JPH05326037A - Battery - Google Patents

Abstract

PURPOSE:To prevent moisture of an electrolyte solution in a battery from evaporating and to suitably maintain internal resistance inside the battery and a discharge characteristic by arranging a polyelectrolyte thin film. CONSTITUTION:In a battery 1 wherein an air pole 5 the active material of which is oxygen is arranged inside a positive electrode vessel 2 provided with air holes 21, a polyelectrolyte thin film 7 containing a functional group to be dissociated from a principal chain or a side chain in an aqueous solution is interposed in a clearance between the air pole 5 and the positive electrode vessel 2. A composite film S may be formed by supporting a fine porous film 10 with the polyelectrolyte thin film 7. An air diffusion porous body may be interposed in a clearance between the composite film S and the air pole 5 side and/or the positive electrode vessel 2 inside. A polytetrafluoroethylene porous film may also be arranged adjacent to the air pole 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery, and its object is to reduce the influence of the environmental change even if the environmental conditions of the outside air such as humidity are changed, and the change of the weight inside the battery and the operating voltage of the battery are small. It is to provide a battery having both a heavy load discharge characteristic that is difficult to receive and a long-term discharge characteristic in an atmosphere of high and low humidity.

[0002]

BACKGROUND OF THE INVENTION At present, the use of "alkaline batteries" is becoming the mainstream as a powerful type battery replacing manganese dry batteries. This "alkaline battery" has an electrolyte of 30-40
% Of potassium hydroxide, it is a high-performance battery that can be continuously used as a power source for motors and lamps and is suitable for continuous discharge of large current. Batteries "," alkaline manganese batteries ", or" mercury batteries "are classified.

However, these alkaline batteries also have various problems. In other words, the "silver oxide battery" has a problem that the price of "silver", which is a raw material, fluctuates so much that a stable supply cannot be provided over a long period of time. However, there was a problem that the voltage gradually decreased. On the other hand, the "mercury battery" has a larger capacity than the "silver oxide battery" and "alkaline manganese battery", and moreover, when discharged, mercury in the positive electrode is reduced and the internal resistance decreases, so the voltage is more constant than the "silver oxide battery". It has excellent performance that it is easy to keep,
Due to the problem of environmental pollution, it is the current situation that the production of such batteries has been refrained from due to the environmental pollution problem. Therefore, in recent years, attention has been paid to "fuel cells" and "air cells" as batteries that hardly use heavy metals such as mercury and have no problem of environmental pollution.

[0004]

2. Description of the Related Art This "fuel cell" has a mechanism in which hydrogen sent to the negative electrode is used as a fuel and oxygen sent to the positive electrode is reacted in an electrolytic solution as an oxidant, and is used in applications such as space development and undersea work. It is a next-generation battery that has received a great deal of attention. Further, the "air cell" is a semi-fuel type button cell in which hydrogen of the negative electrode of the "fuel cell" is zinc, and as shown in FIG. 15, a diffusion paper (k) for diffusing air inside, A positive electrode container (p) with a water-repellent film (c) that controls entry and exit to prevent liquid leakage, an air electrode (b), and a cellophane separator (s), and a mixture of electrolyte and zinc powder. And a negative electrode container (m) provided with a negative electrode zinc (z) composed of (1) and (2) are respectively sealed via a gasket (g). In this air battery (E), an air hole (a) is provided at the bottom of the positive electrode container (p), and the air hole (a) is sealed.
The (t) was peeled off, air was taken in naturally, and the oxygen was used as an active substance.

In the air battery (E) having such a structure, it is easily affected by the external environment, and in particular, water vapor enters and leaves the air electrode (b) due to a change in humidity.
As a result, the performance of the battery is affected. In other words, when the relative humidity of the outside is higher than the relative humidity of the electrolyte, the humidity of the outside air is taken into the battery, so the concentration of the electrolyte decreases, the discharge performance decreases, and the electrolyte leaks. If the external relative humidity is less than or equal to the relative humidity of the electrolytic solution, the electrolytic solution will evaporate, increasing the internal resistance of the battery and increasing the battery life (battery characteristics after being left for a long time). There were problems such as inferiority. Therefore, in order to reduce the influence of such relative humidity, research is underway on a film provided between the air electrode (b) and the air hole (a), and a silicon-based uniform thin film or porous film is used. The development of a film in which a film and an organic compound are combined is being developed.

[0006]

However, in general, a polymer film or membrane has a property of allowing water vapor to permeate better than oxygen, so that not only hydrophilic materials but also hydrophobic materials such as fluororesins can be used. It tends to selectively pass water vapor. Therefore, even if the film is thinned to improve the oxygen permeability or a film having a high oxygen permeability such as a silicone resin is used, the result is that more water vapor is permeated than oxygen. Therefore, when such a membrane is used in a battery, as described above, permeation of water vapor inside and outside the battery is unavoidable, so even if a large amount of oxygen, which is an active substance, is taken in to obtain a high current value,
There has been a problem that properties such as long-term storability, life and discharge characteristics are deteriorated. Therefore, in the industry, it is desired to create a battery that can suppress the permeation of water vapor, selectively permeate only oxygen, and exhibit excellent characteristics even when the environmental conditions of the outside air such as humidity change. Was there.

[0007]

According to the present invention, there is provided a battery in which an air electrode having oxygen as an active substance is provided inside a positive electrode container having an air hole, the air electrode and the positive electrode container. By providing a battery in which a polymer electrolyte thin film containing a functional group that dissociates in an aqueous solution in its main chain or side chain is interposed in the gap, the above-mentioned conventional problems are alleviated.

[0008]

[Function] A battery is formed by interposing a polymer electrolyte thin film having a dissociative group that forms a strong hydration structure with water in a gap between the inside of the positive electrode container and the air electrode. Prevents evaporation of water from the internal electrolyte,
It is possible to suitably maintain the internal resistance and discharge performance in the battery. In particular, when a polymer electrolyte thin film containing at least one or more of a carboxyl group, a sulfone group or a metal salt thereof, a primary to tertiary amino group, a metal salt thereof or an ammonium salt in a main chain or a side chain is used. The prevention of water evaporation is more effectively exhibited. In addition, by supporting a microporous membrane on the polymer electrolyte thin film to form a composite membrane, it is possible to prevent evaporation of water and maintain good oxygen permeability. In addition, when the microporous membrane is arranged inside the positive electrode container, the effect is more remarkably exhibited. When the air diffusion porous body is provided in the gap between the polymer electrolyte thin film and the inside of the positive electrode container and / or the gap between the polymer electrolyte thin film and the air electrode, oxygen can be more effectively sent to the air electrode. it can. Furthermore, when the structure is such that a polytetrafluoroethylene (PTFE) porous film is provided adjacent to the air electrode, high water repellency can be exhibited.

[0009]

DETAILED DESCRIPTION OF THE INVENTION A battery according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional explanatory view showing an embodiment of the battery according to the present invention.
A positive electrode container (2) provided with (1) and a negative electrode container (3) filled with negative electrode zinc (31) are sealed via a gasket (4). Inside the positive electrode container (2), the air electrode (5) and separator
(6) is provided, and oxygen in the air taken in through the air holes (21) is used as the active substance. (7) is a polymer electrolyte thin film having a main chain or a side chain containing a functional group that dissociates in an aqueous solution.

The polymer electrolyte thin film (7) is not particularly limited as long as it is a hydrophilic material having a high ability to retain water vapor and has a dissociative group that forms a strong hydration structure with water. It can be used suitably without As a functional group that dissociates in an aqueous solution, a carboxyl group (-COO
H), sulfone group (--SO3 H) or a metal salt thereof, primary to tertiary amino group _{(-NH 2, -NH -, -} N-)
Alternatively, these metal salts or ammonium salts are exemplified, and a polymer thin film containing at least one or more of these in the main chain or side chain traps the water vaporized from the electrolytic solution in the battery and evaporates the water. It is preferably used because it has the ability to effectively prevent In the present invention, the content of such a functional group is not particularly limited,
When at least 50 mol% is not present during random copolymerization, the effect of trapping water is not exhibited, which is not preferable.

The polymer electrolyte thin film (7) containing the above-mentioned functional group in the main chain or side chain is easily polymerized alone or copolymerized with other monomers from a monomer state such as acrylic acid and methacrylic acid. Obtained. Alternatively, those obtained by copolymerization with other monomers, those obtained by chemically introducing a sulfone group or the like into a general polymer later, and the polymers obtained by radiation such as electron beam or gamma ray or ultraviolet rays. Those obtained by graft- or block-copolymerizing the above-mentioned monomer containing a functional group, which generates a reactive site, are preferably used without limitation.

Such a polymer is dissolved in a suitable solvent, or in the case of a water-soluble polymer or copolymer such as acrylic acid, in order to prevent swelling by water, it is appropriately crosslinked with a crosslinking agent or the like to form a thin film. The polymer electrolyte thin film (7) used in the present invention. Alternatively, in the case of the above-mentioned graft copolymerization, a thin film of a polymer soluble in a solvent or an extrudable polymer is first introduced, and then a functional group is introduced only in the surface layer to form a polymer electrolyte thin film.
(7) may be used. Obtained polymer electrolyte thin film (7)
Is preferably 10 μm or less, more preferably 5 μm or less. The reason is that if the thickness exceeds 10 μm, the polymer electrolyte thin film (7) hinders the supply of oxygen to the air electrode (5), which is not preferable. The polymer electrolyte thin film (7) may have a structure that swells in the presence of water and has microscopic voids, and is not particularly limited.

Such a polymer electrolyte thin film (7) may be disposed in the battery (1) by itself, or if it is weak in strength, as shown in FIG. It may be arranged as a composite membrane (S) by supporting
It may be appropriately determined depending on the strength of the polymer electrolyte thin film (7) used. FIG. 3 is a cross-sectional view showing another embodiment of the battery according to the present invention. In the present invention, as shown in the figure, a composite membrane (composite membrane comprising a polymer electrolyte thin film (7) and a microporous membrane (10) ( Oxygen permeability may be further improved by interposing an air diffusion porous body (8) for diffusing air inside the battery in the gap between S) and the inside of the positive electrode container (2). This air diffusion porous body (8)
As the non-woven fabric, a non-woven fabric made of nylon, polypropylene or the like and having a coarse mesh having a thickness of about 100 to 200 μm is exemplified as a preferred example, but is not particularly limited. Further, as shown in FIG. 4, it may be interposed in the gap between the composite electrode (S) formed by the polymer electrolyte thin film (7) and the microporous membrane (10) and the air electrode (5), or in FIG. As shown in Fig. 7, a multi-layer structure may be provided by interposing them in the gap between the composite membrane (S) and the inside of the positive electrode container (2) and in the gap between the composite membrane (S) and the air electrode (5), respectively, or As shown in FIGS. 6 to 7, an air diffusion porous body (8) may be provided inside the air electrode (5) side of the polymer electrolyte thin film (7) alone or inside the positive electrode container (2). It may be appropriately set according to the performance and the like.

Further, as shown in FIGS. 8 to 14, the polymer electrolyte thin film (7) is used alone, as a composite film (S), or on the air electrode (5) side and / or inside the positive electrode container (2). In the state where the air diffusion porous body (8) is interposed, the polytetrafluoroethylene porous membrane (9) with high water repellency is placed next to the air electrode (5) to further improve the effect of preventing leakage of electrolyte solution. It may be a structure.

[0014]

EXAMPLES The effects of the battery according to the present invention will be described more clearly below with reference to examples. (Example 1) A 5% polyethyleneimine aqueous solution was applied onto a porous polysulfone (PS) microporous membrane (manufactured by Nitto Denko Corporation, thickness: 50 μm) and then crosslinked with tolylene diisocyanate to have a cationic charge. A polymer electrolyte thin film was prepared. A composite membrane of the obtained polymer electrolyte thin film and microporous membrane was designed in the same manner as the battery shown in FIG. 14 (diameter 35
mm, height 13 mm) to obtain the battery of Example 1.
In this battery, a polypropylene non-woven fabric having a thickness of 150 μm was used as an air diffusion porous body in the gap between the composite membrane and the inside of the positive electrode container and in the gap between the composite membrane and the air electrode. Further, a polytetrafluoroethylene porous film was provided adjacent to the air electrode.

(Example 2) A 4% 2-methoxyethanol solution of sulfonated polyether sulfone (S-PES) was added to a polytetrafluoroethylene microporous membrane (pore size: 0.05 μm).
m), and an anionic polyelectrolyte thin film was formed on the microporous membrane to form a composite membrane. The obtained composite film was arranged in the same battery as in Example 1 in the same manner as in Example 1 to obtain a battery of Example 2.

(Example 3) Polyethylene microporous membrane (pore size
(0.1 μm) to generate a radical by irradiating with an electron beam,
Grafting rate by graft polymerization of acrylic acid monomer
A polyelectrolyte thin film having a charge of 60% was formed on the microporous film to form a composite film. The obtained composite membrane was used in Example 1.
A battery similar to that of Example 1 was arranged in the same battery as in Example 3 to obtain a battery of Example 3.

(Embodiment 4) A composite membrane similar to that of Embodiment 1 is illustrated.
The battery of Example 4 was arranged in a battery (diameter 35 mm, height 13 mm) designed similarly to the battery shown in FIG. In this battery, a nonwoven fabric made of polypropylene having a thickness of 150 μm was used as an air diffusion porous body and was interposed only in the gap between the composite membrane and the air electrode. Further, a polytetrafluoroethylene porous film was provided adjacent to the air electrode.

(Example 5) A composite membrane similar to that of Example 1 is illustrated.
The battery of Example 5 was arranged in a battery (diameter 35 mm, height 13 mm) designed similarly to the battery shown in 10. In this battery, a polypropylene non-woven fabric having a thickness of 150 μm was used as an air diffusion porous body and was interposed only in the gap between the composite membrane and the inside of the positive electrode container. Further, a polytetrafluoroethylene porous film was provided adjacent to the air electrode.

Comparative Example A battery was obtained in the same manner as in Example 1 except that a polytetrafluoroethylene porous film having an opening ratio of 8% was used instead of the composite film.

Test Example 1 Oxygen permeability rate (RO2) and water vapor permeability rate (RH2O) of the composite membranes of the polymer electrolyte thin film and microporous membrane prepared in Examples 1 to 5 and Comparative Example, respectively. Was measured. The gas permeability of the film is measured by ASTM-D-1434-63, JIS-
It was performed based on the method disclosed in Z0208. The results are shown in Table 1.

[Table 1]

Test Example 2 The batteries obtained in Examples 1 to 5 and Comparative Example were tested for the following items. Continuous discharge duration (hr) and average operating voltage (V) under conditions of humidity 60% / 25 ° C and load 130Ω. Long-term under humidity 35% / 25 ℃ and humidity 80% / 25 ℃
(1,500 hours) The change in battery weight (mg) and operating voltage (V) due to moisture in and out of the battery after storage. The results are shown in Table 2.

[Table 2]

[0022]

As described in detail above, the present invention is a battery in which an air electrode having oxygen as an active substance is disposed inside a positive electrode container having air holes, wherein the air electrode and the positive electrode are Since the battery is characterized in that the polymer electrolyte thin film containing a functional group that dissociates in the main chain or side chains in an aqueous solution is interposed in the gap with the container, as is clear from the above examples, Due to the high hydrophilicity of the polymer electrolyte thin film, it is possible to prevent the evaporation of water from the electrolytic solution in the battery, and to appropriately maintain the internal resistance and discharge performance in the battery.
In particular, when a polymer electrolyte thin film containing at least one or more of a carboxyl group, a sulfone group or a metal salt thereof, a primary to tertiary amino group, a metal salt thereof or an ammonium salt in a main chain or a side chain is used. The prevention of water evaporation is more effectively exhibited. In addition, by combining a microporous membrane with the polymer electrolyte thin film, it is possible to prevent evaporation of water and to maintain good oxygen permeability. By arranging the inside of the positive electrode container, the effect is more remarkably exhibited. When the air diffusion porous body is provided in the gap between the polymer electrolyte thin film and the inside of the positive electrode container and / or the gap between the polymer electrolyte thin film and the air electrode, oxygen can be more effectively sent to the air electrode. it can. Furthermore, when the structure is such that a polytetrafluoroethylene (PTFE) porous film is provided adjacent to the air electrode, high water repellency can be exhibited.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional explanatory view showing an embodiment of a battery according to the present invention.

FIG. 2 is a schematic cross-sectional explanatory view showing a first modified example of the battery according to the present invention.

FIG. 3 is a schematic cross-sectional explanatory view showing a second modified example of the battery according to the present invention.

FIG. 4 is a schematic cross-sectional explanatory view showing a third modified example of the battery according to the present invention.

FIG. 5 is a schematic cross-sectional explanatory view showing a fourth modified example of the battery according to the present invention.

FIG. 6 is a schematic cross-sectional explanatory view showing a fifth modified example of the battery according to the present invention.

FIG. 7 is a schematic cross-sectional explanatory view showing a sixth modified example of the battery according to the present invention.

FIG. 8 is a schematic cross-sectional explanatory view showing a seventh modified example of the battery according to the present invention.

FIG. 9 is a schematic cross-sectional explanatory view showing an eighth modified example of the battery according to the present invention.

FIG. 10 is a schematic cross-sectional explanatory view showing a ninth modified example of the battery according to the present invention.

FIG. 11 is a schematic cross-sectional explanatory view showing a tenth modified example of the battery according to the present invention.

FIG. 12 is a schematic cross-sectional explanatory view showing an eleventh modified example of the battery according to the present invention.

FIG. 13 is a schematic cross-sectional explanatory view showing a twelfth modified example of the battery according to the present invention.

FIG. 14 is a schematic cross-sectional explanatory view showing a thirteenth modified example of the battery according to the present invention.

FIG. 15 is a schematic cross-sectional explanatory view showing a conventional battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery 2 Positive electrode container 21 Air hole 5 Air electrode 7 Polymer electrolyte thin film 10 Microporous membrane 8 Air diffusion porous body 9 Polytetrafluoroethylene porous membrane S Composite membrane

Claims (7)

[Claims] 1. A battery in which an air electrode having oxygen as an active substance is disposed inside a positive electrode container having an air hole, and a main chain or a gap is provided between the air electrode and the positive electrode container. A battery comprising a side chain and a polymer electrolyte thin film containing a functional group that dissociates in an aqueous solution. 2. A functional group that dissociates in an aqueous solution of the polymer electrolyte thin film is at least one of a carboxyl group, a sulfone group or a metal salt thereof, a primary to tertiary amino group, or a metal salt or an ammonium salt thereof. The battery according to claim 1, wherein the battery is three. 3. The battery according to claim 1, wherein a microporous membrane is supported on the polymer electrolyte thin film to form a composite membrane. 4. The battery according to claim 3, wherein the polymer electrolyte thin film is disposed on the air electrode side and the microporous membrane is disposed on the air hole side. 5. The battery according to claim 3, wherein an air diffusion porous body is interposed in a gap between the composite membrane and the inside of the positive electrode container. 6. The battery according to claim 3, wherein an air diffusion porous body is interposed in a gap between the composite membrane and the air electrode. 7. The battery according to claim 1, wherein a polytetrafluoroethylene porous membrane is provided adjacent to the air electrode.