 and its ending end connected to the downstream side of the gas flow path. By forming a sub-manifold in the middle portion of the gas flow path 17, it is possible to make uniform the underflow in the gas diffusion layer of the electrode. In addition, when the gas utilization rate increases, the gas flow rate decreases, so that the gas distribution is likely to be affected downstream. When the sub-manifold is provided in the middle portion of the gas flow path, the gas distributed from the inlet-side sub-manifold is once gathered in the intermediate sub-manifold by the time it reaches the outlet-side sub-manifold, and the gas is redistributed. Therefore, the risk of gas shortage on the downstream side can be avoided. The separator plate 41 of FIG. 4 has two sub-manifolds 18c and 18 in the middle of the gas flow path.
This is an example in which d is provided. When a plurality of sub-manifolds are installed in the middle part of the gas flow passage, it is preferable to increase the installation ratio on the downstream side.

Embodiment 3 FIG. 5 shows a separator plate of this embodiment. This separator plate 51 is an example in which the width of the inlet-side and outlet-side submanifolds 58a and 58b is made larger than that of the previous embodiment. When the width of the groove forming the sub-manifold is increased, the weight of the separator plate cannot be applied to the electrode. So in the sub-manifold,
A plurality of ribs 59 are provided.

Embodiment 4 FIG. 6 shows a separator plate of this embodiment. The separator plate 61 includes an inlet side sub-manifold 68a and an outlet side sub-manifold 68b provided on the short side of the electrode.
The books are connected by a gas flow path 67. In the above-described embodiment, each gas flow path is composed of a forward path and a return path extending along the longitudinal direction of the electrode, and the forward path and the return path are parallel to each other. In the separator plate 61, the area covered by each gas flow path 67 is substantially independent. In FIG. 6, the gas flow path 67 has a zigzag shape inclined with respect to the sub-manifold. FIG. 7 shows a modification. The separator plate 71 includes a sub manifold 78a.
And 78b are connected by three gas flow paths 77. Each gas flow path 77 has an outward path and a return path parallel to the sub-manifold.

In the case where a plurality of gas flow paths are formed and each flow path is designed to have an independent flow path area in order to make the underflow in the gas diffusion layer of the electrode more uniform, each gas flow path should be linear. Is easy. However, in that case, it is difficult to obtain the pressure loss in the gas flow path unless the ratio of the longitudinal direction to the lateral direction of the electrode is secured to some extent. Therefore, by forming each gas flow path in a meandering shape, it is possible to secure a predetermined pressure loss even if the electrode has a shape close to a square. Thus, by forming a plurality of meandering gas flow paths and making the areas surrounded by the gas flow paths independent of each other, the length of the forward path and the return path of the meandering part is shortened, and The difference can be reduced as much as possible. At that time, as shown in FIG. 6, when the gas flow path is formed in a meandering shape composed of a straight line portion inclined with respect to the sub-manifold and a turn portion connecting the straight line portions, the gas diffusion layer sandwiched by the forward and return paths is formed. It is possible to make the yield flow uniform.

Embodiment 5 FIG. 8 shows a separator plate of this embodiment. The separator plate 81 is provided with oxidant gas inlet side manifold holes 82a and 82b corresponding to the two opposite sides of the electrode, and the manifold hole 82a has a right end portion in the drawing and a left end portion of the manifold hole 82b arranged in parallel. Four gas channels 87
I am in touch with. Reference numeral 83a denotes a fuel gas inlet side manifold hole, and 83b denotes an outlet side manifold hole. This separator plate is provided with a cooling water inlet side manifold hole 84a.
And an outlet side manifold hole 84b. In the present embodiment, the inlet-side manifold hole 82a and the outlet-side manifold hole 82b also serve as sub-manifolds. Since the inlet-side manifold hole 82a and the outlet-side manifold hole 82b are continuous with each cell, the gas diffusion layer of the electrode exposes the wall surface of the manifold hole,
Underground flows in and out of there. When the shapes of the inlet side manifold hole and the outlet side manifold hole are not limited, the effect of the sub-manifold can be more simply utilized by adopting the present embodiment.

Embodiment 6 FIG. 9 shows a separator plate of this embodiment. This separator plate 91 has a manifold hole 9 on the inlet side of the oxidant gas.
2a and outlet side manifold hole 92b, fuel gas inlet side manifold hole 93a and outlet side manifold hole 93b, and cooling water inlet side manifold hole 94.
a and an outlet side manifold hole 94b. The manifold hole 92a and the manifold hole 92b are connected by the sub-manifolds 98a and 98b, and four parallel meandering gas flow paths 97 connecting the both sub-manifolds.

Embodiment 7 FIG. 10 shows a separator plate of this embodiment. The separator plate 101 includes an oxidant gas inlet side manifold hole 102a and an outlet side manifold hole 102b, a fuel gas inlet side manifold hole 103a and an outlet side manifold hole 103b, and a cooling water inlet side manifold hole 104a and an outlet side manifold. Hole 104b
Have. The manifold hole 102a and the manifold hole 102b are the sub-manifolds 108a and 108.
b, they are connected by four parallel meandering gas flow paths 107 that connect both sub-manifolds. In this example, the sub-manifold 108 is provided in the middle of the gas flow path 107.
have c.

In the first to fifth embodiments, a separator plate having a flow path for oxidant gas on one surface and a flow path for fuel gas on the other surface, that is, a cathode side separator plate and an anode side separator plate is used. I explained what I could combine. The gas flow path and the sub-manifold are shown on the oxidant gas side. However, it is obvious that the same can be applied to the fuel gas side. Further, it goes without saying that the invention can also be applied to a separator plate having cooling water manifold holes. Although the internal manifold type in which the manifold plate is provided with the manifold holes has been described above, the present invention can be similarly applied to the external manifold type.

[0028]

Example 1 An acetylene black carbon powder having an average particle size of about 30
25% by weight of platinum particles of Å was carried to prepare an electrode catalyst. This catalyst powder was dispersed in isopropyl alcohol. Further, a powder of perfluorocarbon sulfonic acid was dispersed in ethyl alcohol. These two kinds of dispersion liquids were mixed to obtain an electrode paste. On the other hand, carbon paper with a thickness of 300 μm is made of polytetrafluoroethylene (PTFE).
A water-repellent gas diffusion layer was obtained by immersing in a water-based dispersion of 1. and drying treatment. A catalyst layer was formed by applying and drying the electrode paste on one surface of the gas diffusion layer. The electrolyte membrane-electrode assembly (MEA) is produced by sandwiching the polymer electrolyte membrane with the catalyst layer inside with the pair of electrodes produced as described above, and hot pressing at a temperature of 110 ° C. for 30 seconds. did. Here, as the polymer electrolyte membrane, perfluorocarbon sulfonic acid is 50 μm.
A thin film (Nafion manufactured by DuPont) was used. As the gas diffusion layer, in addition to the above-mentioned carbon paper, carbon cloth woven of carbon fibers as a flexible material, carbon felt mixed with carbon fibers and carbon powder and added with an organic binder, and the like. It can also be used.

As the conductive separator plate, a gas flow path as shown in FIG. 1 was formed by machining an isotropic graphite plate having a thickness of 3 mm. The gas flow path 17 was composed of four parallel grooves having a width of 0.7 mm and a depth of 0.3 mm. The sub-manifolds 18a and 18b are the inlet side manifold 1
2a and the outlet side manifold 12b. The sub-manifold had a groove width of 1.2 mm and a depth of 1.2 mm. Therefore, the cross-sectional area ratio of the sub-manifold to the gas flow path 17 is about 1.7 times,
The condition of 1.2 times or more and 3.0 times or less is satisfied.
In addition, the sectional area S ₁ of the manifold hole 12a is 100 mm ²
Because it is, and the cross-sectional area of the sub-manifold and S _2, which satisfies the _{S 1/100 <S 2 <} S 1/25.

The above conductive separator plate and MEA were alternately laminated to assemble a cell laminated body in which 50 cells were connected in series. This cell stack is sandwiched between stainless steel end plates via a current collector and an insulating plate, and both end plates are fastened with fastening rods.
Fastening was performed at a pressure of 10 kgf / cm ² . The battery of the comparative example has the same conditions as those of the present embodiment except that the entire region from the manifolds 8a to 8b has the same configuration as that of the gas passage 17 of the present embodiment as shown in FIG. The batteries of these examples and comparative examples were held at 85 ° C., and the anode side was kept at 83 ° C.
The fuel gas was humidified and heated so as to have a dew point of 1, and the air humidified and heated so as to have a dew point of 78 ° C. was supplied to the cathode side. Then, the current-voltage characteristics were examined at an oxygen utilization rate of 30% and a fuel utilization rate of 70%. The result is shown in FIG. A continuous power generation test was conducted at a current density of 0.3 A / cm ² . The result is shown in FIG.

In FIG. 11, the battery of this example shows only a small advantage in the low current density region, but at a high current density, the effect of having a sub-manifold appears, resulting in better battery performance. showed that. This is considered as follows. In the high current density region, the diffusivity of the reaction gas dominates the battery performance most, and it is necessary to supply the gas uniformly over the entire electrode surface. The underflow flow of gas in the gas diffusion layer of the electrode is governed by the gas pressure. In the battery of the present embodiment, the sub-manifold secures a wide range of regions where the gas pressure becomes equal on the gas inlet side and the gas outlet side of the electrode surface. For this reason, the underflow occurs more uniformly over the entire electrode surface, and a uniform gas supply is possible. The reason why the difference did not appear in the low current density region was that the rate-determining in the gas inlet side and the gas-outlet side was not due to diffusion rate control but due to reaction rate control. In the battery of the comparative example, the gas pressure is different in the gas passage corresponding to the sub-manifold of this embodiment.
That is, the pressure is highest in the portion close to the inlet side manifold hole, and the pressure is lowest in the portion close to the outlet side manifold. Therefore, as shown in FIG. 15, the gas flow is concentrated near the line connecting the manifolds 8a and 8b, and gas shortage occurs in the electrode portion located far from the line, and power generation distribution occurs. In particular, the battery performance is inferior at a high current density that is gas diffusion limited.

At the initial stage of the continuous power generation test of FIG. 12, there is almost no difference. However, with the passage of time, irreversible deterioration such as elution of carbon powder used in the electrode and coating resin in the vicinity of the catalyst occurred in the electrode portion where gas was insufficient in the comparative battery. As a result, the power generation is concentrated more in the portion where the gas supply is relatively rich from the initial stage, and the current density increases, so that the battery performance deteriorates over time. On the other hand, in the battery of the present example, stable gas supply to the entire electrode surface prevents deterioration due to gas shortage as in the comparative example, so that the battery voltage is equal to the initial value even after 2000 hours. The value is maintained. As described above, it was confirmed that by providing the sub-manifold in the gas flow path of the separator plate, the gas can be uniformly supplied to the entire electrode surface and the battery performance can be improved.

Example 2 In this example, as shown in FIG. 3, in addition to the sub-manifolds 18a and 18b of Example 1, a sub-manifold 18c was further formed in the middle portion of the gas flow path 17. A battery was produced under the same conditions as in Example 1 except for the above. The battery of this example and the battery of Example 1 were held at 85 ° C.
Fuel gas humidified and heated to have a dew point of 3 ° C was supplied, and air humidified and heated to have a dew point of 78 ° C was supplied to the cathode side. And current density of 0.3 A / cm
^{2. The} fuel utilization rate was set to 70%, and the oxygen utilization rate was variously changed for the test. The result is shown in FIG. From the results of FIG. 13, it can be seen that in the region where the oxygen utilization rate is high, the battery of this example maintains stable battery performance without causing a voltage drop. This is because the sub-manifold 18c was further provided in the battery of Example 1 so that the underflow in the gas diffusion layer could be made uniform. When the oxygen utilization rate is high, the gas flow rate is decreased, so that the gas distribution is easily affected on the downstream side. By forming the sub-manifold in the middle portion, the gas distributed from the manifold hole 12a is once collected before reaching the manifold hole 12b, and the gas is redistributed. This avoids the risk of gas shortage on the downstream side.

Further, when the oxygen utilization rate becomes higher, the ratio of the generated water to the gas flow rate becomes higher, and the condensed water and the generated water are more likely to block the gas flow path. At the same time, the pressure loss when the gas passes through the gas passage decreases, and when water is blocked in the gas passage, the restoring force for removing the water and returning it to the original state decreases. Then, the gas cannot be supplied to the gas flow path after the closed point. If there is a sub-manifold in the middle of the gas flow path, gas can be redistributed so that gas can be supplied to the downstream side of the closed point, and the effect on the battery performance due to the blockage of the gas flow path can be minimized. The effect is obtained. In the same manner as above, as a result of conducting a test with the oxygen utilization rate kept constant and the hydrogen utilization rate varied, as with the oxygen utilization rate, the higher the utilization rate, the more stable the battery performance of this example. It was confirmed that When a gas obtained by reforming city gas was assumed as the anode gas and a mixed gas of 80% hydrogen and 20% carbon dioxide was used, the effect was remarkable. When the number of sub-manifolds installed in the middle part of the gas flow path is plural, it has been confirmed that increasing the installation ratio on the downstream side is effective, as shown in FIG.

Example 3 In this example, the case of increasing the groove width of the sub-manifold in the battery of Example 1 as shown in FIG. 5 was verified. A battery was manufactured with the sub-manifolds 58a and 58b having a width of 2.8 mm and a groove depth of 0.8 mm. The cross-sectional area perpendicular to the electrode surface of this sub-manifold is about 2.7 times that of the gas passage 17. Here, if the groove width becomes wide, it becomes impossible to apply a weight to the electrode surface, so that as shown in FIG.
Was set up. The current-voltage characteristics of this battery were examined under the same conditions as in Example 1. As a result, the same performance as that of Example 1 was exhibited. Therefore, it was confirmed that it is effective to install the rib inside the groove when forming the sub-manifold having a wide groove width.

Further, the effect of the sub-manifold was recognized when the cross-sectional area of the sub-manifolds 58a and 58b was 1.2 times or more and 3.0 times or less that of the gas passage 17.
Similarly, the cross-sectional area S ₁ of the manifold holes 12a or 12b, when the cross-sectional area of the sub-manifold 58a or 58b was S _2, the effect was observed in the _{S 1/100 <S 2 <} S 1/25.

Example 4 In this example, two types of batteries were manufactured. In the sub-manifold 18a according to the first embodiment, the groove depth of the connection portion with the manifold hole 12a and the connection portion with the manifold hole 12b of the sub-manifold 18b is processed to be the deepest in the sub-manifold, The battery is designed to be the shallowest in the manifold. These batteries were tested by changing the dew point of humidified air supplied to the cathode side. As a result, the battery having a shallow groove depth at the connecting portion with the manifold hole of the sub-manifold has a lower dew point than the battery having a deep groove depth, resulting in lower battery performance. Since the groove depth of the connecting part is shallow, it becomes difficult to discharge the condensed water or generated water at the gas outlet side when the amount of water increases, and the condensed water or generated water accumulates in the sub-manifold. This is because the function of is lost. On the other hand, in the battery in which the groove depth of the connecting portion is deep, the condensed water and the generated water can be discharged smoothly, so that the battery performance does not deteriorate even in a humidified state where the supply gas is high. In this embodiment, the sub-manifold on the cathode side has been described, but the same tendency is observed for the sub-manifold on the anode side. From the above, it is preferable that the groove depth of the connecting portion with the manifold hole of the sub-manifold be the same as or deeper than the other portions in the sub-manifold.

[0038]

According to the present invention, it is possible to provide a fuel cell exhibiting a highly efficient and stable performance by temporarily making the gas pressure uniform in the sub-manifold.

[Brief description of drawings]

FIG. 1 is a front view of a cathode side of a separator plate of a fuel cell according to an embodiment of the present invention.

FIG. 2 is a front view of a cathode side of a separator plate according to another embodiment of the present invention.

FIG. 3 is a front view of a cathode side of a separator plate according to still another embodiment of the present invention.

FIG. 4 is a front view of the cathode side of the separator plate according to the embodiment of the present invention.

FIG. 5 is a front view of a cathode side of a separator plate according to another embodiment of the present invention.

FIG. 6 is a front view of a cathode side of a separator plate according to another embodiment of the present invention.

FIG. 7 is a front view of a cathode side of a separator plate according to still another embodiment of the present invention.

FIG. 8 is a front view of a cathode side of a separator plate according to another embodiment of the present invention.

FIG. 9 is a front view of a cathode side of a separator plate according to still another embodiment of the present invention.

FIG. 10 is a front view of the cathode side of the separator plate according to the embodiment of the present invention.

FIG. 11 is a diagram showing current-voltage characteristics of fuel cells of Examples and Comparative Examples of the present invention.

FIG. 12 is a diagram showing changes in voltage in a continuous power generation test of a fuel cell according to an example of the present invention.

FIG. 13 is a diagram showing a relationship between oxygen utilization rate and voltage of fuel cells of Examples and Comparative Examples of the present invention.

FIG. 14 is a cross-sectional view of a main part of a typical fuel cell.

FIG. 15 is a front view of a cathode side of a separator plate of a conventional fuel cell.

[Explanation of symbols]

11 Conductive separator plate 12a Oxidizing gas inlet manifold hole 12b Oxidant gas outlet side manifold hole 13a Fuel gas inlet side manifold hole 13b Fuel gas outlet side manifold hole 17 gas flow path 18a, 18b Sub-manifold

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[Procedure amendment]

[Submission date] March 27, 2002 (2002.3.2)
7)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 11

[Correction method] Change

[Correction content]

FIG. 11

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   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroki Kusakabe             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Hideo Ohara             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Shin Kobayashi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Nobuhiro Hase             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor, Hajime Shibata             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Kuro Gyoten             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5H026 AA06 CC03 CC08 HH02

Claims (12)

[Claims] 1. A cathode-side conductive separator having a hydrogen ion conductive polymer electrolyte membrane, a cathode and an anode sandwiching the hydrogen ion conductive polymer electrolyte membrane, and a gas flow path for supplying and discharging an oxidant gas to the cathode. A plate and an anode-side conductive separator plate having a gas flow path for supplying and discharging a fuel gas to and from the anode, and at least one of the cathode-side conductive separator plate and the anode-side conductive separator plate is the gas flow. A polymer electrolyte fuel cell, comprising sub-manifolds having an increased cross-sectional area perpendicular to the electrodes on the inlet side and the outlet side of the passage. 2. The gas flow path has a meandering shape consisting of a straight portion and a turn portion that extend substantially in parallel, and the sub-manifold extends substantially parallel to the straight portion of the gas flow passage. The polymer electrolyte fuel cell described. 3. The polymer electrolyte fuel cell according to claim 1, wherein the sub-manifold is located on the inlet side of the gas flow path. 4. The polymer electrolyte fuel cell according to claim 1, wherein the sub-manifold is located on the outlet side of the gas flow path. 5. The separator plate is provided with an inlet-side manifold hole and an outlet-side manifold hole for supplying / discharging gas to / from the gas flow path, and a connecting portion of the inlet-side sub-manifold with the inlet-side manifold hole or The polymer electrolyte fuel cell according to claim 1, wherein a groove depth of the sub-manifold is the deepest at a connecting portion of the outlet-side sub-manifold with the outlet-side manifold hole. 6. The separator plate comprises an inlet side manifold hole and an outlet side manifold hole for supplying / discharging gas to / from the gas flow path, and the inlet side manifold hole or the outlet side manifold hole functions as the sub-manifold. The polymer electrolyte fuel cell according to claim 1, further comprising: 7. The polymer electrolyte fuel cell according to claim 1, further comprising a sub-manifold in an intermediate portion of the gas flow path. 8. The polymer electrolyte fuel cell according to claim 7, wherein the sub-manifold is arranged more on the gas outlet side than on the gas inlet side. 9. The polymer electrolyte fuel cell according to claim 1, wherein the cross-sectional area of the sub-manifold is 1.2 times or more and 3.0 times or less the cross-sectional area of the gas flow path. 10. The separator plate is provided with an inlet-side manifold hole and an outlet-side manifold hole for supplying / discharging gas to / from the gas passage, and the sectional area S _{1 of the} manifold hole and the sectional area S of the sub-manifold. The relationship of ₂
S _1/100 <S ₂ <polymer electrolyte fuel cell according to claim 1, wherein satisfying the S _1/25. 11. An inlet side sub-manifold and an outlet side sub-manifold extending in parallel to each other on the gas inlet side and the outlet side, and a plurality of gas flow channels connecting the both sub-manifolds, each gas flow channel having a meandering shape. Have
The polymer electrolyte fuel cell according to claim 1, wherein the regions surrounded by the gas flow paths are independent of each other. 12. The polymer electrolyte fuel cell according to claim 11, wherein each of the gas flow paths has a meandering shape composed of a linear portion inclined with respect to the sub-manifold and a turn portion connecting the linear portions.