JP3260932B2 - Alkaline battery separator 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 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]

DISCLOSURE OF THE INVENTION The present invention relates to an alkaline battery having a long service life, which is not easily attacked by an electrolytic solution, is excellent in the retention of the electrolytic solution, and hardly causes a short circuit due to dendrite in which dendritic metal is deposited. And an alkaline battery using the same.

[0009]

Means for Solving the Problems The separator for an alkaline battery of the present invention (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. A hydroentangled nonwoven fabric containing a polyvinyl alcohol (hereinafter sometimes referred to as “PVA”) having a structural unit represented by the following formula (natural number of 6) in a crosslinked state (hereinafter sometimes referred to as “crosslinked PVA”): . When the ultrafine fibers are contained in the constituent fibers of the hydroentangled nonwoven fabric, the separator is more excellent in the retention of the electrolyte and the prevention of dendrite. What
In addition, the hydrophobic part formed by the aldehyde compound
Crosslinked state of polyvinyl alcohol
When included in the separator, flexibility is generated and handleability of the separator is improved.
Up. In addition, the adhesive fibers may be included in the constituent fibers of the hydroentangled nonwoven fabric.
Including fibers improves dimensional stability and improves handling
The quality is improved.

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

[0011]

Since the separator of the present invention contains cross-linked PVA, it is not easily decomposed by an alkaline electrolyte such as potassium hydroxide, can be used for a long time, and has excellent heat resistance. Therefore, it can withstand use under a high temperature state such as trickle charging.

Further, the cross-linked PVA has an affinity for the electrolytic solution and is excellent in the retention of the electrolytic solution. In addition, the fiber orientation of the hydroentangled nonwoven fabric is mainly in the thickness direction.
Since a certain thickness can be maintained against the expansion of the electrode and the like, the separator is more excellent in holding the electrolytic solution.

Furthermore, since the crosslinked PVA has a hydroxyl group capable of forming a chelate with ions before the dendritic metal is deposited on the electrode plate during discharging and / or charging, the crosslinked PVA has a dendritic shape. Metal is less likely to precipitate and short-circuiting due to dendrites is less likely to occur. In addition, ion and chelate are formed,
The trapping of ions has been confirmed by experimental examples described later.

The crosslinked 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, there may be mentioned 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.

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

The hydroxyl group of the 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 of the separator can be improved.

The separator of the present invention has a crosslinked P
A hydroentangled nonwoven fabric containing VA, but the cross-linked P
A nonwoven fabric obtained by hydroentanglement of a fiber web containing fibers to which VA is attached may be used, or a crosslinked PVA may be attached to a nonwoven fabric obtained by hydroentanglement of a fiber web, as in the latter case. If the crosslinked PVA is adhered after the nonwoven fabric is formed, the crosslinked PVA does not peel off by the water flow.

Hereinafter, a case where a crosslinked PVA is adhered after forming a nonwoven fabric will be described based on a manufacturing method.

If the fibers constituting the hydroentangled nonwoven fabric of the present invention are polyolefin fibers, they can be preferably used because they are less likely to be decomposed by an electrolytic solution. Examples of the polyolefin fibers include polyethylene fibers and polypropylene. Polyolefin fibers such as fibers, core-sheath type, side-by-side type, eccentric type, or FIG.
One having a chrysanthemum-like fiber cross-section in which one component 1 is disposed between other components 2 as shown in FIG. 1D, or one component 1 and another component 2 alternate as shown in FIG. Having a fiber cross section laminated in layers, splittable or non-divided polyethylene-
Examples include polypropylene composite fibers. In addition, among the polyolefin-based fibers, if the ultrafine fibers obtained by the melt blow method or the ultrafine fibers obtained by dividing the above-mentioned splittable conjugate fibers, the obtained hydroentangled nonwoven fabric has a large surface area and thus has an affinity for the electrolytic solution. Is easy to work, and the distance between the entanglement points of the fibers is short, and the voids are minute and dense.
This is a separator that can be used for a long period of time because a capillary effect is generated, the retention of the electrolytic solution is excellent, and further, a short circuit due to dendrite can be physically prevented. Among these, if the splittable conjugate fiber is a split ultrafine fiber, it can be split at the same time as entanglement by water flow, so not only is it preferable in production, but the obtained water entangled nonwoven fabric also has excellent strength. Therefore, it is excellent in workability at the time of battery assembly and the like, and can be used more preferably.

The finer the fine fibers, the finer the finer the fibers, the more the capillary effect can be produced and the more the dendrites can be physically prevented. However, if the fine fibers are too fine, the separator becomes less strong. 0.01-0.0.
Preferably it is 4 denier.

In order to improve the dimensional stability of the separator and to further improve the handleability, an adhesive fiber may be included. As this adhesive fiber, for example,
There are polyolefin-based fibers such as all-melted polyethylene fibers and polypropylene fibers, and partially-melted core-sheath, side-by-side, and eccentric polyolefin-based composite fibers. In addition, it is also possible to adhere | attach with the heat bonding component produced | generated from the splittable conjugate fiber which has a heat bonding component.

The fiber web is formed from the fibers as described above. Examples of the method of forming the fiber web include, but are not limited to, a dry method such as a card method and an air-lay method and a wet method.

When the fiber web is formed by the card method, the orientation of the fibers may be unidirectional, the fibers may be oriented so as to intersect with each other by a cross layer, or the layers may be laminated. Among these,
The fiber web containing the fiber web oriented so that the fibers cross each other is likely to be entangled with each other during the subsequent hydroentanglement treatment, so that a hydroentangled nonwoven fabric excellent in strength can be obtained.

The fiber web obtained as described above is subjected to a hydroentanglement treatment. Since the orientation direction of the fibers becomes substantially the thickness direction of the non-woven fabric due to the hydroentanglement treatment, it can withstand the pressure at the time of assembling the battery. This is a separator that can withstand the above pressure and has excellent electrolyte solution retention.

Further, if the entangled fibers are mainly composed of ultrafine fibers, the separator can be made thin, so that the active material can be filled in the battery by the reduced thickness.
The capacity of the battery can be increased.

Examples of the water entanglement treatment having such excellent effects include a nozzle plate having a nozzle diameter of 0.05 to 0.3 mm and a pitch of 0.2 to 3 mm, and a nozzle plate arranged in a line.
Using a nozzle plate with nozzles arranged in two or more rows,
Process at a water pressure of 10 to 300 kg / cm ² . Such a hydroentanglement process need not be performed once, but can be performed two or more times if necessary. Further, the water flow treatment surface need not be only one surface of the fiber web, and both surfaces may be treated.

If the support such as a net or a mesh on which the fiber web is placed has large holes during the hydroentanglement treatment, the resulting separator also has large holes, and a short circuit is likely to occur. Therefore, it is more preferable to use a fine woven net having a mesh size of 60 mesh or more and a perforated plate having a hole-to-hole distance of 0.4 mm or less.

The above-mentioned crosslinked PVA is adhered to the hydroentangled nonwoven fabric thus obtained. As a method of applying the adhesive, if another adhesive or the like is used to attach the cross-linked PVA, the retention of the electrolytic solution by the cross-linked PVA and the prevention of dendrite decrease, so the polyvinyl alcohol solution before cross-linking is sprayed. It is more preferable to carry out self-crosslinking after the adhesion by an impregnation method, a coating method or the like.

The crosslinked PVA is preferably contained in the separator in an amount of 0.5% by weight. If the content is less than 0.5% by weight, the retention of the electrolyte by the crosslinked PVA and the prevention of dendrite are inferior. When this separator is used in a sealed secondary battery, the crosslinked PVA is preferably 10% by weight or less in the separator. If the content exceeds 10% by weight, the mobility of gas generated during charging to other electrodes deteriorates, the internal pressure increases, and there is a risk of rupture. When used in a sealed secondary battery, it is more preferable that 1 to 5% by weight of crosslinked PVA is contained in the separator.

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 composed 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 for 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.

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

[0037]

【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.

[0039]

[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) A 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 cross-linked PVA film can adsorb metals, so that the deposition of dendritic metals can be suppressed, and short-circuits due to dendrites can be prevented.

(Examples 1 to 3) A styrylpyridinium-based residue as shown in Chemical formula 4 (a) was contained in an amount of 1.3 mol% based on the monomer unit of PVA, and a hydroxyl group capable of forming a chelate was 98.7. With a degree of polymerization of 1,700 and a degree of saponification of 8
8% PVA dissolved in water, 13% by weight in uncrosslinked state
A PVA aqueous solution was obtained.

On the other hand, as shown in FIG. 1 (c), a polypropylene component (symbol 2, a circular polypropylene component: 0.04 denier, a petal-shaped polypropylene component:
0.12 denier) and polyethylene component (symbol 1,
0.12 denier), a splittable composite fiber having a fineness of 2 denier and a fiber length of 38 mm having a chrysanthemum flower-like cross-sectional shape was opened by a carding machine to obtain a fiber web in which the fibers crossed by a cross layer. . This fiber web was placed on an 80-mesh plain weave net, and the nozzle diameter was 0.13 mm.
From a nozzle plate with a pitch of 0.6mm, water pressure of 120kg / cm
² water flow, entangled by the action increments twice from both sides, basis weight 55 g / m ^2, to obtain a thickness of 0.15mm of hydroentangled nonwoven fabric.

With respect to this hydroentangled nonwoven fabric, the PVA
The aqueous solution was impregnated with 0.6, 1.7, and 2.9 g / m ² (in the order of Examples 1, 2, and 3) as solids, dried, and then irradiated with ultraviolet light for 3 minutes using a high-pressure mercury lamp, and PVA was self-contained. Crosslinking was performed to obtain the separator of the present invention.

(Comparative Example) A hydroentangled nonwoven fabric having a basis weight of 55 g / m ² and a thickness of 0.15 mm to which no crosslinked PVA was adhered and obtained in the same manner as in Example 1 was used as a separator.

(Measurement of Liquid Retention under Pressure) The weight (W) of the separators of Examples 1 to 3 and Comparative Example cut to a diameter of 50 mm.
After measuring ₀ ), the separator is immersed in a potassium hydroxide solution having a specific gravity of 1.3 for 1 hour so that the air in the separator is replaced with the potassium hydroxide solution, and the potassium hydroxide solution is retained. Thereafter, the separator is sandwiched between three filter papers (diameter 50 mm), three at a time, and a force of 1 ton is applied to the separator by a pressure pump.
After operating for 2 seconds, the weight (W ₁ ) of the separator is measured. Then, the pressurized liquid holding ratio is obtained by the following equation. As a result, the liquid pressure retention rates of Examples 1 to 3 and Comparative Example were 18.8, 23.0, 24.1, and 15.9%, respectively.

[0048]

As the separator for an alkaline battery of the present invention contains crosslinked PVA, it is not easily decomposed by an alkaline electrolyte such as potassium hydroxide and can be used for a long time.

Further, the crosslinked PVA has an affinity for the electrolytic solution and is excellent in the retention of the electrolytic solution. In addition, in the hydroentangled nonwoven fabric, the orientation direction of the fibers is the thickness direction, so that the Since the separator can maintain a certain thickness against expansion and the like, the separator is more excellent in holding the electrolytic solution.

Furthermore, since the crosslinked PVA has a hydroxyl group capable of forming a chelate with ions before the dendritic metal is deposited on the electrode plate during discharging and / or charging, the crosslinked PVA has a dendritic shape. Metal is less likely to precipitate and short-circuiting due to dendrites is less likely to occur.

When the ultrafine fibers are contained in the constituent fibers of the hydroentangled nonwoven fabric of the present invention, it is more excellent in the retention of the electrolytic solution,
A separator with excellent dendrite prevention properties. In addition,
Hydrophobic part formed by aldehyde compound partially
In the crosslinked state of the polyvinyl alcohol
In addition, flexibility is generated, and the handleability of the separator is improved.
You. In addition, adhesive fibers are included in the constituent fibers of the hydroentangled nonwoven fabric.
When included, dimensional stability is improved and handling is easier.
Is improved.

As described above, the separator of the present invention is hardly attacked by the electrolytic solution, is excellent in the retention of the electrolytic solution, and is excellent in the prevention of dendrite. 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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 2/16 H01M 6/06 H01M 10/24 H01M 10/28

Claims (5)

(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, and n is 1 to 1. Crosslinking polyvinyl alcohol having a structural unit represented by (natural number 6)
A separator for an alkaline battery, comprising a non-woven fabric entangled in water, wherein the separator is included in a state in which the non-woven fabric is contained. 2. The separator for an alkaline battery according to claim 1, wherein ultrafine fibers are contained in the constituent fibers of the hydroentangled nonwoven fabric. 3. A hydrophobic substance formed by an aldehyde compound.
Crosslinking the polyvinyl alcohol partially having a portion
Claim 1 or Claim characterized in that it is included in the state
Item 3. An alkaline battery separator according to Item 2. 4. An adhesive fiber in the constituent fibers of the hydroentangled nonwoven fabric.
The fiber according to any one of claims 1 to 3, wherein a fiber is contained.
An alkaline battery separator according to any of the preceding claims. 5. An alkaline battery using the separator according to claim 1 .