JP2002015763A - Fuel cell and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small size and thin fuel cell which has a high reliability and is useful as a power source for small apparatuses and can generate a stable output for a long time. SOLUTION: This is a fuel cell which comprises plural unit cells arranged adjoined along a first direction with a prescribed interval. The unit cell comprises a fuel electrode, a oxidizer electrode arranged opposed to the fuel electrode, an electrolyte layer held by the fuel electrode and the oxidizer electrode in between, and a fuel vaporizer which adjoins the fuel electrode and vaporizes the supplied liquid fuel. The fuel electrode, the oxidizer electrode, the electrolyte layer, the fuel infiltrating layer and the fuel vaporizer are arranged in the second direction that crosses at right angles the first direction. The plural unit cells are joined by using the thin film of the outer packing material and sealed by gas and liquid in one lot, and the joining portion of the unit cells that are arranged adjoined functions as a generated water absorbing and releasing portion for releasing the water that is generated by reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art At present, there is known a fuel cell having an electromotive section having a fuel electrode and an oxidant electrode and an electrolyte plate sandwiched between both electrodes, and using a liquid fuel as a fuel. This type of fuel cell has a fuel permeable layer for introducing liquid fuel into the cell by capillary force, and is disposed between the fuel permeable layer and the fuel electrode to vaporize the liquid fuel introduced into the cell. And a fuel vaporization layer for supplying the fuel electrode in the form of a gaseous fuel to enable the liquid fuel to be vaporized inside.

[0003] Such a fuel cell can use a high-concentration liquid fuel and can be expected to have a high output despite its small size, but the reaction produces water. Since the generated water remains and hinders the reaction, a stable output cannot be obtained for a long time.

In the case of a fuel cell including a plurality of unit cells, it is necessary to increase the power generation voltage by connecting the unit cells in series, and a method of stacking unit cells has conventionally been used as a connection method. Have been. However, when this method is used, there is a problem in that it is difficult to sufficiently bring out the original battery characteristics due to a failure in assembly due to a displacement of each member at the time of lamination.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional fuel cell and has high reliability.
It is an object of the present invention to provide a small and thin fuel cell which is useful as a power source for a small device and can take out a stable output for a long time.

Further, the present invention produces a small and thin fuel cell which has high reliability, is useful as a power source for small equipment, and can take out a stable output for a long period of time without occurrence of displacement. The aim is to provide a method that can do this.

[0007]

According to the present invention, there is provided a fuel cell having a plurality of unit cells arranged adjacent to each other along a first direction at a predetermined interval. The unit cell includes 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 supplied adjacent to the fuel electrode. A fuel vaporizer for vaporizing fuel, wherein a fuel electrode, an oxidizer electrode, an electrolyte layer, a fuel permeable layer, and a fuel vaporizer in the unit cell are arranged in a second direction orthogonal to the first direction. The plurality of unit cells arranged adjacent to each other are connected by using a thin film as an exterior material, are collectively sealed with gas and liquid, and a connection portion of the unit cells arranged adjacent to each other is To produce the water generated by the reaction It provides a fuel cell, which is a water-absorbing release portion.

The present invention is also a method of manufacturing a fuel cell having a plurality of unit cells arranged adjacent to each other along a first direction at a predetermined interval. An oxidizer electrode, an electrolyte layer sandwiched between the fuel electrode and the oxidizer electrode, a fuel permeable layer that supplies liquid fuel to the fuel electrode by capillary force, and an oxidant electrode that is supplied adjacent to the fuel electrode. Preparing a unit cell including a fuel vaporizer for vaporizing the liquid fuel; and setting the unit cell so that a stacking direction of each member constituting the unit cell is a direction orthogonal to the first direction. Arranging a plurality of adjacent unit batteries along the first direction at intervals of: and connecting the plurality of unit batteries arranged adjacent to each other by using a thin film as an exterior material, and collectively forming gas / gas. It is characterized by having a step of liquid sealing To provide a method of manufacturing a fuel cell.

It is preferable that the end of the unit cell in the fuel cell of the present invention has a generated water absorbing / discharging portion for discharging generated water generated by the reaction.

Further, the fuel cell according to the present invention is bent between the generated water absorbing / discharging portion and the unit cell so that two unit cells adjacent to each other via the generated water absorbing / discharging portion can be arranged to face each other. Preferably it is possible.

When a fuel cell having a folded structure is manufactured by folding between the produced water absorbing / discharging portion and the unit cell, a fuel tank for containing the liquid fuel supplied to the fuel electrode is provided; An oxidizing gas suction layer for supplying an oxidizing gas to the oxidizing electrode may be provided in the folded portion.

Alternatively, when the fuel electrode side surface and the oxidant electrode side surface are alternately folded and folded, the fuel tank and the oxidant gas suction layer are integrally provided in a folded portion. Is also good.

The method of manufacturing a fuel cell according to the present invention further comprises a step of providing a generated water absorbing / discharging section for discharging generated water generated by the reaction at intervals between the plurality of unit cells arranged adjacent to each other. It is preferable that the method further includes a step of bending between the generated water absorption / release unit and the unit battery, and disposing two unit cells adjacent to each other via the generated water absorption / release unit.

In order to connect a plurality of unit batteries arranged in a row adjacent to each other at a predetermined interval with a thin film as an exterior material and to perform gas / liquid sealing at a time, an ultrasonic heating hot roller method is used. Can be used.

Hereinafter, the present invention will be described.

In the fuel cell according to the present invention, a plurality of unit cells are arranged in a line at a predetermined interval on the same plane, and these unit cells are collectively sealed with an exterior material.・ Thinning can be achieved. In particular, when the generated water absorbing / discharging portions are provided at the intervals and ends of adjacent unit cells, the generated water generated by the reaction can be easily removed, and the oxidizing gas flow passage is maintained. . Thereby, the effective area of the electromotive section can be made 100%.

It is preferable that the produced water absorbing / discharging portion is formed of a porous material, whereby the absorbed produced water can be released more easily. Since the generated water absorption / release section is kept at a lower temperature than the unit battery section,
The vaporized product water is condensed and collected in the product water absorption / release section.

Further, when the fuel cell of the present invention can be bent between the produced water absorbing / discharging portion and the unit cell, a fuel tank containing liquid fuel supplied to the fuel electrode, and a fuel tank containing liquid fuel supplied to the oxidant electrode are provided. The oxidant gas suction layer to be formed can be provided in the folded portion. As a result, the size can be further reduced. Alternatively, in the fuel cell of the present invention, the surface on the fuel electrode side and the surface on the oxidant electrode side may be alternately arranged and folded. In this case, the above-described fuel tank and the oxidizing gas suction layer can be integrally provided at the folded portion.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a configuration of an example of the fuel cell of the present invention. FIG. 1A shows a plan view of the fuel cell of the present invention, and FIG. 1B shows a side view thereof.

As shown in FIG. 1A, in a fuel cell 10 according to the present invention, a plurality of unit cells 11 are arranged adjacent to each other at a predetermined interval on the same plane.
The oxidant electrode side lead 12 and the fuel electrode side lead 13 are respectively drawn out. Further, an oxidizing gas inlet 14 and a generated water discharge unit 15 are provided in each unit cell 11, and a generated water absorption / discharge unit 16 is provided between adjacent unit cells 11. The generated water absorbing / discharging section 16 is preferably formed of, for example, a porous body having a porosity of 80% and a pore diameter of 0.5 μm, whereby the absorbed generated water can be released more easily.

The plurality of unit cells 11 and the generated water absorbing / discharging portion 16 therebetween are collectively sealed with an exterior material (thin film) 17.

As shown in FIG. 1 (b), the fuel cell according to the present invention has a side surface in which the generated water absorbing / discharging portion 16 is formed.
Is preferably lower than the unit battery 11. Specifically, a generated water absorption / discharge unit 16 is provided at an interval between a plurality of unit batteries 11 arranged adjacent to each other at a predetermined interval and at an end of the unit battery 11. Thereby, the generated water generated in the unit battery 11 can be efficiently discharged from the generated water absorption / release unit 16.

FIG. 2 schematically shows a part of the fuel cell 10 according to the present invention. 2A is a plan view and a side view of the unit battery 11, and FIG. 2B is a cross-sectional view illustrating an internal configuration of the unit battery 11.

As shown in FIG. 2A, an internal connection lead 18 for connecting adjacent unit cells 11 may be provided.

In the unit cell 11, as shown in FIG. 2 (b), a solid electrolyte membrane 23 is sandwiched between two electrodes of a fuel electrode 21 and an oxidant electrode 22. An electromotive section is constituted by the agent electrode 22 and the solid electrolyte membrane 23. The fuel electrode 21 is generally formed of carbon particles, and a fuel cell catalyst typified by platinum or an alloy thereof is supported on the surface thereof. The oxidant electrode 22 contains a catalyst typified by platinum or the like.

Further, a fuel holding layer 24 for supplying liquid fuel by capillary force is disposed adjacent to the fuel electrode 21, while an oxidizing gas diffusion layer 25 is provided adjacent to the oxidizing electrode 22. Have been. Further, between these layers, a fuel vaporizing section (not shown) for vaporizing the liquid fuel is provided.

In the fuel cell of the present invention, power is generated by the following mechanism. First, liquid fuel is supplied from outside to the fuel holding layer 24 by capillary force.

The fuel holding layer 24 can be made of any material such as a porous organic material such as polyester and polyolefin, a porous inorganic material such as carbon and alumina, and a net-like porous metal material. The fuel supplied to the fuel permeation layer evaporates in the fuel vaporization section and is supplied to the electromotive section in gaseous form.

It should be noted that the vaporizing portion may be a material that is physically present (a porous material similar to the above-described fuel-penetrating material) or may be a space in which the fuel-penetrating material is merely a hole. Is also available.

The vaporized liquid fuel supplied to the fuel electrode 21 is reformed by the above-described fuel cell catalyst therein to extract protons. Electrons are extracted during the fuel reforming. The extracted protons pass through the oxidant electrode 22 through the solid electrolyte membrane 23 provided adjacently.
Transmitted to the side.

On the other hand, on the oxidant electrode 22 side, the protons carried through the solid electrolyte membrane 23 react with the electrons flowing through the external circuit and the oxidant gas (eg, oxygen or air) to form water. Proceeds on the catalyst. The electrons taken out in the course of the reaction as described above flow through an external circuit, thereby generating power and driving an external load.

Here, the packaging material (thin film) 17 used in the fuel cell of the present invention will be described in detail. The exterior material also functions as a fuel leakage prevention film,
For example, the outer shape of the sheet battery is formed in a sheet shape.
Such an exterior material can be formed of a single material or a plurality of materials. Further, the structure may be a single layer structure or a multilayer structure.

Preferred examples of the exterior material include those having a multilayer structure in which a protective layer containing a resin material, a metal layer containing a metal material, and an adhesive layer containing an adhesive are laminated. With such a multilayer structure, resistance to external damage can be increased, and moisture resistance can be further improved. In particular, by including the metal layer, the moisture-proof effect is further enhanced.

Specifically, examples of the material for forming the protective layer include films of polyester, nylon, polycarbonate, polyarylate, liquid crystal polyester, polyphenylene sulfide, polysulfone, and polyetheretherketone.

As a material for forming the metal layer, for example,
Metal foils such as aluminum, copper, and stainless steel are included.

As a material for forming the adhesive layer, for example, ethylene vinyl acetate copolymer (EVA), ethylene acrylic acid copolymer (EAA), ethylene ethyl acrylate copolymer (EEA), and modified polypropylene resin And other olefin-based hot-melt adhesives.

The thickness of the exterior material in the present invention is preferably set to about 60 μm to 300 μm regardless of the structure. When the thickness is less than 60 μm, the strength is not sufficient because the surface is easily broken when the surface is scratched.
If it exceeds μm, the handleability is poor when forming the exterior, and gas and liquid leakage may occur.

The thickness of the exterior material may be different between one and the other. For example, when the exterior material is a laminate including the above-described protective layer, metal layer, and adhesive layer, the protective layer is about 10 μm to 100 μm, the metal layer is about 15 μm to 100 μm, and the adhesive layer is 30 μm.
It is preferably about 100 μm.

In the fuel cell of the present invention, as shown in FIG. 1, it is preferable that a produced water absorbing / discharging section 16 is provided between two adjacent unit cells 11. Further, in this case, as shown in FIG.
It is preferable that it can be bent between 6 and the unit battery 11. As shown in the figure, by bending the both ends of the generated water absorbing / discharging portion 16 so that two adjacent unit cells 11 face each other, it is possible to further reduce the size.

As shown in FIG.
As shown in FIG. 4, in a case where the fuel cell 26 can be bent between the fuel cell 26 and the unit cell 11, a fuel tank 26 containing liquid fuel supplied to the fuel electrode and an oxidant supplied to the oxidant electrode are provided. By providing the gas suction layer 25 in the folded portion, compactness can be achieved. Alternatively, FIG.
As shown in (2), when the fuel electrode side surface and the oxidant electrode side surface are alternately arranged and folded, the fuel tank 26 and the oxidant gas absorbing layer 25 can be integrally provided in the folded portion. .

Next, the fuel cell of the present invention will be described in more detail with reference to examples. The following examples are provided for easy understanding of the contents, and do not limit the present invention.

Example 1 In this example, a small fuel cell having the configuration shown in FIG. 1 was manufactured by 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.

Further, 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 obtain a paste. This was applied to a carbon cloth and dried to form a catalyst layer on the oxidant electrode side.

The fuel electrode and the oxidizer electrode prepared as described above were cut into 20 mm × 75 mm, respectively, and an electrolyte membrane (perfluorosulfonic acid membrane) having a thickness of 200 μm was obtained.
Was pinched. 100 kg of these at 135 ° C for 15 minutes
/ Cm ² to form an electromotive section.

The obtained electromotive section is disposed so as to face the fuel electrode side in common, and a fuel holding layer (polyolefin plate) provided with a large number of holes having a diameter of 8 mm as a fuel vaporizing section in contact with the fuel electrode. , Thickness 2 mm). On the oxidant electrode side, a Teflon (registered trademark) sheet, which is a gas diffusion layer provided with a large number of holes having a diameter of 5 mm, was installed. After arranging five unit batteries obtained in this manner, the whole was thin-filmed. Enclosed with an exterior film.

The thin film packaging film used here was produced as follows. First, a polyester film (outside diameter 100 mm × 800 mm, thickness 16 μm) and an aluminum metal foil (outside diameter 100 mm × 800 mm,
(With a thickness of 20 μm) by a dry lamination method using a urethane-based adhesive. Furthermore, a thin film exterior film is formed by laminating a hot melt adhesive made of ethylene vinyl acetate copolymer (EVA) on a metal foil in advance so as to have a thickness of 0.050 mm by thermal bonding. Produced.

In each unit battery, an aluminum lead terminal having an oval cross section (width 3 mm, thickness 100 μm) and length 100 mm was connected to the positive electrode.
On the other hand, a nickel lead terminal having an oval cross section (width 4 mm, thickness 50 μm) and length 100 mm was connected to the negative electrode.

Next, using the exterior material obtained above, heat-sealing was performed only on two sides of the four peripheral edges, and the laminate was accommodated. Note that the heat sealing is performed at a position within 10 mm inward from the outer periphery of the exterior member. further,
One of the two sides that were not joined was heat-sealed under the same conditions as above. The remaining one side that had not been joined was heat-sealed under the same conditions as above to obtain a sheet battery of the present invention.

A 1: 1 (weight ratio) mixture of methanol and water was supplied from a fuel tank provided outside the small fuel cell 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.

FIG. 6 is a graph showing the relationship between the current density and the output density of the fuel cell of this embodiment. As shown in the graph of FIG. 6, the fuel cell of this embodiment has a current density of about 180 m.
A / cm ² , and the output was about 65 mw / cm ² . Although not shown, the output density was about 55 mw / cm ² at a current density of 150 mA / cm ² , and a stable voltage was maintained even after about 12 hours had passed.

From the above results, the fuel cell of this embodiment is
It was confirmed that the fuel cell was highly reliable as a small fuel cell.

(Example 2) Unit batteries were prepared in the same manner as in Example 1 and arranged on a plane in the same manner as described above.
Between the adjacent unit cells, a generated water discharging section for discharging generated water generated by the reaction was provided. Further, the unit cells were collectively sealed using the same thin film as described above as an exterior material, to obtain a fuel cell of this example.

FIG. 6 is a graph showing the relationship between the current density and the output density of the fuel cell of this embodiment. As shown in FIG. 6, the fuel cell of this embodiment has a current density of about 230 m.
A / cm ² and output were 100 mw / cm ² . Although not shown, the output density was about 90 mw / cm ² at a current density of 200 mA / cm ² , and a stable voltage could be maintained even after about 12 hours had passed.

From the above results, the fuel cell of this embodiment is
It was confirmed that the fuel cell was highly reliable as a small fuel cell.

(Comparative Example 1) First, a unit battery was manufactured in the same manner as in Example 1 described above. Five of the obtained unit cells were stacked, and a fuel cell of Comparative Example 1 was produced without sealing with a thin film as an exterior material.

FIG. 6 is a graph showing the relationship between the current density and the output density of the fuel cell of this comparative example. As shown in FIG. 6, the load could not be reduced as compared with the first embodiment. Although not shown, a drop in voltage was observed after about 1 hour, and the stability was inferior to the fuel cells of the present invention (Examples 1 and 2) using a thin film as an exterior material. It has been found.

[0059]

As described above in detail, according to the present invention, a small and thin fuel cell which has high reliability, is useful as a power source for small equipment, and can take out a stable output for a long time. Is provided. Further, according to the present invention, a small and thin fuel cell which has high reliability, is useful as a power source for small equipment, and can take out a stable output for a long period of time is manufactured without occurrence of displacement. A method of obtaining is provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an electromotive member in an example of a fuel cell of the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of an example of a unit cell in the fuel cell of the present invention.

FIG. 3 is a schematic diagram showing another example of the fuel cell according to the present invention.

FIG. 4 is a schematic diagram showing another example of the fuel cell according to the present invention.

FIG. 5 is a schematic diagram showing another example of the fuel cell according to the present invention.

FIG. 6 is a graph showing a relationship between a current density and an output density.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Fuel cell 11 ... Unit cell 12 ... Oxidant electrode side lead 13 ... Fuel electrode side lead 14 ... Oxidant gas intake 15 ... Generated water discharge part 16 ... Generated water absorption / release part 17 ... Exterior material 18 ... Internal connection lead DESCRIPTION OF SYMBOLS 21 ... Fuel electrode 22 ... Oxidizer electrode 23 ... Solid electrolyte membrane 24 ... Fuel holding layer 25 ... Oxidant gas diffusion layer 26 ... Fuel tank

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01M 8/10 H01M 8/10 (72) Inventor Yoshihiko Nakano 1 No. 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture. 5H026 AA06 AA08 BB01 BB02 BB04 CC01 CV06 CV10 CX01 CX04 CX05 CX07 CX09 EE02 EE05 EE08 EE18 HH03 5H027 AA06 BA13 BC14

Claims (5)

[Claims] 1. A fuel cell having a plurality of unit cells arranged adjacent to each other along a first direction at a predetermined interval, wherein the unit cell has a fuel electrode, and is opposed to the fuel electrode. An oxidizer electrode disposed, an electrolyte layer sandwiched between the fuel electrode and the oxidizer electrode, and a fuel vaporizer that is adjacent to the fuel electrode and vaporizes the supplied liquid fuel. The fuel electrode, the oxidizer electrode, the electrolyte layer, the fuel permeable layer, and the fuel vaporization unit are arranged in a second direction orthogonal to the first direction. Connected using a thin film as a material,
The fuel cell according to claim 1, wherein the connection part of the unit cells, which is liquid-sealed and adjacent to each other, is a generated water absorption / release part for discharging water generated by the reaction. 2. The fuel cell according to claim 1, wherein an end of the unit cell has a generated water absorbing / discharging portion for discharging generated water generated by the reaction. 3. The battery pack according to claim 1, wherein two unit cells adjacent to each other via the generated water absorbing / discharging unit can be disposed so as to face each other. The fuel cell according to claim 1 or 2, wherein 4. A method for manufacturing a fuel cell having a plurality of unit cells arranged adjacent to each other along a first direction at a predetermined interval, comprising: a fuel electrode; The oxidizer electrode, the electrolyte layer sandwiched between the fuel electrode and the oxidizer electrode, a fuel permeable layer that supplies liquid fuel to the fuel electrode by capillary force, and a liquid fuel supplied adjacent to the fuel electrode. Preparing a unit cell including a fuel vaporizing unit to be vaporized, the unit cells are arranged at predetermined intervals so that the stacking direction of each member constituting the unit cell is a direction orthogonal to the first direction. A step of arranging a plurality of adjacent unit cells along the first direction, and connecting the plurality of unit cells arranged adjacent to each other by using a thin film as an exterior material, and performing gas / liquid sealing at a time Fuel cell characterized by comprising a process The method of production. 5. A step of providing a generated water absorbing / discharging section for discharging generated water generated by a reaction at intervals between the plurality of unit cells arranged adjacent to each other; 5. The method for manufacturing a fuel cell according to claim 4, further comprising a step of folding the unit cell and arranging two unit cells adjacent to each other via the generated water absorbing / discharging unit.