JP4007883B2 - Liquid fuel cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid fuel cell using a liquid as a fuel.
[0002]
[Prior art]
In recent years, with the widespread use of cordless devices such as personal computers and mobile phones, secondary batteries as power sources are increasingly required to be smaller and have higher capacities. Currently, lithium ion secondary batteries have been put into practical use as secondary batteries that have high energy density and can be reduced in size and weight, and demand for portable power sources is increasing. However, depending on the type of cordless device used, this lithium secondary battery has not yet reached a level that guarantees sufficient continuous use time.
[0003]
In such a situation, an air battery, a fuel cell, etc. can be considered as an example of a battery that can meet the above-mentioned demand (for example, see Patent Document 1 and Patent Document 2).
[0004]
[Patent Document 1]
US Pat. No. 3,419,900 [Patent Document 2]
Japanese Examined Patent Publication No. 37-1054 [0005]
The air battery is a battery that uses oxygen in the air as an active material for the positive electrode, and can be used for filling the negative electrode with most of the battery internal volume. Therefore, the air battery is suitable for increasing the energy density. It is thought that. However, this air battery has a problem that self-discharge is large because an alkaline solution used as an electrolytic solution reacts with carbon dioxide in the air and deteriorates.
[0006]
On the other hand, the conventional fuel cell is configured by stacking unit cells, so that it is bulky, and oxygen and fuel must be circulated and supplied to the respective positive and negative electrodes. Requires auxiliary equipment. As a result, it is much larger than a small secondary battery such as a lithium ion battery, and there is a problem in using it as a small portable power source.
[0007]
[Problems to be solved by the invention]
Here, although the output is reduced by removing the auxiliary device for forcibly circulating oxygen and fuel, the fuel cell can be reduced in size. However, there is a limit to miniaturization in a fuel cell having a laminated structure in which each electrode / electrolyte integrated body is stacked.
[0008]
On the other hand, when a plurality of electrode / electrolyte integrated products are arranged so that the positive electrode (air electrode) and the negative electrode (fuel electrode) are in a flat shape, the fuel tank can be shared, the contact with air is improved, and the laminate The battery can be downsized compared to the structure. However, in that case, when each electrode / electrolyte integrated product is electrically connected in series, there is a problem that liquid fuel leaks from between each electrode / electrolyte integrated product.
[0009]
The present invention provides a liquid fuel cell in which liquid fuel does not leak even if it is reduced in size and can generate power stably.
[0010]
[Means for Solving the Problems]
A liquid fuel cell according to the present invention includes an electrode / electrolyte integrated body composed of a positive electrode that reduces oxygen, a negative electrode that oxidizes fuel, and an electrolyte layer provided between the positive electrode and the negative electrode. A liquid fuel cell comprising a liquid fuel storage unit and a lid for storing
The liquid fuel storage part and the lid part are formed of an electrical insulator;
A plurality of the electrode / electrolyte integrated products are arranged in a plane between the liquid fuel storage unit and the lid,
Current collectors are arranged in thin films on the inner surfaces of the liquid fuel storage part and the lid part,
The electrode / electrolyte integrated products are electrically connected in series by the current collector.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0012]
A liquid fuel cell according to the present invention includes an electrode / electrolyte integrated body composed of a positive electrode that reduces oxygen, a negative electrode that oxidizes fuel, and an electrolyte layer provided between the positive electrode and the negative electrode. A liquid fuel storage part for storing the fuel and a lid part. The liquid fuel storage part and the lid part are formed of an electrical insulator, and a plurality of the electrode / electrolyte integrated bodies are arranged in a plane between the liquid fuel storage part and the lid part. In addition, current collectors are arranged in a thin film on the inner surfaces of the liquid fuel storage unit and the lid unit, and the electrode / electrolyte integrated products are electrically connected in series by the current collectors.
[0013]
By disposing the current collectors on the inner surfaces of the liquid fuel storage part and the lid part in the form of a thin film, there is no gap between the liquid fuel storage part and the lid part and the current collector, and leakage of the liquid fuel can be prevented. In addition, by integrating the liquid fuel storage unit and the lid, and the current collector, there is no problem of the current collector shifting when assembling the battery, and the number of parts can be reduced. It becomes easy. Further, by arranging a plurality of electrode / electrolyte integrated products in a plane between the liquid fuel storage part and the lid part, the liquid fuel storage part can be shared and the battery can be reduced in size as compared with the stacked battery. Furthermore, by forming the liquid fuel storage part and the cover part from an electrical insulator, it is possible to prevent a short circuit between the electrode and electrolyte integrated product.
[0014]
In the liquid fuel cell of the present invention, the current collector preferably has a thickness of 0.5 to 50 μm, more preferably 5 to 30 μm. Thereby, while being able to provide the outstanding liquid-tightness between a liquid fuel storage part and a cover part, the electrical resistance of a collector can be reduced.
[0015]
In the liquid fuel cell of the present invention, it is preferable that the liquid fuel storage part and the lid part are made of at least one kind selected from a resin and an integrated material obtained by coating a metal with an electrically insulating material. Furthermore, the Young's modulus of the metal is preferably 100,000 MPa or more. Thereby, since the strength of the liquid fuel storage portion and the lid portion is increased, the liquid fuel storage portion and the lid portion can be joined with a larger pressure, and leakage of the liquid fuel can be more reliably prevented.
[0016]
In the liquid fuel cell of the present invention, the metal is preferably at least one selected from the group consisting of carbon steel, alloy steel, cemented carbide, aluminum alloy, magnesium alloy, titanium alloy and nickel alloy. This is because these are excellent in durability and strength.
[0017]
In the liquid fuel cell of the present invention, the electrically insulating substance is at least selected from the group consisting of a polymer polyester resin, a phenol resin, an alkyd resin, a vinyl resin, a urethane resin, an epoxy resin, an acrylic resin, and a chlorinated rubber. One type is preferable. This is because these are excellent in strength and electrical insulation. The thickness (layer thickness) of the electrically insulating substance is preferably in the range of 0.1 to 500 μm.
[0018]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
(Embodiment 1)
FIG. 1 is an exploded configuration diagram of a liquid fuel cell according to Embodiment 1 of the present invention.
[0020]
The electrode / electrolyte integrated body 4 includes a positive electrode 4a, a negative electrode (not shown), and an electrolyte layer 4b provided between the positive electrode 4a and the negative electrode. The positive electrode 4a is configured, for example, by laminating a diffusion layer made of a porous carbon material and a catalyst layer made of carbon powder carrying a catalyst. The positive electrode has a function of reducing oxygen, and for example, platinum fine particles, alloy fine particles of iron, nickel, cobalt, tin, ruthenium, gold or the like and platinum are used as the catalyst. The catalyst layer may contain polytetrafluoroethylene (PTFE) resin particles and proton exchange resin particles. As the proton exchange resin particles, for example, polyperfluorosulfonic acid resin, sulfonated polyether sulfonic acid resin, sulfonated polyimide resin or the like can be used. A carbon powder paste containing PTFE resin particles may be applied to the catalyst layer side of the diffusion layer in order to improve water repellency.
[0021]
The electrolyte layer 4b is made of a material that does not have electronic conductivity and can transport protons. For example, polyperfluorosulfonic acid resin membranes, specifically “Nafion” (trade name) manufactured by DuPont, “Flemion” (trade name) manufactured by Asahi Glass Co., “Aciplex” manufactured by Asahi Kasei Kogyo Co., Ltd. (product) The electrolyte layer 4b can be constituted by the name). In addition, it can also comprise a sulfonated polyether sulfonic acid resin film, a sulfonated polyimide resin film, a sulfuric acid-doped polybenzimidazole film, or the like.
[0022]
The negative electrode includes a diffusion layer and a catalyst layer, and has a function of generating protons from the fuel, that is, a function of oxidizing the fuel. For example, the negative electrode can be configured similarly to the positive electrode.
[0023]
The positive electrode 4a, the electrolyte layer 4b, and the negative electrode are joined by hot pressing or the like to form the electrode / electrolyte integrated product 4.
[0024]
A cover plate 1 serving as a lid is disposed on the side of the positive electrode 4a opposite to the electrolyte layer 4b. The cover plate 1 is made of, for example, PTFE, hard polyvinyl chloride, polypropylene, polyethylene, polyallylamide, polyallyl ether ketone, polyether ether ketone, polyether ketone ether ketone ketone, polyether ketone ketone, polyether imide, polyphthal It can be formed of synthetic resin such as amide or glass epoxy resin.
[0025]
Furthermore, when it is desired to further improve the strength of the cover plate 1, the cover plate 1 can be formed from a metal coated with an electrically insulating material. As the metal, for example, carbon steel having a Young's modulus of 100000 MPa or more, alloy steel, cemented carbide, aluminum alloy, magnesium alloy, titanium alloy, nickel alloy and the like are used.
[0026]
As said alloy steel, nickel steel, manganese steel, chromium molybdenum steel, stainless steel, etc. can be used. The cemented carbide is a sintered metal obtained by sintering a metal element carbide powder and a metal powder, and a sintered body of a group 4-6 metal carbide and a metal such as Fe, Ni, and Co in the periodic table. Can be used. As the aluminum alloy, duralumin, super duralumin, super duralumin and the like can be used. As the magnesium alloy, an Mg—Al alloy, an Mg—Zn alloy, an Mg—rare earth element alloy, or the like can be used. As the titanium alloy, any of α type, α + β type, and β type can be used.
[0027]
Examples of the electrically insulating substance include high molecular polyethylene, phenol resin, alkyd resin, vinyl resin, urethane resin, epoxy resin, acrylic resin, and chlorinated rubber.
[0028]
Air holes 2 are provided in portions of the cover plate 1 that are in contact with the positive electrode 4a. Thereby, the positive electrode can come into contact with air, and oxygen is reduced at the positive electrode. A positive electrode current collector 3 is disposed around the portion of the air hole 2 that is in contact with the positive electrode 4a. The positive electrode current collector 3 is, for example, platinum, gold, stainless steel, nickel fine particles, or gold and platinum alloy fine particles adhered to the inner surface of the cover plate 1 using an epoxy resin or silicone in a thin film shape. Or a mixture of these metal fine particles and epoxy resin, silicone, etc. applied to the inner surface of the cover plate 1 as a thin film, or these metal fine particles by sputtering, vacuum deposition, chemical plating, etc. For example, a thin film attached to the inner surface of the cover plate 1 is used. The positive electrode current collector 3 includes a rectangular portion 10.
[0029]
A fuel tank 5 for storing liquid fuel is disposed on the side of the negative electrode opposite to the electrolyte layer 4b. The fuel tank 5 can be formed of the same material as the cover plate 1. As the liquid fuel, for example, methanol aqueous solution, ethanol aqueous solution, dimethyl ether, sodium borohydride aqueous solution, potassium borohydride aqueous solution, lithium borohydride aqueous solution and the like are used.
[0030]
In addition, fuel supply holes 7 are provided in portions of the fuel tank 5 that are in contact with the negative electrode. Thereby, the liquid fuel can come into contact with the negative electrode, and the liquid fuel is oxidized at the negative electrode. A negative electrode current collector 6 is disposed around the portion of the fuel supply hole 7 in contact with the negative electrode. The negative electrode current collector 6 can be formed in the same manner as the positive electrode current collector 3. The negative electrode current collector 6 has a rectangular portion 11.
[0031]
Further, a rectangular annular packing 8 is provided around the fuel supply hole 7. Providing the packing 8 can more reliably prevent liquid fuel from leaking from the gap between the fuel tank 5 and the electrode / electrolyte integrated body 4. As the material of the packing 8, for example, natural rubber, butadiene rubber, styrene rubber, butyl rubber, ethylene / propylene rubber, nitrile rubber, acrylic rubber, urethane rubber, silicone rubber, fluorine rubber, or PTFE resin is used. Can do.
[0032]
A gas-liquid separation hole 9 is disposed in the periphery of the fuel tank 5 and the cover plate 1. Each gas-liquid separation hole 9 of the fuel tank 5 is provided with a gas-liquid separation film 9a. The gas-liquid separation membrane 9a is made of a PTFE thin film having pores, and can discharge carbon dioxide and the like generated by the discharge reaction to the outside without causing liquid fuel to leak.
[0033]
By laminating the cover plate 1, the electrode / electrolyte integrated body 4 and the fuel tank 5, the electrode / electrolyte integrated body 4 and the rectangular portion 10 of the positive electrode current collector 3 are disposed on the negative electrode current collector 6. The adjacent electrode / electrolyte integrated body 4 is disposed under the positive electrode current collector 3. That is, the positive electrode current collector 3 and the negative electrode current collector 6 are in contact with each other through the rectangular portions 10 and 11, and the adjacent electrode / electrolyte integrated products 4 are electrically connected in series. Note that the cover plate 1 and the fuel tank 5 can be joined to each other at an arbitrary pressure using bolts, nuts or the like, although not shown. The liquid fuel cell according to Embodiment 1 of the present invention is configured as described above.
[0034]
(Embodiment 2)
FIG. 2 shows an exploded configuration diagram of the liquid fuel cell according to the second embodiment of the present invention. The present embodiment is configured in the same manner as in the first embodiment except that the positive electrode current collector 3 and the negative electrode current collector 6 are in contact with each other via the narrow strips 12 and 13.
[0035]
【Example】
Next, the present invention will be described more specifically with reference to examples.
[0036]
Example 1
A liquid fuel cell having the same configuration as that of Embodiment 1 was produced as follows.
[0037]
The cover plate 1 was formed from plate-like PTEF having a length of 70 mm, a width of 100 mm, and a thickness of 1 mm. The fuel tank 5 was formed from box-like PTFE (thickness 2 mm) having a length of 70 mm, a width of 100 mm, and a depth of 7 mm. The cover plate 1 and the fuel tank 5 were joined at a pressure of 1 MPa. The positive electrode current collector 3 was made of stainless steel having a thickness of 30 μm. The negative electrode current collector 6 was made of stainless steel having a thickness of 30 μm. The rectangular portions 10 and 11 of the positive electrode current collector and the negative electrode current collector were 40 mm long and 10 mm wide.
[0038]
The positive electrode was formed from a diffusion layer made of carbon paper having a porosity of 78% and a thickness of 280 μm, and a catalyst layer having a thickness of 50 μm formed by supporting platinum particles having a particle diameter of 3 nm on carbon particles having a particle diameter of 30 nm. The negative electrode is composed of a diffusion layer made of carbon paper having a porosity of 78% and a thickness of 280 μm, and a catalyst layer having a thickness of 50 μm formed by supporting platinum-ruthenium alloy particles having a particle diameter of 5 nm on carbon particles having a particle diameter of 30 nm. Formed. As the electrolyte layer, “Nafion” (trade name) manufactured by DuPont was used.
[0039]
A 3% by mass aqueous methanol solution was used as the liquid fuel, and a rectangular annular butadiene rubber packing having a diameter of 2 mm was used as the packing 8.
[0040]
(Example 2)
In the same manner as in Example 1, a liquid fuel cell having the same configuration as that of Embodiment 2 was produced. The lengths 12 and 13 of the positive electrode current collector 3 and the negative electrode current collector 6 were 20 mm and the width was 5 mm.
[0041]
(Example 3)
A liquid fuel cell was produced in the same manner as in Example 1 except that the cover plate 1 and the fuel tank 5 were both made of hard polyvinyl chloride.
[0042]
(Example 4)
A liquid fuel cell was produced in the same manner as in Example 2 except that both the cover plate 1 and the fuel tank 5 were made of hard polyvinyl chloride.
[0043]
(Example 5)
A liquid fuel cell was produced in the same manner as in Example 1 except that both the cover plate 1 and the fuel tank 5 were made of polypropylene.
[0044]
(Example 6)
A liquid fuel cell was produced in the same manner as in Example 2 except that both the cover plate 1 and the fuel tank 5 were made of polypropylene.
[0045]
(Example 7)
A liquid fuel cell was produced in the same manner as in Example 1 except that the cover plate 1 and the fuel tank 5 were both formed of polyethylene.
[0046]
(Example 8)
A liquid fuel cell was produced in the same manner as in Example 2 except that both the cover plate 1 and the fuel tank 5 were made of polyethylene.
[0047]
Example 9
A liquid fuel cell was produced in the same manner as in Example 1 except that the cover plate 1 and the fuel tank 5 were both formed of glass epoxy resin.
[0048]
(Example 10)
A liquid fuel cell was produced in the same manner as in Example 2 except that the cover plate 1 and the fuel tank 5 were both formed of glass epoxy resin.
[0049]
(Example 11)
The cover plate 1 and the fuel tank 5 are both formed by applying phenol resin paint to stainless steel to a thickness of 100 μm, and the cover plate 1 and the fuel tank 5 are joined at a pressure of 10 MPa. Similarly, a liquid fuel cell was produced.
[0050]
(Example 12)
The cover plate 1 and the fuel tank 5 are both formed of stainless steel by applying an epoxy resin paint to a thickness of 100 μm, and the cover plate 1 and the fuel tank 5 are joined at a pressure of 10 MPa, as in Example 2. Similarly, a liquid fuel cell was produced.
[0051]
When the batteries of Examples 1 to 12 manufactured as described above were installed so that the air holes 2 faced down, no leakage of liquid fuel was observed in all the batteries.
[0052]
Next, when the battery in the above installed state was vibrated with a sine wave of 100 Hz for 10 minutes, in the batteries of Examples 1 to 10, some liquid fuel leakage was observed, but in the batteries of Examples 11 and 12, No liquid fuel leakage was observed.
[0053]
【The invention's effect】
As described above, the present invention can provide a liquid fuel cell that does not leak liquid fuel and can stably generate power even if the battery is downsized.
[Brief description of the drawings]
FIG. 1 is an exploded configuration diagram of a liquid fuel cell according to Embodiment 1 of the present invention.
FIG. 2 is an exploded configuration diagram of a liquid fuel cell according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cover plate 2 Air hole 3 Positive electrode collector 4 Electrode / electrolyte integrated body 4a Positive electrode 4b Electrolyte layer 5 Fuel tank 6 Negative electrode collector 7 Fuel supply hole 8 Packing 9 Gas-liquid separation hole 9a Gas-liquid separation membrane 10 Positive electrode current collection Rectangular portion 11 of the body Rectangular portion 12 of the negative electrode current collector Thin band portion 13 of the positive electrode current collector Thin band portion of the negative electrode current collector

Claims (6)

A liquid fuel storage unit that includes a positive electrode that reduces oxygen, a negative electrode that oxidizes fuel, and an electrode / electrolyte integrated body that includes an electrolyte layer provided between the positive electrode and the negative electrode; A liquid fuel cell comprising a lid,
The liquid fuel storage part and the lid part are formed of an electrical insulator;
A plurality of the electrode / electrolyte integrated products are arranged in a plane between the liquid fuel storage unit and the lid,
Current collectors are arranged in thin films on the inner surfaces of the liquid fuel storage part and the lid part,
The liquid fuel cell, wherein the electrode / electrolyte integrated product is electrically connected in series by the current collector. The liquid fuel cell according to claim 1, wherein the current collector has a thickness of 0.5 to 50 μm. 3. The liquid fuel cell according to claim 1, wherein the liquid fuel storage part and the lid part are each made of at least one selected from a resin and a single product obtained by coating a metal with an electrically insulating material. The liquid fuel cell according to claim 3, wherein the metal has a Young's modulus of 100,000 MPa or more. 5. The liquid fuel cell according to claim 3, wherein the metal is at least one selected from the group consisting of carbon steel, alloy steel, cemented carbide, aluminum alloy, magnesium alloy, titanium alloy, and nickel alloy. The electrical insulating material is at least one selected from the group consisting of a high molecular polyester resin, a phenol resin, an alkyd resin, a vinyl resin, a urethane resin, an epoxy resin, an acrylic resin, and a chlorinated rubber. Liquid fuel cell.

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