JP2001283888A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell which is particularly useful for a power source of small electric equipment and suitable for a small thin type battery cell that is improved in reliability for taking out the battery power for a long time stably and efficiently by preventing in particular leakage of liquid fuel. SOLUTION: The fuel cell comprises a fuel electrode, an oxidant electrode disposed opposed to the fuel electrode, an electrolyte layer held by the fuel electrode and the oxidant electrode in between, and a liquid fuel holding portion which holds liquid fuel and supplies continuously the liquid fuel to the fuel electrode. A fuel leakage preventive membrane is installed at least at the side of the fuel electrode for preventing the leakage of fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell, and more particularly to a fuel cell suitable for miniaturization.

2. Description of the Related Art In recent years, fuel cells have attracted attention because they are efficiently advantageous as a single power generator. Fuel cells include a phosphoric acid type fuel cell using gas as fuel, a molten carbonate type fuel cell, a solid electrolyte type fuel cell, an alkaline electrolyte type fuel cell, etc., and a methanol fuel cell using liquid as fuel. And hydrazine fuel cells. Each of these fuel cells
Since it mainly targets power generators and power sources for operating large equipment, compressors and pumps for introducing gas or liquid fuel or oxidizing gas into the battery are required. As well as consume power for these introductions.

On the other hand, a liquid fuel cell utilizing capillary force to supply liquid fuel has been proposed as a fuel cell in which additional auxiliary devices are reduced to cope with miniaturization.
-66066 and JP-A-6-188008. In these liquid fuel cells, liquid fuel is supplied from a fuel container to a fuel electrode by capillary force.
There is no need for a pump for pumping the liquid fuel required for the liquid supply type fuel cell.

[0003] Here, a small or thin fuel cell is often used by being enclosed in a metal can or the like in order to maintain its mechanical strength. Also, methanol, which is a liquid fuel, may not be fully reformed on the fuel electrode side, and therefore, the liquid fuel leaks or leaches to the outside in a liquid state, and travels along the side surface of the electromotive unit, etc. There is a problem of doing. Such leakage of fuel becomes a factor that hinders stabilization of the output characteristics of the battery. In particular, according to the findings of the present inventor, it has been found that liquid fuel leaching to the oxidant electrode side through the side surface of the fuel electrode or the interface portion thereof is an important factor that hinders stabilization of output characteristics. are doing.

Conventionally, there has been proposed a method of mechanically maintaining the airtightness of a liquid fuel with a member such as a fastening jig. However, the prevention of the leakage by fastening a metal member or the like becomes structurally complicated. This is disadvantageous in terms of battery size and cost. Further, the prevention of leakage by the fastening means is not always effective, and there is a problem of re-leakage. Further, at present, it cannot be said that leakage of liquid fuel at the molecular level is sufficient.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the conventional fuel cell, and
It is useful as a power source for small electric equipment, and it has particularly improved the reliability of effectively eliminating the problem of liquid fuel leakage and stably and efficiently extracting battery output for a long time. -It is an object to provide a fuel cell particularly suitable for a thin battery.

[0006]

According to the present invention, there is provided a fuel cell comprising: a fuel electrode; an oxidant electrode disposed to face the fuel electrode; an electrolyte layer sandwiched between the fuel electrode and the oxidant electrode; A liquid fuel holding portion that holds a liquid fuel and can continuously supply the liquid fuel to the fuel electrode, and at least on a side surface of the fuel electrode, to prevent leakage of the liquid fuel. A fuel leakage prevention film is provided.

In a preferred embodiment of the present invention, the fuel leakage prevention film is formed on the surface of the fuel electrode, and / or the surface and / or side surface of the liquid fuel holding portion, and / or the fuel electrode and the electrolyte layer. At least a part of the interface portion between them is provided so as to cover these components.

Further, in a preferred aspect of the present invention, the fuel leakage prevention film is held at a fusion state to such an extent that the liquid fuel does not leach at the interface of the coating portion.

In the present invention, the fuel leakage prevention film used in the fuel cell may have a laminated structure in which a metal layer is sandwiched between organic layers.

Further, the above-mentioned fuel leakage prevention film is preferably made of a material having electrical insulation, chemical resistance, moisture proof and heat release characteristics, and plastic deformation.

In another aspect of the present invention, a fuel supply hole for supplying fuel to a fuel electrode side of a fuel cell is provided with one fuel supply hole.
Alternatively, two or more fuel supply holes may be provided so that the fuel supply holes can be sealed after fuel supply.

Further, in the present invention, a generated gas discharge port may be provided on a fuel leakage prevention film provided on a fuel electrode of a fuel cell.

In the fuel cell of the present invention, one or more oxidant supply holes for supplying air and / or oxygen as an oxidant may be provided on the cathode side of the fuel cell.

Further, in the present invention, a liquid / gas separation membrane for releasing generated water may be provided on the cathode side of the fuel cell.

Further, in another aspect of the fuel cell of the present invention, the fuel cell further comprises a fuel tank for storing a liquid fuel, wherein the fuel tank is included in the inside of the cell body and the liquid fuel is stored. The fuel tank further includes a fuel tank, and the fuel tank is externally provided outside the battery body.

Further, in a preferred embodiment, the apparatus further comprises a fuel tank for storing a liquid fuel, even if the fuel tank is coated with a metal material.

Further, in the present invention, the fuel cell is constituted by a plurality of divided unit cells, and each unit cell is sealed with a liquid and a gas by fusing a fuel leakage prevention film, and each cell is connected to an external lead. It may be electrically connected.

Further, another aspect of the present invention includes a configuration in which the fuel tank is sandwiched between a pair of unit cells, or a configuration in which the fuel tank is provided on the outer periphery of the battery.

Further, in the fuel cell according to the present invention, the fuel tank may be built in the main body of the device that requires power generation.

Further, in the fuel cell of the present invention, the fuel passage is opened by bending the fuel tank,
Thereby, the fuel may be supplied to the battery.

Further, in the present invention, by closing the lid of the battery storage cartridge, the fuel tank incorporated in the battery main body and the battery may be electrically connected to generate power.

Still another embodiment of the present invention includes a configuration in which a voltage terminal of a fuel cell is covered with a fuel leakage prevention film.

The present invention includes a hybrid fuel cell in which the above-described fuel cell and secondary battery are combined and integrated.

Further, in a preferred embodiment of the present invention, a heat insulating material is further provided on the outer periphery of the electromotive section of the fuel cell. As such a heat insulator, its thermal conductivity,
The range of 5 × 10 ⁻³ W / mK to 10 W / mK is preferable, and the porosity of the heat insulating material is preferably in the range of 10% to 95%.

In the present invention, the provision of the above-described fuel leakage prevention film can effectively and easily prevent leakage or leaching of liquid fuel. In addition, since it is not necessary to mechanically maintain the airtightness for preventing fuel leakage using a fastening jig or the like, the structure is simple, and it is extremely advantageous in reducing the size and thickness. In addition, since there is no structural limitation, the effective area of the electromotive section can be effectively used 100%, which is advantageous in terms of electromotive efficiency.

Further, in a preferred embodiment of the present invention, by providing a heat insulating material on the outer periphery of the electromotive portion, the reaction heat of the battery reaction is confined inside without dissipating the heat to the outside, so that power can be efficiently generated even near room temperature. Electromotive section (fuel electrode, oxidizer electrode and electrolyte sandwiched between them)
By providing a heat insulating material having the optimum thermal conductivity and porosity on the outer periphery of the device, it is possible to take out a stable output for a long time.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to preferred embodiments.

As shown in the sectional view of FIG. 1, the fuel cell according to the present invention comprises a fuel electrode 1, an oxidant electrode 2 disposed opposite to the fuel electrode 1, an anode 1 and an oxidant electrode 2. And a liquid fuel holding portion 4 for holding the liquid fuel and continuously supplying the liquid fuel to the fuel electrode 1. The fuel electrode 1, the liquid fuel A fuel leakage prevention film 5 for preventing liquid fuel from leaking at the holding portion 4 and at the interface between the fuel electrode 1 and the electrolyte layer 3
Is provided. Reference numeral 7 in FIG. 1 denotes a fuel tank.

In the case of the fuel cell according to the present invention, the porous substrate constituting each electrode may be carbon paper, carbon molded body, carbon sintered body, sintered metal, foamed metal, both positive and negative. Such a porous substrate can be used after being subjected to a water-repellent treatment. In this case, polytetrafluoroethylene or the like can be used as a water-repellent agent.

As a material of the fuel electrode 1, fine powder of noble metal such as platinum, platinum alloy, gold, gold alloy, palladium, palladium alloy or carbon powder carrying noble metal can be used as the noble metal catalyst. Preferably, a mixture of platinum and ruthenium can be used.

The oxidizer electrode 2 may be a noble metal catalyst such as a fine powder of a noble metal such as platinum, a platinum alloy, gold, a gold alloy, palladium, or a palladium alloy, or a carbon powder carrying a noble metal.

These porous electrodes can be produced by applying a catalyst dispersion to the surface of a porous substrate that has been subjected to a water-repellent treatment. The catalyst dispersion solution in this case can be prepared by uniformly mixing fine particles of a catalyst such as platinum black and a solid polymer electrolyte dissolved in an alcohol or the like in an appropriate solvent.

As the electrolyte layer 3, usually, a perfluorosulfonic acid film, a polybenzimidazole film or the like is preferably used.

The porous electrode having the catalyst layer formed thereon and the solid polymer electrolyte membrane can be joined and integrated by a method such as hot pressing.

Further, as the liquid fuel holding section 4, a porous organic material such as polyester and polyolefin, a porous inorganic material such as carbon and alumina, and a porous material such as a net-like metal porous material can be appropriately used.

In a preferred embodiment of the present invention, the fuel leakage prevention film 5 has at least one of the surface and side surface of the fuel electrode 1, the surface of the liquid fuel holding unit 4, and the interface between the fuel electrode 1 and the electrolyte layer 3. Is provided so as to cover the components, and to cover these components, and these components and the fuel leakage prevention film 5 are in a fused state such that the liquid fuel does not leach at the interface between them. Will be held.
FIG. 9 is a cross-sectional view of the fuel cell as viewed from the side, and is an example of a mode in which a fusion portion 6 is formed at a portion where the external lead 20 is provided.

As shown in the sectional view of FIG. 1, a fused portion 6 is formed inside the fuel leakage prevention film 5. By forming the fused portion at the interface between the component and the component to be coated, leaching of the liquid fuel at the molecular level can be effectively prevented. Such a fused portion can be formed by heat fusion.

The fuel leakage prevention film 5 used in the present invention has, for example, a sheet shape and forms an exterior of a sheet battery. The exterior member may be formed of a single material, or may be formed of a plurality of materials. Further, it may have a single-layer structure or a multilayer structure.

Specifically, as the fuel leakage prevention film, a material having electrical insulation, chemical resistance, moisture proofness, heat release characteristics, and plastic deformation can be preferably used.
Preferred examples of the fuel leakage prevention film material include an epoxy resin, a polyester resin, a polyamide resin, an acrylic resin, a polyimide resin, a polybenzimidazole resin, an olefin resin, a furan resin, and a silicone resin.

Further, a preferable example of the fuel leakage prevention film is a multilayer structure comprising a protective layer containing a resin material, a metal layer containing a metal material, and an adhesive layer containing an adhesive if necessary. And the like. By configuring the exterior member with a multilayer structure as described above, resistance to external damage can be improved, and moisture resistance can be further improved. In particular, by including a metal layer in the multilayer structure, the moisture-proof effect is significantly improved.

In the above-mentioned preferred structure, preferred materials for forming the protective layer include films of polyester, nylon, polycarbonate, polyacrylate, liquid crystal polyester, polyphenylene sulfide, polysulfone, polyether ether ketone and the like.
In addition, as a material for forming the metal layer, aluminum,
Metal foils such as copper and stainless steel are exemplified. Aluminum foil is particularly preferred in terms of barrier properties and plasticity.

Examples of the material for forming the adhesive layer include olefins such as ethylene vinyl acetate copolymer (EVA), ethylene acrylic acid copolymer (EAA), ethylene ethyl acrylate copolymer (EEA), and modified polypropylene resin. Hot melt adhesives are preferred examples.

The thickness of the fuel leakage prevention film may be set to about 60 μm to 300 μm irrespective of its structure. The thickness of the exterior member may be different between one and the other. When the fuel leakage prevention film is a laminate including the above-described protective layer, metal layer, and adhesive layer, the protective layer is about 10 μm to 100 μm, and the metal layer is about 15 μm.
about 100 μm, adhesive layer 30 μm to 100 μm
m is preferable.

Hereinafter, various aspects of the present invention will be described.

In the fuel cell shown in the plan view of FIG.
A terminal 20 is connected to the battery body, and a fuel leakage prevention film 21 is laminated so as to cover the outer periphery of the battery body. In this embodiment, a fuel supply hole 22 for supplying fuel to the fuel electrode side of the fuel cell is provided, and the fuel supply hole is formed so as to be able to be sealed after fuel supply.
Further, in this example, a generated gas discharge port 23 for discharging a generated gas generated as a recovery gas is also formed.

In the embodiment shown in FIG. 3, the fuel leakage prevention film 2
1 and an oxidant supply hole 24 for supplying air and / or oxygen as an oxidant to the cathode side of the fuel cell. Further, in the embodiment shown in FIG. 3, a liquid / gas separation membrane 25 for discharging generated water (a region surrounded by a broken line) may be provided on the cathode side of the fuel cell.

In the embodiment shown in FIG. 4, a fuel tank 40 for storing liquid fuel is provided inside a battery main body together with an electromotive section 41.

In the embodiment shown in FIG. 5, a fuel tank 40 is externally provided outside the battery body A. The fuel cell according to claim 1. In this case, the fuel tank 40 may be covered with a metal material in order to maintain mechanical strength.

Further, in the fuel cell of the present invention, the fuel cell is constituted by a plurality of divided unit cells,
Each unit cell is liquid by fusing a fuel leakage prevention membrane,
The cells may be gas-sealed and electrically connected by external leads.

In the present invention, the fuel tank is
It also includes a configuration sandwiched between a pair of unit cells, a configuration in which a fuel tank is provided on the outer periphery of the battery, and a configuration in which the fuel tank is built in an apparatus body that requires power generation.

In still another embodiment, the fuel passage may be opened by bending a fuel tank attached to the fuel cell, whereby fuel may be supplied to the cell. Further, in another preferred embodiment, by closing the lid of the battery storage cartridge, the fuel tank and the battery incorporated in the battery main body are electrically connected to each other so that power can be generated. You may.

Further, at least a part of the voltage terminals of the fuel cell may be covered with the above-described fuel leakage prevention film.

Although the fuel cell of the present invention can be used alone as a cell, in another embodiment of the present invention,
It is also possible to combine the fuel cell according to the present invention with another secondary battery and apply it as a hybrid fuel cell.

FIG. 6 is a sectional view showing another embodiment of the fuel cell of the present invention. In the figure, 61 is a fuel permeable layer, 6
2 is a heat insulating material, 63 is a fuel vaporizing section, 64 is a fuel electrode, 65 is an electrolyte, 66 is an oxidant electrode, 67 is an oxidant gas flow path, 6
Reference numeral 8 denotes a seal member for preventing fuel and oxidant gas from volatilizing to the outside, and reference numeral 69 denotes a storage container for storing a fuel cell for the purpose of protecting the electromotive section and the like. Also in this embodiment, a fuel leakage prevention film (not shown) is formed at the above-mentioned predetermined location.

This embodiment will be described specifically, including the power generation mechanism. First, liquid fuel is supplied to the fuel permeable layer 61 from the outside. The liquid fuel can be supplied by simply providing one or a plurality of holes in the container 69 as shown in FIG. 6 and directly supplying it from there, or as shown in FIG. It is also possible to prepare the storage container 72 and draw it from there using the capillary force of the fuel permeable layer 61. As the fuel permeable material 61, any material such as a porous organic material such as polyester and polyolefin, a porous inorganic material such as carbon and alumina, and a mesh-like porous metal material is acceptable. The fuel supplied to the fuel infiltration layer 61 is evaporated in the fuel vaporization section 3 and supplied to the electromotive section (the fuel electrode 64, the electrolyte 65, and the oxidant electrode 66) in the form of a gas. It should be noted that, as the vaporizing portion, a certain kind of material (a porous material similar to the above-described fuel-penetrating material) may be physically present, or the fuel-penetrating material may be used only in a space having only holes. It is. The vaporized liquid fuel supplied to the fuel electrode 64 is reformed by a fuel cell catalyst typified by platinum or an alloy thereof supported on carbon particles inside the fuel electrode formed of carbon particles. Taken out. Electrons are extracted during the fuel reforming. The extracted protons are transmitted to the oxidant electrode 6 through an electrolyte 65 provided adjacently. On the other hand, on the oxidant electrode 66 side, protons selected through the electrolyte 65 flow through an external circuit,
The reaction with the oxidant gas (eg, oxygen or air) to form water proceeds on a catalyst typified by platinum or the like inside the oxidant electrode. The electrons taken out in the course of the reaction as described above flow through an external circuit to generate power, which can drive an external load.

At the time of this power generation, as described above,
Reaction heat is generated when the vaporized liquid fuel supplied to 4 is reformed by the catalyst. This heat raises the temperature of the fuel electrode 64, thereby increasing the activity of the catalyst and making it possible to easily obtain a high output. For this reason, in the small fuel cell shown in FIG. 6, the heat insulating material 62 is provided outside the fuel permeable layer 61 and outside the oxidizing gas channel 67 in order to effectively use the reaction heat. The provision of the heat insulating material 62 has an effect of preventing the reaction heat from volatilizing to the outside. This makes it possible to continuously take out a stable output.

As a preferable material of such a heat insulating material, any of organic, inorganic, metal and composite materials thereof can be used. Further, the same material or the different material can be used for the fuel electrode side and the oxidizer electrode side. Since it is a member provided to confine the reaction heat inside, it is desirable that its thermal conductivity be low.
K, more preferably 1 W / mK or less. On the other hand, if a material having a thermal conductivity lower than 5 × 10 ⁻³ W / mK is used, the temperature of the power generation unit rises remarkably, making it difficult to control and causing a problem in stable power generation. More preferably 1
× 10 ⁻² W / mK or more.

In a preferred embodiment of the present invention,
The above-described fuel leakage prevention film for preventing leakage of the liquid fuel at the fuel electrode, the liquid permeable layer, the fuel vaporization layer, and the interface between the fuel electrode and the electrolyte layer may be provided. Such a fuel leakage prevention film is provided so as to cover these components on at least a part of the surface or side surface of the fuel electrode, the surface of the liquid permeable layer, and the interface between the fuel electrode and the electrolyte layer. It is particularly preferable that these constituent members and the fuel leakage prevention film are maintained in a fused state at such an interface that the liquid fuel does not leach out.

[0059]

Next, specific examples of the fuel cell of the present invention will be described in detail with reference to production examples. In addition, the following examples are shown for easy understanding of the contents, and do not limit the scope of the present invention.

Example 1 A small fuel cell shown in FIG. 1 was manufactured according to the following procedure. First, external shape 100mmx8
0 mm, a polyester film having a thickness of 16 μm, and an aluminum metal foil having the same outer shape as described above and a thickness of 20 μm were bonded to each other by a dry lamination method using a urethane-based adhesive. A fuel-leakage prevention film 5 formed by bonding a hot-melt adhesive made of an ethylene-vinyl acetate copolymer (EVA) into a film in advance so as to have a thickness of 0.050 mm with the adhesive.
Was prepared.

The laminated body to be accommodated was composed of the EMA in which the fuel electrode, the oxidant electrode and the electrolyte layer were joined, the liquid fuel holding part, and the fuel tank, and was manufactured so as to have a total thickness of 2 mm.

This EMA was produced by the following procedure. Ma
, Pt-Ru catalyst supported on carbon powder by liquid phase method
I let it. After collecting this carbon powder, an argon-hydrogen gas
The catalyst was stabilized by firing in a stream. Next, this catalyst powder
Add a solvent and a binder at the end to make a paste,
Apply it on the bon cloth and dry it to form the catalyst layer on the fuel electrode side.
Formed. Separately, carbon powder carrying a Pt-based catalyst
The powder is made in the same process as the fuel electrode side,
Add binder and paste to make carbon cloth
And dried. Fuel electrode fabricated in this way
And the oxidizer electrode are cut into 40 mm x 50 mm, respectively, and the membrane
200 μm thick electrolyte membrane (perfluorosulfonic acid
Membrane). These are treated at 135 ° C. for 15 minutes for 10 minutes.
0kg / cm ² Hot pressing with pressure of 1 to integrate
Thus, MEA was obtained.

The fuel electrode has an oval cross section (width 3).
mm, a thickness of 100 μm), a length of 100 mm, and a lead terminal made of aluminum. The oxidizer electrode has an oval cross section (width 4 mm, thickness 50 μm) and length 100
mm, connected to lead terminals made of nickel.

In this manufacturing example, the heat sealing is performed at a position 10 mm inward from the outer periphery of the exterior member.

As a liquid fuel, a 1: 1 (weight ratio) mixture of methanol and water was supplied to the fuel permeable layer from the fuel supply hole formed on the fuel electrode side of the sealed container of the small fuel cell thus obtained. . The oxidizing gas was supplied by natural diffusion from a plurality of air intake holes provided in the container on the oxidizing gas side. FIG. 8 shows voltage characteristics of the battery when current was taken out at 0.2 A. A stable voltage was maintained even after about 8 hours had passed, confirming that a highly reliable small fuel cell was fabricated.

Example 2 A small fuel cell having the structure shown in the sectional view of FIG. 6 was manufactured according to the following method.

First, Pt-Ru was added to carbon powder by a liquid phase method.
The system catalyst was loaded. After recovering the carbon powder, it was calcined in an argon-hydrogen stream to stabilize the catalyst.
Next, a solvent and a binder were added to the catalyst powder to form a paste, which was applied on a carbon cloth and dried to form a catalyst layer on the fuel electrode side. Separately, a carbon powder carrying a Pt-based catalyst was prepared by the same process as that for the fuel electrode side, and a solvent and a binder were added to form a paste, which was then applied to a carbon cloth and dried.

The fuel electrode and the oxidizer electrode prepared as described above were cut into 40 mm × 50 mm, respectively.
A 0 μm electrolyte membrane (perfluorosulfonic acid membrane) was sandwiched. 100 kg / c at 135 ° C. for 15 minutes
It was integrated by hot pressing at a pressure of m ² . This electromotive section, a carbon porous plate having an average pore diameter of 100 μm and a porosity of 70% as the fuel vaporizing section 3, and a carbon porous plate having an average pore diameter of 5 μm and a porosity of 40% as the fuel permeable layer 1 were formed by It was sandwiched by a dense carbon plate having an oxidizing gas channel 7 having a thickness of 2 mm and a width of 1 mm. A 1 mm-thick polyester plate having a porosity of 35% and a thermal conductivity of 17 × 10 ⁻² W / mK is installed as a heat insulating material 2 outside the fuel permeable layer 1 and the oxidizing gas channel 7, and the whole is an aluminum can container Enclosed.
A Ni foil was used for the electrode, and it was taken out from the carbon paper for each of the fuel electrode and the oxidant electrode from a gap provided in a part of the seal member.

As a liquid fuel, a 1: 1 (weight ratio) mixture of methanol and water was supplied to the fuel permeation layer from the fuel supply hole formed on the fuel electrode side of the sealed container of the small fuel cell thus obtained. . The oxidizing gas was supplied by natural diffusion from a plurality of air intake holes provided in the container on the oxidizing gas side. FIG. 8 shows voltage characteristics of the battery when current was taken out at 0.2 A. A stable voltage was maintained even after about 12 hours had passed, confirming that a highly reliable small fuel cell was fabricated.

(Comparative Example 1) A voltage change when an output was taken out in the same manner as in Example 1 was measured for a small fuel cell manufactured in the same manner as in Example 1 except that the fuel leakage prevention film was not provided. . FIG. 8 shows the result. A voltage drop was observed after about 6 hours as compared with Example 1.
It turned out that it was inferior to stability compared with.

Example 3 A small fuel cell having the structure shown in FIG. 7 was manufactured in the following manner.

First, Pt-Ru was added to carbon powder by a liquid phase method.
The system catalyst was supported. After recovering the carbon powder, it was calcined in an argon-hydrogen stream to stabilize the catalyst.
Next, a solvent and a binder were added to the catalyst powder to form a paste, which was applied on a carbon cloth and dried to form a catalyst layer on the fuel electrode side. Separately, a carbon powder carrying a Pt-based catalyst was prepared by the same process as that for the fuel electrode side, and a solvent and a binder were added to form a paste, which was then applied to a carbon cloth and dried. The fuel electrode and the oxidant electrode prepared as described above were cut into 40 mm × 50 mm, respectively, and an electrolyte membrane (perfluorosulfonic acid membrane) having a thickness of 200 μm was sandwiched. These are 135 ° C
For 15 minutes at a pressure of 100 kg / cm ² and integrated. A fuel permeable layer 61 (polyolefin) in which the two electromotive portions are arranged facing each other so that the fuel electrode side is common, and a number of holes having a diameter of 8 mm are provided as fuel vaporization portions 63 so as to be in contact with the two fuel electrodes. Board, thickness 2m
m). A Teflon (registered trademark) sheet provided with a large number of holes having a diameter of 5 mm is provided on the oxidant electrode side, and a porosity of 65% and a thermal conductivity of 4 × 10 ⁻² W / mK are further provided as a heat insulating material 62 on that side. A 1 mm thick polyester plate was installed and the whole was sealed in an aluminum can container. A Ni foil was used for the electrode, and it was taken out from the carbon paper for each of the fuel electrode and the oxidant electrode from a gap provided in a part of the seal member.

A 1: 1 (weight ratio) mixture of methanol and water was supplied from the fuel container provided outside the small fuel cell thus obtained by utilizing the capillary force of the fuel permeable layer.
The oxidizing gas was supplied by natural diffusion from a plurality of air intake holes provided in the container on the oxidizing gas side. 0. of this battery
As a result of extracting a current at 2 A, a stable voltage was maintained even after approximately 24 hours at a voltage of 0.65 V, and it was confirmed that a highly reliable small fuel cell was manufactured.

[0074]

As is clear from the results of the above-mentioned Examples and Comparative Examples, according to the present invention, the problem of liquid fuel leakage is effectively solved, and the battery output is stably and efficiently used for a long time. It is possible to provide a fuel cell that is particularly suitable for a small and thin battery with improved reliability that can be easily taken out.

[Brief description of the drawings]

FIG. 1 is a sectional view of a fuel cell according to an embodiment of the present invention.

FIG. 2 is a plan view of a fuel cell according to an embodiment of the present invention.

FIG. 3 is a plan view of a fuel cell according to an embodiment of the present invention.

FIG. 4 is a plan view of a fuel cell according to an embodiment of the present invention.

FIG. 5 is a plan view of a fuel cell according to an embodiment of the present invention.

FIG. 6 is a sectional view of a fuel cell according to an embodiment of the present invention.

FIG. 7 is a sectional view of a fuel cell according to an embodiment of the present invention.

FIG. 8 is a graph showing voltage characteristics of an example of the present invention and a comparative example.

FIG. 9 is a sectional view of a fuel cell according to an embodiment of the present invention.

[Description of Signs] 1 fuel electrode 2 oxidizer electrode 3 electrolyte layer 4 liquid fuel holding part 5 fuel leakage prevention film 6 fusion part 7 fuel tank 20 terminal (external lead) 22 fuel supply port 23 generated gas discharge port

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Tomimatsu Koga Toshiba-cho, Koyuki-ku, Kawasaki-shi, Kanagawa 1 Inside the Toshiba R & D Center (72) Inventor Yoshihiko Nakano, Yoshiyuki-ku, Kawasaki-shi, Kanagawa Komukai Toshiba 1 Inside Toshiba R & D Center (72) Inventor Masahiro Takashita 1 Komukai Toshiba-cho 1 Koyuki-ku, Kawasaki-shi, Kanagawa Toshiba R & D Center (72) Inventor Kazuhiro Yasuda In-house Toshiba Research and Development Center, Komukai Toshiba-cho, Kawasaki City, Kanagawa Prefecture (72) Inventor Hiroyasu Tsuno No. 1 Toshiba Research and Development Center, Komukai Toshiba-cho, Kawasaki City, Kanagawa Prefecture (72) Inventor Maki Yonezu 1 Toshiba-cho, Komukai-shi, Kochi-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba R & D Center (72) Inventor Shuji Hayase Toshiba Komukai, Kochi-ku, Kawasaki-shi, Kanagawa 1 Toshiba R & D Center (72) Inventor Hirohisa Miyamoto 1 Komukai Toshiba-cho, Koyuki-ku, Kawasaki-shi, Kanagawa 1 F-term in Toshiba R & D Center (Reference) 5H026 AA08 CX03 CX04 CX05 EE02 EE05 EE18 EE19 HH00 HH04 5H027 AA08

Claims (22)

[Claims] A fuel electrode; an oxidant electrode disposed opposite to the fuel electrode; an electrolyte layer sandwiched between the fuel electrode and the oxidant electrode; and a liquid fuel holding the fuel electrode. And a liquid fuel holding portion capable of continuously supplying the liquid fuel to the fuel electrode, wherein at least a side face of the fuel electrode is provided with a fuel leakage prevention film for preventing leakage of the liquid fuel. Characteristic fuel cell. 2. The fuel leakage prevention film according to claim 1, wherein the fuel leakage prevention film is provided on a front surface side of the fuel electrode and / or a front surface side and / or a side surface side of the liquid fuel holding portion, and / or between the fuel electrode and the electrolyte layer. The fuel cell according to claim 1, wherein the fuel cell extends so as to cover at least a part of the interface portion, and is provided so as to cover these constituent members. 3. The fuel cell according to claim 1, wherein the fuel leakage prevention film is held in a fusion state to such an extent that the liquid fuel does not leach at the interface of the covering portion. 4. A fuel leakage prevention film used in the fuel cell,
Having a laminated structure in which a metal layer is sandwiched by organic layers,
The fuel cell according to claim 1. 5. The fuel cell according to claim 1, wherein the fuel leakage prevention film has electrical insulation properties, chemical resistance, moisture proofness, heat release characteristics, and plastic deformation properties. 6. The fuel cell according to claim 1, wherein one or more fuel supply holes for supplying fuel are provided on the fuel electrode side of the fuel cell, and the fuel supply hole is formed so as to be able to be sealed after fuel supply. A fuel cell according to claim 1. 7. The fuel cell according to claim 1, wherein a generated gas discharge port is provided on a fuel leakage prevention film provided on a fuel electrode of the fuel cell. 8. The fuel according to claim 1, wherein one or more oxidant supply holes for supplying air and / or oxygen as an oxidant are provided on the oxidant electrode side of the fuel cell. battery. 9. The fuel cell according to claim 1, wherein a liquid / gas separation membrane for releasing generated water is provided on the oxidant electrode side of the fuel cell. 10. The fuel cell according to claim 1, further comprising a fuel tank for storing the liquid fuel, wherein the fuel tank is included in a cell body. 11. The fuel cell according to claim 1, further comprising a fuel tank for storing the liquid fuel, wherein the fuel tank is externally provided outside the cell body. 12. The fuel cell according to claim 1, further comprising a fuel tank for storing the liquid fuel, wherein the fuel tank is coated with a metal material. 13. The fuel cell is composed of a plurality of divided unit cells, each unit cell is sealed by liquid and gas by fusing a fuel leakage prevention film, and each cell is electrically connected by an external lead. The fuel cell according to claim 1, wherein: 14. The fuel cell according to claim 1, wherein the fuel tank is sandwiched between a pair of unit cells. 15. The fuel cell according to claim 1, wherein a fuel tank is provided on an outer periphery of the cell. 16. The fuel cell according to claim 1, wherein the fuel tank is built in a main body of the device requiring power generation. 17. The fuel cell according to claim 1, wherein a fuel flow path is opened by bending the fuel tank, whereby fuel is supplied to the cell. 18. The fuel cell according to claim 1, wherein by closing a lid of the battery storage cartridge, a fuel tank built in the battery main body and the battery are electrically connected to generate power. . 19. The fuel cell according to claim 1, wherein a voltage terminal of the fuel cell is covered with a fuel leakage prevention film. 20. The fuel cell according to claim 1, wherein a heat insulating material is provided on an outer periphery of the electromotive section of the fuel cell. 21. A thermal conductivity of the heat insulating material is 5 × 10 ^−3.
21. The fuel cell according to claim 20, wherein the fuel cell ranges from W / mK to 10 W / mK. 22. The fuel cell according to claim 20, wherein the porosity of the heat insulating material is in a range of 10% to 95%.