JP3260931B2 - Alkaline battery separator using alkali-resistant fiber and alkaline battery using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkaline battery separator using alkali-resistant fibers and an alkaline battery using the same.

[0002]

2. Description of the Related Art Conventionally, a separator has been used so that a positive electrode and a negative electrode of an alkaline battery can be separated to prevent a short circuit, and at the same time, an electrolytic solution can be held and a electromotive reaction can be carried out smoothly.

[0003] Conventional alkaline secondary battery separators are:
Provided in the form of woven or non-woven fabrics, the fibers constituting the woven or non-woven fabric are polyamide fibers, and generally use a potassium hydroxide solution as an electrolyte. Thus, there has been a problem in that the positive electrode and the negative electrode are short-circuited.

For this reason, it has been considered to use a separator using a polyolefin fiber such as a polypropylene fiber. However, since the polyolefin fiber is hydrophobic and has a low affinity for an electrolyte, the retention of the electrolyte is poor. There was a problem of bad.

[0005] Further, in the separator using the above-mentioned polyamide-based fiber or polyolefin-based fiber, during discharge and / or charge, a dendritic metal precipitates on the electrode plate, that is, a short circuit occurs due to so-called dendrite, and the service life is shortened. There was also the problem of being short.

On the other hand, the separator of the conventional alkaline primary battery is provided in the form of non-woven fabric or paper, and the non-woven fabric or paper is made of vinylon fiber or polyvinyl alcohol fiber, and a potassium hydroxide solution is used as an electrolyte. However, there is a problem that the fibers are eroded by the electrolytic solution during use, and the positive electrode and the negative electrode are short-circuited.

Further, pulp such as mercerized pulp and linter pulp is used in order to enhance the retention of the electrolyte in the separator.
Or, in order to suppress the generation of hydrogen in the electrolytic solution, due to the action of aluminum added to the zinc constituting the negative electrode, at the time of discharge, a short circuit occurs due to dendrites that deposit dendritic zinc oxide on the electrode plate, There has also been a problem that the service life is short, such as abnormal voltage drop.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a separator for an alkaline battery which is not affected by an alkali solution such as a potassium hydroxide solution, has an excellent liquid retention property for an alkali solution, and also has an excellent anti-dendritic property. It is to provide a long alkaline battery.

[0009]

According to the present invention, there is provided a battery for an alkaline battery according to the present invention .
Separator (hereinafter sometimes referred to as "separator")
Is the general formula

Embedded image (Wherein, R ₁ is a quaternized aromatic nitrogen-containing heterocyclic residue, R ₂ is a hydrogen atom or an alkoxy group, R ₃ is a hydrogen atom or an acyl group, m is 0 or 1, and n is 1 to 1. Cross-linked polyvinyl alcohol (hereinafter sometimes referred to as “PVA”) having a structural unit represented by the following formula (natural number of 6):
(Hereinafter sometimes referred to as “cross-linked PVA”)
It is made of a fiber sheet containing lukari fibers.

A fiber in which the separator of the present invention contains an adhesive fiber
Made of sheet, excellent dimensional stability of separator
You.

The alkaline battery of the present invention is an alkaline battery using the above separator.

[0012]

The cross-linked PVA contained in the alkali-resistant fiber of the present invention is not easily decomposed by an alkaline electrolyte such as potassium hydroxide, has an affinity for the alkaline electrolyte, and has a liquid retaining property. The separator containing the alkali-resistant fiber is excellent in alkali resistance and liquid retention, and is capable of chelating ions and ions before the dendritic metal is deposited on the electrode plate during discharging and / or charging. Is formed, and ions can be trapped, a dendritic metal is hardly precipitated, and a short circuit due to dendrite is unlikely to occur. Further, since the crosslinked PVA has excellent heat resistance, it is a separator that can withstand use under a high temperature state such as trickle charge. As described above, since the separator of the present invention is excellent in alkali resistance, liquid retention properties and dendrite prevention properties, an alkaline battery using this separator can be used for a long time. Note that formation of a chelate with ions and trapping of ions has been confirmed by experimental examples described later.

The PVA of the present invention has a structural unit represented by the following general formula.

Embedded image In the formula, R ₁ is a quaternized aromatic nitrogen-containing heterocyclic residue, R ₂ is a hydrogen atom or an alkoxy group, R ₃ is a hydrogen atom or an acyl group, m is 0 or 1, and n is 1 And R ₁ is a pyridinium group, a quinolinium group, an isoquinolinium group, a pyrimidinium group, a thiazolium group, a benzothiazolium group, a benzoxazolium group, or the like. May have a substituent such as an alkyl group, an alkoxyl group, an amino group, and a carbamoyl group. R ₂ is, for example, a hydrogen atom or an alkoxy group such as a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group. R ₃ is, for example, a hydrogen atom or an acyl group such as a formyl group, an acetyl group, a propionyl group, a butyryl group, an isobutyryl group.

More specifically, chemical formulas 4 to 7 in which R ₃ is a hydrogen atom and chemical formula 8 in which R ₃ is an acetyl group can be exemplified.

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The hydroxyl group of this PVA is preferably present in an amount of at least 20 mol%, more preferably at least 40 mol%, most preferably at least 80 mol%, based on the monomer unit of the PVA so as to easily form a chelate with ions. % Or more. In addition, the aromatic nitrogen-containing heterocyclic residue is crosslinked with the side chain containing the aromatic nitrogen-containing heterocyclic residue, but the aromatic nitrogen-containing heterocyclic residue is based on the monomer unit of PVA so as not to inhibit the chelate formation between the hydroxyl group and the ion. , 20 mol% or less,
The content is preferably 0.5 mol% or more so as not to impair the electrolytic solution resistance and heat resistance due to the crosslinking. More preferably, it is 1 to 10 mol%.

The degree of polymerization of PVA is 500 or more, and the degree of saponification is 70 to 100%, and is not particularly limited.

If the PVA is partially formed of a hydrophobic portion with an aldehyde compound such as butyl aldehyde, for example, flexibility is generated and handleability can be improved.

The alkali-resistant fiber of the present invention is a fiber containing the above-mentioned crosslinked PVA. For example, a fiber consisting of only the crosslinked PVA obtainable by a wet spinning method may be used, or the crosslinked PVA may be a component of the fiber. As one of them, a spun fiber may be used, or a fiber in which crosslinked PVA is partially or entirely adhered to a fiber surface such as a regenerated fiber, a semi-synthetic fiber, a synthetic fiber, a plant fiber, and an animal fiber may be used.

The alkali-resistant fiber having the crosslinked PVA attached to the fiber surface will be described below.

As a method of attaching the crosslinked PVA to the fiber surface, for example, a method of attaching the crosslinked PVA with an adhesive, or spraying, impregnating, or applying an uncrosslinked PVA solution to the fiber is used. Later, there is a method of crosslinking. In the latter case, no adhesive is used,
This is a preferred method of attachment since it does not reduce the performance of the crosslinked PVA.

There is no particular problem when the cross-linked PVA is completely adhered to the fiber surface. However, when the cross-linked PVA is partially adhered, there is a possibility that the non-adhered portion has poor alkali resistance. Therefore, as the fiber to which the cross-linked PVA is attached, polyethylene fibers having excellent alkali resistance, polyolefin fibers such as polypropylene fibers, core-sheath type,
Side-by-side type, eccentric type, or FIGS. 1 (a) to 1 (d)
1 has a chrysanthemum-shaped fiber cross-section in which one component 1 is disposed between other components 2, or as shown in FIG.
Polyolefin-based fibers such as splittable or non-splittable conjugate fibers having a fiber cross-section in which one component 1 and another component 2 are alternately laminated in a layered manner can be suitably used. In particular, cross-linked PVA
In the case where the fiber to which is attached is a splittable conjugate fiber, a polyolefin splittable conjugate fiber is preferably used because after splitting, it becomes an ultrafine fiber having a portion to which no cross-linked PVA is attached.

The nonwoven fabric obtained by dividing the polyolefin-based splittable conjugate fiber into ultrafine fibers or the nonwoven fabric obtained by a melt-blowing method has a large surface area and therefore has a high affinity for an electrolytic solution, and the distance between the entanglement points of the fibers is small. The separator is short and has minute and dense voids, so that a capillary effect is generated, the liquid retention is more excellent, and furthermore, it is possible to physically prevent a short circuit due to dendrite, so that the separator can be used for a long time. In addition, since the ultrafine fibers obtained by dividing the polyolefin-based splittable conjugate fibers can be obtained by splitting at the same time as entanglement by a water stream, not only is it preferable in production, but the resulting nonwoven fabric is also excellent in strength, It is excellent in workability when assembling batteries and can be used preferably.

In the present invention, an adhesive fiber may be included in addition to the fiber containing the crosslinked PVA to improve the dimensional stability of the separator and further improve the handleability. It is preferable to use all-melt type polyethylene fiber and polypropylene fiber polyolefin-based fiber having excellent alkali resistance and partially melted core-sheath type, side-by-side type and eccentric type polyolefin-based composite fiber also having excellent alkali resistance. In addition, it is also possible to bond with the adhesive resin component generated from the splittable conjugate fiber containing the adhesive resin component.

The separator of the present invention contains a woven fabric such as a plain weave, a twill weave, a satin weave, a wet method, a spun bond method, a melt blow method, a hydroentanglement method, a needle punch method, a partial or full surface containing the above-mentioned fibers. A fiber sheet such as a nonwoven fabric or a knitted fabric obtained by a method such as a thermocompression bonding method.

When the separator of the present invention contains 10% by weight or more of fibers containing cross-linked PVA, the separator is excellent in liquid retention and dendrite prevention.

The separator of the present invention obtained as described above can be used for an alkaline primary battery or an alkaline secondary battery. For example, when used as a cylindrical alkaline manganese primary battery, the negative electrode portion is made of copper. Around the current collector of the negative electrode consisting of a brass rod, a negative electrode mixture layer obtained by adding an alkali solution and a gelling agent such as carboxymethylcellulose to the amalgamated zinc powder and kneading it, and the positive electrode part is made of manganese dioxide. A positive electrode mixture layer composed of a mixture of carbon powder and a nickel-plated steel plate serving as a positive electrode current collector and a terminal formed outside the positive electrode mixture layer; The separator of the present invention is used so as to separate the layer from the positive electrode mixture layer. Even when zinc is used for the negative electrode as in the alkaline manganese primary battery, if the separator of the present invention is used, even if mercury is not used to suppress the elution of zinc, short-circuiting due to dendrite may occur. It does not cause any environmental problems because it can be prevented. Furthermore, since there is no need to use pure zinc, as in the case of using no mercury, there is also a reduction in the energy required to obtain pure zinc, and a cost advantage.

On the other hand, for example, when used in a cylindrical nickel-cadmium sealed secondary battery, a negative electrode made of a porous material mainly composed of metal cadmium particles and a positive electrode filled with nickel hydroxide in the porous material are used. Then, with the separator of the present invention interposed, spirally wound into a cylindrical shape, the cylindrical shape is stored together with the electrolytic solution in a cylindrical nickel-plated steel case, and sealed.

When the separator of the present invention is used in a nickel-hydrogen battery, self-discharge can be suppressed,
A battery with a long service life can be obtained. This is because the separator of the present invention can suppress the movement of the metal eluted from the hydrogen storage electrode to the positive electrode, which is the main cause of the self-discharge in the nickel-hydrogen battery, by the adsorption of the separator of the present invention. Since the separator of the present invention can adsorb the eluted metal, the same effect is obtained in other secondary batteries.

The alkaline primary battery of the present invention may be cylindrical or button-shaped, and the shape is not limited. On the other hand, the alkaline secondary battery may be an open type or a closed type, and the shape may be a cylindrical shape, a flat shape, or a square shape, and this point is not limited. The separator of the present invention is, for example, a primary battery such as an alkaline manganese battery, a mercury battery, a silver oxide battery, an air battery, a nickel-cadmium battery, a silver-zinc battery, a silver-cadmium battery, a nickel-zinc battery, a nickel-hydrogen battery. It can be used for secondary batteries.

Hereinafter, examples of the separator of the present invention will be described, but the present invention is not limited to the following examples.

[0031]

【Example】

(Experiments 1 to 9) As shown in Table 1, 13% by weight of an uncrosslinked state in which PVA containing various styrylpyridinium-based residues and having a chelate-forming hydroxyl group (Experiments 1 to 9) was dissolved in water. An aqueous PVA solution was applied on an acrylic plate using a metal coater, and then dried at room temperature to obtain a film having a thickness of 100 μm. This was irradiated with ultraviolet rays for 10 minutes with a high-pressure mercury lamp to cause self-crosslinking to obtain a crosslinked PVA film.

(Zinc ion adsorption test) In a 30% potassium hydroxide solution having a zinc ion concentration of 0.1 mol / l, 3 cm × 3
After immersing the films of Experiments 1 to 9 cut into cm and leaving them to stand for 24 hours, each film was washed with pure water to remove zinc ions that were merely attached to the surface and did not form chelate. , Each film is incinerated in a platinum crucible,
The adsorbed zinc ions were extracted, and the amount of zinc ions adsorbed was measured by an atomic absorption method with a fixed volume. The results are shown in Table 1.

[0033]

[Table 1]

(Cadmium ion adsorption test-1) Experiments 1 to 8 were carried out in an aqueous solution having a cadmium ion concentration of 0.1 mol / l.
The cadmium ion adsorption amount was measured in exactly the same manner as in the zinc ion adsorption test, except that each of the films was immersed. The results are also shown in Table 1.

(Cadmium ion adsorption test-2) Zinc ion was used except that the films of Experiments 1 to 3 were immersed in a 30% potassium hydroxide solution having a cadmium ion concentration of 8.9 × 10 ^-5 mol / l. The cadmium ion adsorption amount was measured in exactly the same manner as in the adsorption test. The results are also shown in Table 1.

As can be seen from Table 1, the crosslinked PVA film can adsorb metal, so that it is possible to suppress the deposition of dendritic metal and prevent short circuit due to dendrite.

Example 1 50 parts of a polyethylene resin and 50 parts of a polypropylene resin were separately melted by an extruder and measured at a gear pump speed ratio of 5: 5. Composite spinning and stretching so that the polyethylene resin component becomes the sheath component,
A composite fiber filament having a fineness of 1.5 denier was obtained.

On the other hand, a styrylpyridinium-based residue as shown in Chemical formula 4 (a) is added to monomer units of PVA by 1
A 3% by weight aqueous solution of uncrosslinked PVA in which PVA having a degree of polymerization of 1,700 and a degree of saponification of 88%, having a mol% of 99 mol% of a hydroxyl group capable of forming a chelate, was dissolved in water was obtained.

Next, the composite fiber filament is
After contacting with a roll containing a VA aqueous solution and drying, and adhering 0.5% by weight of PVA as a solid content to the conjugate fiber, the UVA is irradiated with a high-pressure mercury lamp for 1 minute to self-crosslink the PVA. I let it. The composite fiber filament to which the crosslinked PVA was adhered was cut into 51 mm to obtain the alkali-resistant fiber of the present invention.

The alkali resistant fiber 80 thus obtained
% By weight and 20% by weight of a polypropylene-polyethylene core-sheath type composite fiber (1.5 denier, 51 mm) to which no cross-linked PVA was obtained in the same manner as described above, and opened by a carding machine. The fiber web is heat-treated at 130 ° C. to fuse only the polyethylene component, which is the sheath component of the core-sheath composite fiber, with a basis weight of 70 g / m ² and a thickness of 0.2 mm.
Was obtained.

(Example 2) 50% by weight of alkali-resistant fiber
And a polypropylene-polyethylene core-sheath composite fiber (1.5 denier, 51 mm) to which no cross-linked PVA is attached 5
A separator having a basis weight of 70 g / m ² and a thickness of 0.2 mm was obtained in exactly the same manner as in Example 1 except that 0% by weight was blended.

(Comparative Example) Example 1 except that 100% by weight of a polypropylene-polyethylene core-sheath composite fiber (1.5 denier, 51 mm) to which no cross-linked PVA was attached was used.
A nonwoven fabric was obtained in exactly the same manner as described above. Thereafter, a nonionic surfactant was adhered to the nonwoven fabric at a solid content of 0.5% by weight to obtain a separator having a basis weight of 70 g / m ² and a thickness of 0.2 mm.

(Wetability) After the separators of Examples 1 and 2 and Comparative Example were cut into 2 × 15 cm, the separators were immersed in an aqueous solution of potassium hydroxide having a specific gravity of 1.3 for only 0.5 cm and left for 30 minutes. After the elapse, the wettability is evaluated by the liquid absorption height. This test was performed before and after a battery charge / discharge test described later. The results are shown in Table 2.

[0044]

[Table 2]

(Battery charge / discharge test) Using the separators of Examples 1 and 2 and Comparative Example, the capacity of the battery was 1200 mAh.
A nickel-cadmium battery was manufactured. After activating the batteries, each battery was placed in a thermostat at 20 ° C. for 240 minutes.
After charging for 6 hours at mA, rest for 30 minutes, and discharge at 240 mA to a final voltage of 0.8 volts as one cycle.
The number of times until the battery can be charged and discharged is measured. The results are also shown in Table 2.

[0046]

【The invention's effect】

The alkaline battery separator of the present invention contains an alkali-resistant fiber.
A cross-linked PVA, wherein the cross-linked PVA is
Easily decomposed by alkaline electrolytes such as
Not with an alkaline electrolyte such as potassium hydroxide
Has excellent affinity for alkali and liquid retention, and can form and capture ions and chelate before dendritic metal is deposited on the electrode plate during discharging and / or charging. It is difficult for a metal in the form to precipitate, short-circuiting due to dendrite hardly occurs, and can be used for a long time. In addition, the separator of the present invention is an adhesive fiber
Dimensional stability of separator
Is excellent.

As described above, the separator of the present invention is hardly eroded by the electrolytic solution, has excellent liquid retention properties, and has excellent anti-dendritic properties. Therefore, alkaline primary batteries and alkaline secondary batteries using this separator are: It has a long service life.

[Brief description of the drawings]

1A is a schematic cross-sectional view of a splittable conjugate fiber of the present invention. FIG. 1B is a schematic cross-sectional view of another splittable conjugate fiber of the present invention. (D) A schematic sectional view of another dividable conjugate fiber of the present invention (e) A schematic sectional view of another dividable conjugate fiber of the present invention

[Explanation of symbols]

 1 One component 2 Other component

Claims (3)

(57) [Claims] 1. A compound of the general formula (Wherein, R ₁ is a quaternized aromatic nitrogen-containing heterocyclic residue, R ₂ is a hydrogen atom or an alkoxy group, R ₃ is a hydrogen atom or an acyl group, m is 0 or 1, n is 1 to 1) Crosslinking polyvinyl alcohol having a structural unit represented by (natural number 6)
Fiber sheet containing alkali resistant fiber
A separator for an alkaline battery, comprising: 2. A fiber sheet containing an adhesive fiber.
The separation for alkaline batteries according to claim 1, characterized in that:
Ta. 3. An alkaline battery comprising the alkaline battery separator according to claim 1 or 2.