JP2585770B2 - Fuel cell and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell, and more particularly to a structure of an electrode suitable for equalizing temperature distribution in the electrode and a method of manufacturing the electrode.

[Conventional technology]

Conventionally, as a measure for improving the performance of a fuel cell, making the temperature distribution uniform or extending the life, Japanese Patent Application Laid-Open No. 56-1344 shown in FIG.
As shown in the technology of No. 73, the technology of JP-A-62-40168 shown in FIG.
Alternatively, the gasket is partially meandered, and the former has attempted to improve the performance by improving the gas utilization rate, and the latter has attempted to make the temperature distribution uniform.

[Problems to be solved by the invention]

In these prior arts, in the former case, a large amount of gas is introduced into the inlet side of the flow path 50 formed between the ribs 2, so that the reactive gas distribution is maintained high, and the electromotive force is large and a large current flows. Expands. In the latter, the flow path 50 is divided into a straight section and a meandering section, and both are adjacent to each other. However, equivalently, only the electrode is divided into two, and the temperature distribution is essentially improved. Not. As the development trend of the fuel cell, there is a tendency that the size of the electrode is increased and the current density is increased in order to reduce the cost and the size of the fuel cell. Therefore, it is necessary to equalize the temperature distribution, equalize the performance in the electrode plane, and prolong the battery life.

An object of the present invention is to solve the above problems, provide a fuel cell having a uniform temperature distribution and a long life, provide a functional manufacturing method with a simple process of the fuel cell, and improve the temperature distribution. It is an object of the present invention to provide a control method for further equalizing.

[Means for solving the problem]

The object is to provide a fuel cell in which a passage for introducing a reactant gas is provided inside an electrode surface, wherein the reactant gas passage has a portion in which a single gas passage reverses the flow direction of the reactant gas at least twice. Providing a fuel cell in which a reaction gas passage is disposed adjacent to the inside of the electrode surface, and a plurality of unit cells, which are units for generating power by a cell reaction, are welded with a heat-fusible resin and the unit is passed through a cooler. Provided is a method of manufacturing a fuel cell in which a plurality of cells are alternately stacked, measuring a fuel cell outlet temperature and a fuel cell load current value of a reactant gas, and adjusting a fuel cell inlet temperature of the reactant gas to a fuel cell outlet temperature of the reactant gas. This is achieved by providing a fuel cell control method for controlling a refrigerant or a heat medium to be supplied to a heat exchanger provided at a fuel cell inlet of the reaction gas so as to have a lower value.

[Action]

The reaction gas concentration is high at the entrance of the reaction gas passage in the electrode surface, so the heat generated by the reaction is high due to the high concentration of the reaction gas, and the temperature rises. The heat is low and the temperature is low. As described above, since the high-concentration high-temperature portion and the low-concentration low-temperature portion are adjacent to each other in all portions of the reaction gas passage, the temperatures of both reaction gas passages are averaged in all portions. In addition, the reaction gas passages are arranged as a plurality of parallel flows in the electrode surface, so that they are averaged over the entire area in the electrode surface.

Also, the electrodes and separators of the unit cells constituting the fuel cell have the same structure, a plurality of unit cells are fixed by heat fusion to form a block, and the block and the cooler are mutually laminated to position in the height direction. No deviation occurs. This makes it possible to equalize the temperature distribution by setting the reaction gas at the opposed position between the unit cells to different concentrations. Further, by controlling the temperature control means provided at the fuel cell inlet so that the fuel gas inlet temperature of the reaction gas is lower than the outlet temperature, the temperature protrusion near the inlet of the reaction gas passage is suppressed, and the temperature is further reduced. The rise can be averaged.

〔Example〕

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a configuration of, for example, a phosphate type unit cell showing one embodiment of the present invention. The unit cells 1a and 1b include air electrodes 4a and 4b each including a ribbed electrode having a rib 2 and a peripheral portion 3 that uses a gas seal in combination, and fuel electrodes 5a and 5b each having substantially the same configuration as the above. Catalyst 6 sandwiched between both poles,
And a matrix 7. In a fuel cell as an actual power generation device, the unit cells 1a and 1b
Are alternately stacked.

With this configuration, the reaction gas is introduced to generate electric power, but the fuel side operates in the same manner. The air 9a introduced into the unit cell 1a passes through the gas passages 51a, 52a, 53a as indicated by arrows, and flows through the cell 2a.
It is inverted and discharged out of the system. On the other hand, the air 9b introduced into the unit cell 1b is configured such that the direction of reversal of the gas flow in the cell is opposite to that of the unit cell 1a,
The gas enters the gas passage 53b corresponding to the outlet gas passage 53a of the unit cell 1a, and is discharged out of the cell via 52b and 51b. The other gas passages arranged in parallel have the same configuration.

When power is continuously generated as described above, the temperature of the cell rises due to the heat generated by the battery reaction. Generally, the higher the reaction gas concentration, the larger the amount of reaction on the inlet side, so that a large amount of current flows, the temperature rises greatly, and the performance decreases over time. In addition, at the outlet side of the reaction gas, the partial pressure of water vapor becomes extremely high due to the water generated by the reaction of hydrogen and oxygen, the concentration of phosphoric acid in the matrix is lowered, the state becomes highly corrosive, and corrosion of the electrode with ribs, separators, etc. To accelerate.

Considering the temperature rise at the positions corresponding to the gas passages at the positions AA and BB in the invention of FIG. 1, the position of the gas passage 51a crossing AA has a high gas concentration and the temperature rise. However, since the gas concentration in the adjacent gas passages 52a is low and the temperature rise is small, they are averaged together. Hereinafter, all the paths on AA operate in the same manner. Next, looking at BB, the temperature on the gas passage 53a where the temperature rise is the smallest is increased by the adjacent gas passage 52a having a relatively high gas concentration, and is averaged. Hereinafter, all of the passages on BB operate similarly.

In addition, since the gas passages of the air electrodes 4a and 4b are reversed in the reverse direction to the provision electrodes 5a and 5b, the intersection of the gas passage 51a and the A-A where the temperature of the air electrode 4a becomes the highest is The temperature is lowered by the intersection of AA with the gas passage 51b of the air electrode 4b having a relatively low temperature. On the other hand, the temperature at the intersection of the gas passage 53a having the lowest temperature of the air electrode 4a and BB is raised by the intersection of the gas passage 53b having a relatively high temperature of the air electrode 4b and BB. Therefore, the temperature distribution in the cell is further equalized.

When the temperature distribution of this embodiment is compared with the conventional example shown in FIG. 16, the temperature distribution of this embodiment is shown in FIG. 2, and the temperature distribution of FIG. 16 of the conventional example is shown in FIG. Is about
Reduced to 43%.

Further, the phosphate concentration in the matrix in H ₃ PO ₄ ratio, the first
In the conventional example shown in FIG. 6, H ₃ PO ₄ is converted to P ₂ O _{5 at} the inlet of the reaction gas.
However, in the present embodiment, since the gas passages having different partial pressures of the steam are adjacent to each other, the water vapor moves along the porous gas passage wall and is averaged.
The range was about 96%, which was about 25% of the conventional concentration range.

In addition, as shown in FIG. 4, the time-dependent characteristics of this battery were found to be able to reduce the voltage drop rate to about half that of the conventional example.

FIG. 5 shows an example in which the same unit cells are stacked. Sixth
The figure shows the temperature distribution. Since there is no equalizing effect between the unit cells, the temperature at the intersection between the gas passages 51a and AA tends to be high, and the temperature at the intersection between the gas passages 53a and BB tends to be low. Reduced to 55% of the conventional example. At the same time, in this embodiment, electrodes of the same shape can be overlapped and used, so that a fuel cell can be manufactured at low cost. In addition, the concentration of phosphoric acid was made the same as that of the embodiment shown in FIG. 1 because the partial pressure of water vapor in the reaction gas became dominant.

FIG. 7 shows an embodiment in which the manifold 10 has a function of reversing the gas flow. The air 9a flowing into the electrode 4 is reversed twice by the barrier 11 fixed to the manifold 10, and then discharged out of the cell. Therefore, in this example, the same effect as that of FIG. 4 can be obtained, and the shape of the electrode 4 is very simplified, so that the production becomes easy.

8 and 9 show a method of manufacturing a fuel cell according to the present invention, in which unit cells of the embodiment shown in FIG. 1 are stacked. Since a stacked battery usually has 200 to 300 unit cells stacked, if the parts such as the separator 8 and the electrodes 4a and 5a are disjointed, misalignment occurs during the stacking, and the opposition between the unit cells, which is the point of the present invention, is considered. It may not be possible to achieve the purpose of equalizing the temperature distribution by setting the reaction gas at different positions to different concentrations. This embodiment solves this point.

Normally, 5 to 8 unit cells are stacked between the coolers 18, so that the unit cells 1a, 1b and the separator 8 are not opened at the stacking end face like the gas passages 52a, 53a, 51b, 52b. The spot welding portion 16 is heat-fused with a heat-fusible resin such as a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin (hereinafter abbreviated as PFA) to form a block 17. By alternately stacking the obtained blocks 17 with the cooler 18, the batteries can be easily stacked, and the spot welding does not cause displacement of the gas passages 51a and 51b, for example. Thus, a simplified and functional fuel cell manufacturing method can be provided without obstructing the equalization of the temperature distribution.

10 to 14 show a ribbed electrode having a function of reversing a gas flow, a ribbed separator, and a method of manufacturing the same. No.
FIG. 10 shows a ribbed electrode, and FIG. 11 shows a ribbed separator.
Since the manufacturing methods are almost the same in each case, examples of the ribbed electrode will be described with reference to FIGS.

The ribbed electrode 19 in FIG. 10 is provided with an extended portion 22 around its periphery, and a frame-shaped peripheral portion 3c having the same thickness as this is provided. At this time, it is preferable that the inner dimension of the frame-shaped peripheral portion 3c is younger than the outer dimension of the ribbed electrode 19. Then, the peripheral portions 3a and 3b are arranged via the bonding film 20, and the bonded portion is heated to a temperature of 320.
Heat to ~ 350 ° C and pressurize at a pressure of 5-10 kg / cm ² to form a single piece.

The ribbed separator 21 of FIG. 11 has a porous rib 2 fixed to both surfaces of a flat separator 8 so as to be orthogonal to each other.
In addition, the dimension of the separator 8 is made larger than the length of the rib 2 and an extension 22 is provided. As in the case of the electrode with ribs, the peripheral portions 3a and 3b are heat-sealed with the adhesive film 20 to the extension portion 22 to be integrally formed.

The parts A and B in FIG. 10 are enlarged and shown in FIGS. 12 and 13.
For the peripheral portions 3a, 3b, 3c, a polyimide film having a small coefficient of thermal expansion is preferable, whereby deformation such as warpage at the time of thermal fusion can be extremely reduced. The bonding film 20 preferably has a sandwich structure of a polyimide film at the center and a PFA film at both sides, so that it can be surely integrated without deformation at the time of heat fusion. In addition, since it is difficult to mount the peripheral portion 3b in a small chip shape,
As shown in FIG. 14a and FIG. 14b, it is convenient to use a bonding film 20 to which a predetermined number of long peripheral portions 3b are attached and cut to a predetermined size W.

When manufactured as described above, a ribbed electrode and a ribbed separator having a reversal function with good thermal stability can be obtained.

FIG. 15 shows a control method for equalizing the temperature distribution, which is preferably applied to a fuel cell of the type in which gas flows are reversed in the same direction as in the invention of FIG.

That is, the signal of the temperature sensor 23 for measuring the battery outlet gas temperature and the load signal are taken into the control computer 264, and when the temperature of the air and fuel on the introduction side is lower than the battery outlet gas temperature and the load is small, the temperature range is reduced. When the value is small and large, the refrigerant or the heat medium supplied to the heat exchanger 25 is controlled so that the temperature width becomes large. This results in FIG. 6,
The protrusion of the temperature as shown at the position AA is eliminated, and the temperature distribution can be further equalized.

〔The invention's effect〕

According to the present invention, by providing a passage for inverting the flow of the reaction gas, the reaction gas passages having different reaction gas concentrations can be adjacent to each other to average the temperature distribution in the cell and the concentration distribution of the electrolytic solution. Can be obtained.

In addition, since a plurality of cells can be fixed and manufactured in a block, the temperature distribution can be averaged reliably, and the cells can be easily stacked.

Furthermore, since the inlet temperature of the reaction gas can be properly controlled,
The effect that the temperature distribution of the cell becomes uniform can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a cell showing one embodiment of the present invention, FIG. 2 is a temperature distribution chart of the present embodiment, FIG. 3 is a temperature distribution chart of the prior art, FIG. FIG. 5 is a perspective view showing another embodiment of the present invention, FIG. 6 is a temperature distribution chart of the cell shown in FIG. 5, FIG. 7 is a plan view showing another embodiment of the present invention, FIG. FIG. 9 is a front view showing a method of manufacturing the battery of the present invention, FIGS. 10 to 13 are perspective views showing a method of manufacturing the component of the present invention, FIG. 14a is a plan view of the component of the present invention, and FIG. FIG. 14 is a front view of FIG. 14a, FIG. 15 is a diagram showing an embodiment of the control method of the present invention, and FIGS. 16 and 17 are plan views showing a conventional example. 1a, 1b ... unit cell, 2 ... rib, 3 ... peripheral part,
4a, 4b… air electrode, 5a, 5b… fuel electrode, 9a, 9b… air, 51a-53a, 51b-53b… gas passage, 10… manifold, 11… barrier, 12… exit sub Manifold, 13… Inlet sub-manifold, 14… Blower, 16… Spot welding, 17… Block, 18… Cooler,
19 ... Ribbed electrode, 20 ... Adhesive film, 21 ... Ribbed separator, 22 ...
... Extension, 23 ... Temperature sensor, 24 ... Control computer, 25 ... Heat exchanger.

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yasuyuki Tsutsumi 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (56) References JP-A-58-164157 (JP, A) JP-A-1- 134869 (JP, A) JP-A-2-86070 (JP, A) JP-A-56-134473 (JP, A)

Claims (10)

(57) [Claims] 1. A fuel cell in which a passage for introducing a reaction gas is provided inside an electrode surface, wherein the reaction gas passage has a single passage and a portion in which a flow direction of the reaction gas is reversed at least twice. Wherein the reaction gas passages are disposed adjacent to each other inside the electrode surface. 2. A fuel cell in which a passage for introducing a reactant gas is provided inside an electrode surface, wherein the reactant gas passages having mutually different reactant gas flow directions are different from each other and the reactant gas flow directions adjacent to each other are in the same direction. A fuel cell, wherein at least one or more combinations with the reaction gas passages having different concentrations of the reaction gas are provided inside the electrode surface. 3. The fuel cell according to claim 1, wherein the electrodes having different flow directions of the inflowing reactant gas are alternately stacked. 4. The electrode is provided with a manifold for simultaneously supplying the reaction gas to each of the reaction gas passage supply sides and a manifold for simultaneously exhausting the reaction gas to each of the reaction gas passage exhaust sides. The fuel cell according to claim 1, wherein 5. The electrode is plate-shaped, a plurality of ribs are provided on one plane to form the reaction gas passage, and a part of the rib is cut off to form a reversing part for reversing the flow of the reaction gas. 2. The fuel cell according to claim 1, wherein a peripheral portion of the plate-shaped flat surface is further extended to provide an extended portion. 6. A fuel cell having a flat separator between unit cells, which are units for generating power by a battery reaction, wherein a rib on one surface and a rib on the other surface are provided on both surfaces of the flat separator. A plurality of ribs are provided so that the ribs are orthogonal to each other, and a passage for the reaction gas is formed on both surfaces of the separator, and a part of the rib forming the reaction gas passage is cut out to flow the reaction gas. A fuel cell, wherein a plurality of reversing portions are formed in a single passage and a peripheral portion of the flat separator is extended outward from the rib to provide an extension. 7. A passage for introducing a reaction gas for performing a battery reaction is provided inside the electrode surface, wherein the reaction gas passage has a single passage and a portion where the flow direction of the reaction gas is reversed at least twice at least. A fuel cell comprising a plurality of unit cells arranged adjacent to each other in the electrode surface adjacent to each other by a heat-fusible resin to form a block, and the block and the cooler are alternately stacked. Manufacturing method. 8. A fuel cell according to claim 5, wherein the extension and the periphery of the ribbed electrode extending from the plate-shaped planar peripheral portion and the peripheral portion are made of an ethylene fluoride / perfluoroalkyl vinyl ether copolymer resin film / polyimide / fluoride. A method for producing a fuel cell, comprising: using a bonding film made of an ethylene / perfluoroalkylvinyl ether copolymer resin film to be integrated by heat fusion. 9. An extension of the plate-shaped separator according to claim 6, wherein the extension is extended outward and the periphery is an ethylene fluoride / perfluoroalkyl vinyl ether copolymer resin film / polyimide / ethylene fluoride A method for producing a fuel cell, comprising: using a bonding film made of a fluoroalkyl vinyl ether copolymer resin film to be integrated by heat fusion. 10. A passage for introducing a reaction gas for performing a battery reaction is provided inside the electrode surface, and the reaction gas passage has a portion where a single passage reverses the flow direction of the reaction gas at least twice and flows thereinto. A fuel cell outlet gas temperature signal and a load signal of a fuel cell in which a plurality of the electrodes having the same flow direction of the reactant gas are alternately stacked are input to a computer, and the computer detects the reactant gas temperature on the fuel cell inlet side. The refrigerant supplied to the heat exchanger provided on the fuel cell inlet side of the reaction gas such that the temperature width is smaller than the fuel cell outlet gas temperature, and when the load is small, the temperature width is small, and when the load is large, the temperature width is large. A method for controlling a fuel cell, comprising controlling a heat medium.