JP2004265877A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell that can be used easily as a dry battery. <P>SOLUTION: A square unit cell 5 has an anode 3 provided on the buck side of an electrolyte film and a cathode 4 provided on the front side thereof. The unit cell 5 is placed on an insulative square column container 6 for storing hydrogen. The fuel cell has a square column structure, in which the stacked body of unit cells 5 is pressed down by an insulative pressing plate 7 and fixed by fixtures 13 and 14. An inlet 12 for supplying hydrogen is provided in the bottom side of the container 6. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a fuel cell, and more particularly to a fuel cell that is easy to carry.

  A fuel cell uses a single cell in which an anode and a cathode are arranged on an electrolyte membrane as a basic unit, and supplies a hydrogen-rich fuel gas to the anode and an oxidizing gas such as air to the cathode to generate power.

  Since the practical voltage per unit cell is as low as about 0.6 V, a fuel cell generally put into practical use has a structure in which unit cells are stacked in order to obtain a high voltage. A compact fuel cell in which a single cell structure as disclosed in Japanese Patent Application Laid-Open No. 5-176934 is arranged in a plane has also been developed.

  FIG. 14 is an exploded perspective view showing the structure of the single cell structure described in this publication. The single cell structure 110 is configured such that a single cell in which an anode 103 and a cathode 104 are disposed on an electrolyte membrane 102 is sandwiched between insulating pressing plates 108 and 109 via current collector plates 105 and 106 and a pair of terminal electrodes 111 , 112 and a pair of crimping members 113...

  Anode gas (hydrogen) is supplied to the anode 103 from a window formed in the insulating press plate 113 and the current collector 105, and the cathode 104 is set to the insulating press plate 109 and the current collector 106. The cathode gas (air) is supplied from the window.

Such a single cell structure is capable of obtaining a high voltage and being formed in a desired shape by connecting a plurality of the single cell structures in a matrix and electrically connecting them in series by contacting terminal electrodes. Can be easily assembled.
JP-A-5-176934

  Based on the fuel cell having such a single-cell structure, if a battery such as a dry battery, which can be used alone or by connecting several batteries, can be used easily, it can be expected to be widely used as a power source for portable equipment.

  However, the single cell structure disclosed in the above publication has been developed so that a high voltage can be obtained by connecting a plurality of the single cell structures, and a manifold is provided for the single cell structures arranged in a matrix. Then, it is designed to operate while supplying anode gas and cathode gas, and it takes time and effort to actually install the manifold, so it is not suitable for use alone or in a small number as it is Did not.

  The present invention has been made in view of the above problems, and provides a fuel cell having a single cell structure that can be easily used like a dry cell by connecting one or several cells. With the goal.

  In order to achieve the above object, the present invention provides a fuel cell having a fuel gas storage chamber therein, an opening in a part of a vessel wall, and a fuel gas storage chamber in another part of the vessel wall. A fuel gas storage container having a supply port for replenishing the fuel gas from the outside, and a single cell having a structure in which an electrolyte membrane is sandwiched between an anode and a cathode, and provided with the anode side facing the opening. And a plate seated on the cathode of the single cell with the air hole provided at the center facing the opening.

  In such a fuel cell, outside air is automatically supplied to the cathode through the air hole. On the other hand, the fuel gas in the container is supplied to the anode through the opening. Therefore, power can be easily generated without providing a manifold or the like for feeding fuel gas or air, and use as a dry battery is possible.

  In addition, if the amount of fuel gas stored in the container decreases, the fuel gas can be replenished at any time from the replenishing port, and can be used repeatedly as a secondary battery.

  Here, if the air holes are made openable and closable by the open / close lid, it is possible to prevent the electrolyte membrane from coming into contact with the outside air during battery storage. Then, the state of the electrolyte membrane at the time of storage can be suppressed from changing, and a decrease in battery performance can be prevented.

  For example, in the case of a polymer electrolyte fuel cell, the electrolyte membrane can be prevented from drying, and in the case of a phosphoric acid fuel cell, the deliquescence of phosphoric acid as an electrolyte can be prevented. If present, a change in the concentration of the aqueous potassium hydroxide solution as the electrolyte can be prevented.

  Further, if an auxiliary air hole is opened substantially in parallel with the main surface of the single cell so as to communicate with the air hole with respect to the plate, air is taken in from the auxiliary air hole, heated by the cathode, and heated from the air hole. Since a smooth air flow is generated by natural convection, which is discharged, the supply of air to the cathode is promoted, and power can be generated at a higher current density.

  Here, if the air hole and the auxiliary air hole are made openable and closable by the open / close lid, it is possible to prevent the electrolyte membrane from coming into contact with the outside air during battery storage.

  According to the present invention, the fuel cell has a fuel gas storage chamber inside, an opening is provided in a part of the vessel wall, and the storage chamber is supplied with fuel gas from the outside to the other part of the vessel wall. And a single cell having an electrolyte membrane sandwiched between an anode and a cathode, with the anode side facing the opening, and air provided in the center. By forming the hole with the plate body seated on the cathode of the single cell in a state of facing the opening, it can be used easily and repeatedly as a dry battery.

  Further, by providing the auxiliary air holes in the plate, the supply of air to the cathode is promoted, and it is possible to suppress a decrease in voltage when operating at a high current density.

  In addition, if the air holes and the auxiliary air holes of the plate are covered with an opening / closing lid during storage of the battery, it is possible to prevent a decrease in battery performance during storage.

  The configuration of the polymer electrolyte fuel cell 1 according to the present invention will be described in detail with reference to the drawings.

  1 is an assembly view of a main part of the fuel cell 1, FIG. 2 is an external perspective view of the fuel cell 1, and FIG. 3 is a sectional view taken along line XX.

  The fuel cell 1 includes a square single cell 5 in which an anode 3 and a cathode 4 are arranged on an electrolyte membrane 2, and a anode 3 on a top surface of a square pillar-shaped hydrogen storage container 6 via a current collector 8. A laminated body which is mounted with its sides facing each other and pressed from above by a rectangular pressing plate 7 via a current collecting plate 9 is pressed and fixed in the laminating direction by pressing members 13 and 14 and fixed. It is a columnar structure.

  The electrolyte membrane 2 is, for example, a fluorocarbon-based ion exchange membrane (for example, Nafion: trade name, manufactured by DuPont) having a size of 10 cm × 10 cm and a thickness of about 0.2 mm. Is formed with an anode 3 and a cathode 4 which are each about 5 cm × 5 cm in size and about 0.1 mm thick and made of graphite carrying platinum.

  The container 6 is a square pillar-shaped molded body in which a space for storing hydrogen, that is, a hydrogen gas storage chamber is perforated. The upper surface of the container wall has the same dimensions as the electrolyte membrane 2 and the anode 3 A window 10 for supplying hydrogen gas of the same size as that of the above is provided.

  At the bottom of the vessel wall of the container 6, a supply port 12 (see FIG. 3) for supplying hydrogen gas from the outside is provided. The supply port 12 shown in FIG. 3 is formed by inserting a rubber packing into a circular hole penetrating the bottom of the container wall of the container 6, and can easily supply hydrogen gas by external syringe injection. It has become.

  In addition, the supply port 12 may be configured by attaching a small check valve (used for a tire tube) or an open / close valve.

  The holding plate 7 has the same dimensions as the electrolyte membrane 2, and has a window 11 of the same size as the cathode 4.

  The container wall of the container 6 and the holding plate 7 are formed of an insulating plate having a strength suitable for fixing the unit cell 5 and the current collector plates 8 and 9 therebetween, and specific examples of the insulating plate. Examples thereof include a resin plate, a ceramic plate, and a metal plate coated with a non-conductive substance.

  Each of the current collector plates 8 and 9 is a copper plate (thickness: 0.5 mm) having substantially the same size as the electrolyte membrane 2, and has a central portion provided with a passage for supplying hydrogen gas and air to the anode 3 and the cathode 4. To ensure this, a window of a size slightly smaller than the anode 3 and the cathode 4 (for example, 4.5 cm × 4.5 cm) is opened.

  The reason why the window is made slightly smaller is that the anode 3 and the cathode 4 are brought into contact with the current collector plates 8 and 9 to conduct electricity.

  Although the entire window may be hollowed out, if the window has a structure in which a plurality of holes are formed in a mesh shape, the electrolyte membrane 2 will be sandwiched between the mesh portions. The strength against the differential pressure applied to the membrane 2 can be improved.

  One end of the current collector plate 8 extends slightly further outward than the side surface of the structure, and the extended portion is bent along the side surface to form a terminal electrode 8a (cathode terminal). I have.

  On the other hand, the current collector 9 extends on the side opposite to the terminal electrode 8a, and similarly has a terminal electrode 9a (anode terminal).

  Insulating plates 17 and 18 are interposed on the inner side surfaces of the terminal electrodes 8a and 9a to prevent the current collecting plates 8 and 9 from coming into contact with each other.

  O-rings 15 and 16 are interposed between the current collector plate 8 and the container 6 and the electrolyte membrane 2 to prevent leakage of the fuel gas, the anode 3 and the air.

In such a laminated body including the container 6, the current collector 8, the electrolyte membrane 2, the current collector 9, and the presser plate 7, the terminal electrodes 8a, 9a are exposed on the opposing side surfaces.
The pressure-bonding members 13 and 14 are U-shaped cross-sections that cover another opposing side surface of the laminate, and are elastic members having a strength such that the laminate can be pressed and fixed. In order to prevent a short circuit between the current collector plate 8 and the current collector plate 9, the pressure bonding members 13 and 14 may be formed of an insulating material such as resin or ceramics, or may be formed of a metal plate. It is desirable to arrange things.

  When the laminate is tightened by the pressure members 13 and 14, the outer periphery is sealed between the container 6, the current collector 8, the electrolyte membrane 2, the current collector 9 and the holding plate 7, but the fuel cell 1 By applying an adhesive filler such as silicone rubber to the outer periphery of each of the above members at the time of assembling, the sealing performance can be further improved.

  In the fuel cell 1 having such a configuration, outside air is supplied to the cathode 4 from the window 11, and hydrogen gas stored in the container 6 is supplied to the anode 3 from the window 10, and power is generated by an electrochemical reaction.

  Then, since the hydrogen gas in the container 6 is reduced due to the power generation and the pressure is reduced, the generated power is also reduced. However, when the generated power is reduced to a certain extent, the hydrogen can be regenerated by replenishing the supply port 12 with the hydrogen gas. Can be.

Therefore, the fuel cell 1 can be used as a secondary battery. When replenishing the container 6 with hydrogen gas, it is necessary to perform the process at a pressure within a range in which the electrolyte membrane 2 can withstand a differential pressure. However, if the windows of the current collectors 8 and 9 are meshed as described above, the pressure for replenishing hydrogen can be increased.

  In addition, if a hydrogen storage alloy is inserted into the inner space of the container 6 and hydrogen is stored therein, the amount of hydrogen gas stored can be increased. Can be.

  As described above, the fuel cell 1 does not require a manifold or a pump for supplying the fuel gas and the air, and can be easily used by itself. You can also.

  FIG. 4 is an external view of an assembled battery 20 including the plurality of fuel cells 1 described above.

  The assembled battery 20 has a configuration in which an appropriate number (for example, 20) of the fuel cells 1 are arranged in a matrix (5 rows × 4 columns) in a square insulating frame 21 in a plane. ing.

  The cathode terminals 8a and the anode terminals 9a of the adjacent batteries 1 are arranged so as to be in contact with each other. The terminals at the ends of each row are electrically connected in series by a conductive plate 22 provided on the side surface of the frame 21. , All the fuel cells 1 are electrically connected in series. Then, it is output to the outside by lead wires 23 provided on the frame body 21.

  FIG. 5 is a cutaway view of the assembled battery 20 taken along the line Y-Y. The connection specifications of the fuel cells 1 in the assembled battery 20 are indicated by arrows. The direction of the arrow indicates the direction from the anode to the cathode.

  A desired voltage can be obtained by arranging the fuel cells 1 to form the assembled battery 20 in this manner.

  Here, the fuel cell 1 has a rectangular columnar structure, but it may be formed in a columnar shape or a regular polygonal shape (other than a square shape).

  Further, in the fuel cell 1, the laminate is pressed and fixed using the pressing members 13 and 14 made of an elastic material. As another fixing method, for example, the container 6 and the holding plate 7 are formed in a flange shape. Alternatively, both members may be fixed with screws.

  The fuel cell 30 according to the second embodiment has the same configuration as that of the fuel cell 1 according to the first embodiment except for the structure of the holding plate 7.

  FIG. 6 is an external perspective view of the fuel cell 30.

  As shown in FIG. 6, the holding plate 31 of the fuel cell 30 is the same as the holding plate 7 of the first embodiment, except that in addition to the window 31a for introducing air, auxiliary air holes 31b (in FIG. Holes are shown.). The auxiliary air holes 31b are provided in parallel with the main surface of the holding plate 7 so as to penetrate between the side surface and the window 31a.

  FIG. 7A is a cross-sectional view of the fuel cell 30 of the second embodiment, and FIG. 7B is a cross-sectional view of the fuel cell 1 of the first embodiment. The operation of providing the auxiliary air holes will be described with reference to these drawings.

  In the fuel cell 30 having the auxiliary air holes, outside air flows into the windows 31a through the auxiliary air holes 31b and is supplied to the cathode 4 as shown by the white arrows in FIG.

  Then, the warm air used for power generation at the cathode 4 rises through the window 31a as indicated by a diagonal arrow and is discharged into the outside air.

  In this way, a smooth air flow due to natural convection is generated in the direction of the auxiliary air hole → the cathode → the window → the upper part of the holding plate →... And the air supply to the cathode is promoted.

  On the other hand, in the fuel cell 1 in which the auxiliary air hole is not opened, the air heated by the cathode 4 rises from the window and is discharged into the outside air (see FIG. 7B), but the outside air flows. Since the passage has only this window, the smooth air flow as described above does not occur. Therefore, the supply of air to the cathode is not sufficient.

  By providing the auxiliary air holes 31b in this manner, the supply of air to the cathode is promoted, so that it is possible to suppress a voltage drop when power is generated at a high current density.

The larger the opening area of the auxiliary air hole 31b is, the more the inflow of air is increased.
<Experiment 1>
The following experiment was conducted to examine the effect of the auxiliary air holes.

-Experimental method Platinum-supporting carbon, Teflon (registered trademark) as a binder, and calcium carbonate as a pore-forming agent were mixed, filtered, rolled and formed into a sheet, and then immersed in 1N nitric acid. The pore former was removed to prepare a porous electrode sheet.

  A single cell was prepared by sandwiching a polymer electrolyte membrane (Nafion manufactured by DuPont) having a thickness of 20 μm with the above-mentioned electrode sheet, and further hot-pressing the sandwiched with carbon paper.

Then, using this single cell, a fuel cell was assembled based on the fuel cell 30 described above. Here, the holding plate 31 was 8 cm long, 5 cm wide and 1 cm thick, the size of the window 31 a was fixed at 5 cm ² , and the total cross-sectional area of the auxiliary air holes 31 b was variously changed. .

The total cross-sectional area of the auxiliary air holes 31b formed in the holding plate 31 is 0.628 cm ² , 0.251 cm by setting the number of circular holes having a cross-sectional area of 0.0314 cm ² to 20, 8, and 4. ² , set to 0.126 cm ² .

  The fuel cells assembled in this manner were referred to as cells A, B, and C. Further, a fuel cell having no auxiliary air holes was also assembled as cell D.

With respect to the batteries A to D produced in this manner, hydrogen gas was continuously supplied from the supply port of the container 6, and power was generated while maintaining the inside at normal pressure. Then, the voltage was measured while changing the current density (mA / cm ² ).

Experimental Results and Discussion Table 1 shows the cell voltage (mV) of each battery at a current density of 200 mA / cm ² . The ratio (%) of the area of the auxiliary air hole to the area of the window of each battery is also shown.

図８は、各電池Ａ〜Ｄについて電流密度に対するセル電圧をプロットした特性図である。

FIG. 8 is a characteristic diagram in which the cell voltage with respect to the current density is plotted for each of the batteries A to D.

  As shown in this figure, in any of the batteries, the cell voltage decreases as the current density increases, but the larger the ratio of the opening area of the auxiliary air holes to the opening area of the air window, the higher the current density, The voltage drop is small.

  It can be said that the larger the ratio, the larger the amount of air flowing into the air window.

  The fuel cell 40 according to the third embodiment has the same configuration as that of the first embodiment, except that an opening / closing lid is provided on a window of the holding plate.

  FIG. 9 is an external perspective view of the fuel cell 40.

  The fuel cell 40 is provided with an openable / closable lid 41 that covers the window 42 of the holding plate 43. When the battery is not used, the lid 41 is closed to shut off the cathode from the outside air. By removing the lid 41 by hand, the cathode is opened to the outside air.

  The opening / closing lid 41 includes a flat plate portion 41a having a size slightly larger than the window 42, and a protruding portion 41b protruding from the center of one surface of the flat plate portion 41a.

  The projecting portion 41b is formed to have a slightly smaller dimension than the window 42, and the opening / closing lid 41 can be fixed by inserting the projecting portion 41b into the window 42.

  By closing the window 42 with the opening / closing lid 41 during storage of the battery in this way, it is possible to prevent the electrolyte membrane from drying during storage of the battery, and to exhibit the performance of the battery immediately after the operation of the battery is started.

  Further, by providing the opening / closing lid 41 in this manner, the electrode surface can be physically protected.

  In the third embodiment, the opening / closing lid 41 can be removed. However, the opening / closing lid 41 is pivotally mounted on the upper surface of the holding plate 43, and the opening / closing lid 41 is rotated to open and close the window 42. You may do so.

  Alternatively, the opening / closing lid 41 consisting of only the flat plate portion 41a may be slidably mounted along the upper surface of the holding plate without providing the convex portion 41b, and the window 42 may be opened / closed by sliding the opening / closing lid 41. Good.

Further, an automatic opening / closing mechanism may be attached to such an opening / closing lid, so that the opening / closing lid is opened when the fuel cell 40 is loaded in the equipment to be used, and is closed when the fuel cell 40 is removed from the equipment to be used.
<Experiment 2>
-Method of experiment In this experiment, a battery similar to the battery D used in the above experiment 1 was used except that an opening / closing lid for covering the window of the holding plate was provided. After storage for 3 days, the lid was opened to generate power at a current density of 100 mA / cm ² . Then, the voltage (mV) and the internal resistance (Ω · cm ² ) of each operation time (min.) Were measured. As a comparative example, the same measurement was performed after storing for 3 days without opening and closing the lid.

  The supply of hydrogen gas to the container was performed in the same manner as in Experiment 1.

Experimental Results and Discussion FIG. 10 is a table showing the measurement results, and FIGS. 11 and 12 are characteristic diagrams created based on the measurement results.

  As shown in FIGS. 10 to 12, in the battery stored with the lid open and closed, 80% or more of the maximum voltage can be obtained in one minute from the start of the battery, and the maximum voltage can be obtained almost three minutes later. The level reached almost the same as the maximum voltage and resistance of the battery immediately after the fabrication of the battery.

  On the other hand, when stored without opening and closing the lid, the maximum voltage was not reached until 10 minutes or more had elapsed from the start, and the maximum voltage in this case was 93% lower than immediately after the production. Further, the internal resistance value reached 150% immediately after fabrication.

  Thus, it can be seen that if the window for air introduction is closed by the open / close lid when the battery is stored, the battery can exhibit the initial performance immediately after the battery operation starts even after the battery storage.

  In this experiment, the storage period was three days, but the longer the storage period, the more noticeable the difference between the case with and without the open / close lid.

  FIG. 13 is a perspective view of the fuel cell according to the fourth embodiment.

  The fuel cell 50 according to the fourth embodiment has the same configuration as the fuel cell 30 according to the second embodiment, except that a clip-shaped auxiliary lid 53 that can close the auxiliary air hole 52 of the holding plate 51 is provided. Although not shown, the window 54 of the holding plate 51 can be closed by an opening / closing lid similar to the opening / closing lid 41 of the third embodiment.

  The auxiliary lid 53 has a U-shaped cross section, and is inserted into a side surface of the battery 50 where the auxiliary air hole 52 is opened.

  A notch 53a is formed on the inner wall surface of the auxiliary lid 53 so that the electrode terminal can be fitted therein.

  The auxiliary lid 53 also serves to press the battery stack in the stacking direction (the direction indicated by the black arrow in the drawing).

  In such a fuel cell 50, the window 54 and the auxiliary air hole 52 are closed by the opening / closing lid and the auxiliary lid 53 when not in use, and the opening / closing lid and the auxiliary lid 53 are removed when in use. Can be obtained.

  In the fourth embodiment, the auxiliary lid 53 for closing the auxiliary air hole 52 is provided. If the auxiliary air hole 52 is closed by the portion, both the window 54 and the auxiliary air hole 52 can be closed only by the opening / closing lid without using the auxiliary lid 53.

Further, as in the case of the third embodiment, such an opening / closing lid can be pivotally attached to the holding plate, or an automatic opening / closing mechanism can be attached.
[Other matters]
In each of the above embodiments, the case of the polymer electrolyte fuel cell has been described. However, it is needless to say that the present invention is similarly applied to a fuel cell of a phosphoric acid type, an alkaline type, or the like that operates at a low temperature. be able to.

FIG. 2 is an assembly diagram of the fuel cell 1 according to the first embodiment. FIG. 1 is an external perspective view of a fuel cell 1 according to a first embodiment. FIG. 3 is a sectional view taken along line XX of the fuel cell 1 shown in FIG. 2. FIG. 2 is an external view of an assembled battery 20 including a plurality of fuel cells 1. FIG. 5 is a sectional view taken along line YY of the battery pack 20 shown in FIG. 4. FIG. 7 is an external view of a fuel cell 30 according to a second embodiment. FIG. 6 is a diagram illustrating the flow of air during operation of the batteries of Example 2 and Example 1. FIG. 4 is a characteristic diagram illustrating a relationship between a cell voltage and a current density. FIG. 13 is an external perspective view of a fuel cell 40 according to a third embodiment. 9 is a table showing the results of a storage experiment. FIG. 9 is a characteristic diagram showing a result of a storage experiment. FIG. 9 is a characteristic diagram showing a result of a storage experiment. FIG. 10 is an external perspective view of a fuel cell 50 according to a fourth embodiment. FIG. 9 is an exploded perspective view showing an example of a conventional compact fuel cell.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Electrolyte membrane 3 Anode 4 Cathode 5 Cell 6 Container 7 Holder plate 8, 9 Current collector plate 8a, 9a Terminal electrode 10, 11 Window 12 Supply port 13, 14 Crimping member 15, 16 O-ring 17, 18 Insulating plate

Claims (4)

A fuel cell comprising: a cell in which an electrolyte membrane is sandwiched between an anode and a cathode; an anode-side plate member and a cathode-side plate member that sandwich and fix the cell; and a fuel storage container that stores fuel supplied to the anode. ,
A fuel cell, wherein the fuel storage container is disposed on the anode side of the cell, and a fuel supply port for supplying fuel to the anode is provided on a wall surface of the fuel storage container.   The fuel cell according to claim 1, wherein the wall surface and the anode-side plate are shared.   The fuel cell according to claim 1, wherein the cathode-side plate includes an oxidant supply port that supplies an oxidant to the cathode. 4. The fuel cell according to claim 3, wherein the oxidant supply port is openable and closable by an opening / closing lid.

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