JP2798947B2 - Alkaline battery separator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mercury-reduced alkaline battery using a zinc alloy powder containing lead, aluminum, indium or the like as a negative electrode active material, and more particularly to this negative electrode active material and a positive electrode. The present invention relates to improvement of a separator for partitioning a mixture.

<< Conventional Technology >> Since mercury for mercurizing zinc is a kind of pollutant, various zinc alloys for reducing the content of mercury have been developed at present.

Among them, zinc alloys containing lead, aluminum, indium, etc. have been noticed as being a promising material for suppressing the generation of gas and reducing calories.
% Or less of the negative electrode zinc.

However, in the case of a low-mercury alkaline battery using the zinc alloy as the negative electrode active material, there is a problem that the discharge performance is rapidly lowered at a certain load resistance.

This phenomenon is particularly manifested during light load discharge, but as a result of disassembling and examining the inside of these batteries with reduced discharge performance, it was found that an internal short circuit was caused by discharge products. .

The presumed cause of this is that a low-melting zinc alloy containing lead, aluminum, indium, etc., is discharged with a specific current, causing the growth of conductive and unique lead oxide or lead hydroxide crystals. It is believed that the crystals will penetrate the separator, resulting in a short circuit phenomenon.

Therefore, as a countermeasure, there is a method of solving the problem by changing the composition of the zinc alloy, adding an additive having an effect of suppressing the growth of a specific crystal, and a physical method, that is, a fiber forming the separator. There is a method of suppressing the growth of the crystal by closing the gap and sealing the internal short circuit.

The present invention is intended to prevent the internal short circuit phenomenon by devising the latter separator.

However, in order to increase the fiber density of the nonwoven fabric, it was necessary to solve the following problems.

<< Problems to be Solved by the Invention >> While maintaining various characteristics such as electrolyte retention rate and liquid absorption rate required by an alkaline battery separator, a nonwoven fabric having a fiber density as high as possible is stably obtained. Manufacturing has many technical and economic difficulties and has not yet been put to practical use in a safe manner.

Therefore, in order to obtain the same effect as increasing the fiber density of the nonwoven fabric, it is necessary to increase the thickness of the nonwoven fabric or increase the number of times of winding, as a result, and as a result, the thickness of the separator increases. I will.

When the thickness of the separator increases, the filling amount of the negative electrode active material and the positive electrode mixture decreases, so that general performances such as discharge performance and storability are largely reduced.

In addition, cellophane is considered to be used as a separator material instead of the nonwoven fabric. However, when used alone, the absorption rate of the electrolyte is slow, and the electrolyte filled in the separator is quickly absorbed into the positive electrode mixture. However, since the current value immediately after battery assembly becomes unstable or cellophane itself has a high ion permeation resistance, the internal resistance increases and the high-load continuous discharge characteristics deteriorate. Was.

Furthermore, it has also been proposed to use cellophane wound around the nonwoven fabric, but if the electrolyte is injected while both are wound, cellophane will be wrinkled, and the injection cylinder will be clogged. At present, it is difficult to insert, and there is a problem due to a difference in a retention rate and a liquid absorption rate between the two, and at present, it has not been put to practical use.

An object of the present invention is to solve the problem of forming a separator by winding a nonwoven fabric and cellophane, and to provide an alkaline battery separator having no crystal penetration and low ion permeation resistance.

<< Means for Solving the Problems >> In order to achieve the above object, the present invention provides a method for producing
In an alkaline battery in which the following zinc alloy powder is used as a negative electrode active material and the negative electrode active material and the positive electrode mixture are partitioned via a cylindrical separator, the separator is formed by stacking cellophane and a nonwoven fabric on top of each other, The point is that at least three points or perforated cuts are formed on the entire surface of the cellophane, penetrating the front and back of the cellophane, with a length of 10 mm or less and 1 cm ² or less. ing.

The LR6 type alkaline battery according to the present invention has a first
It has the general structure shown in the figure.

In this alkaline battery, the inner peripheral portion of the upper opening of the bottomed cylindrical battery case 1 is crimped to the peripheral flange portion of the negative electrode terminal plate 2 via a sealing gasket 3 by a drawing process, a curling process, or the like, thereby sealing the inside of the battery. doing.

Inside the battery, a current collecting rod 4 whose upper end penetrates the center of the sealing gasket 3 and is electrically connected to the negative electrode terminal plate 2.
And a gelled zinc negative electrode 5 and a positive electrode mixture 6 mainly composed of manganese dioxide are concentrically filled so as to surround the outer periphery of the current collecting rod 4, and the two are separated by a cylindrical separator 7. It constitutes a power generation element.

The gelled zinc negative electrode 5 is obtained by mixing and dispersing a negative electrode active material obtained by calcining a zinc alloy powder in a gelled alkaline electrolyte, and more specifically, adding a trace amount of lead-aluminum-indium to zinc. Yes, its degree of calcining is 1.5%
It is.

The gel electrolyte has a composition comprising a potassium hydroxide solution and a gelling agent such as CMC. The gelled electrolyte is obtained by mixing and dispersing the above-mentioned mercurized zinc alloy powder.

The separator 7 is made of cellophane 8 as shown in FIG.
And the non-woven fabric 9 are pasted together via a glue,
It is formed into a cylindrical shape by winding three times, and a lid 7a is attached to the bottom.

It is to be noted that the two may be simply formed into a cylindrical shape by overlapping each other.

Further, the layer structure may be a double structure of cellophane 8 and nonwoven fabric 9 as shown in the figure, or cellophane 8 as shown in FIG.
May have a three-layer structure in which both sides are bonded in a sandwich state with a nonwoven fabric 9.

The non-woven fabric 9 is made of vinylon and a binder, or vinylon and a cellulosic fiber to which a binder is added.

The cellophane 8 is obtained by coagulating the viscose liquid in a coagulation bath under flow, regenerating the cellulose in a cellulose regeneration bath, desulfurizing, washing with water, and drying.

This thickness is determined by the concentration of the viscose liquid and the amount flowing down. If the thickness exceeds 30 μm, it leads to an increase in internal resistance, and if the thickness is 15 μm or less, stable production is difficult in terms of manufacturing technology. It is desirable that the range be 15 to 30 μm.

A cut that penetrates the front and back of cellophane 8 is formed on the entire surface of cellophane 8 thus obtained.

The cut is formed by passing the raw material of cellophane 8 between rolls provided with a plurality of blades at a predetermined length and interval.
Cuts of predetermined length and intervals of 3 or more points are formed at 1 cm ² and 10 cm or less and 1 cm ² . Note that a point may be used instead of a perforated cut.

If the length of the cuts is too long, the cuts will open or overlap in the wound state, and the desired objectives such as prevention of crystal growth, improvement in electrolyte absorption rate, and reduction in ion passage resistance will not be achieved.

In addition, when the formation density is low, the absorption rate of the electrolytic solution into the mixture becomes low.

Therefore, it is desirable that the length be 10 mm or less, and if the cut is a point, 1 cm ² and 3 or more.

The non-woven fabric 9 has a thickness of 80 to 200 μm obtained by mixing vinylon and pulp via a polyvinyl alcohol binder.
m non-woven fabric.

As a paste used for bonding, for example, an aqueous solution of polyvinyl alcohol, CMC, and an aqueous solution of sodium polyacrylate are used.

<< Effect >> Even if crystals are generated due to the peculiar phenomenon, the penetration phenomenon to the separator can be completely prevented by the interposition of the coating by cellophane.

By forming the cuts in the cellophane, the electrolytic solution filled in the separator is rapidly absorbed into the positive electrode mixture through each cut, and the increase in the internal resistance and the influence on the high-load discharge characteristics are small.

There is no wrinkle due to contraction of cellophane itself at the time of injection due to the cut.

<< Effect of the Invention >> As described above, according to the alkaline battery using the alkaline battery separator according to the present invention, it is possible to prevent a discharge abnormality under special discharge conditions when using a low-melting zinc alloy powder. In addition, a reduction in high-load discharge performance can be prevented.

In addition, there is no hindrance at the time of cylinder injection due to wrinkles, which is a manufacturing defect when cellophane is used, and the injection workability is improved.

<< Embodiment >> Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited only to the following embodiments.

Examples 1 and 2 below and configurations of Comparative Examples 1 to 3
LR6 type batteries were manufactured and their performances were compared and measured. As a result, the results shown in Tables 1 to 4 below were obtained.

Example 1. A cellophane having a thickness of 20 μm was perforated while being alternately shifted by a length of 5 mm, a pitch and an interval in a width direction, and the cellophane was sandwiched therebetween through a polyvinyl alcohol solution. A non-woven fabric was stuck on both sides, and the three-layer structure was formed into a single roll and formed into a cylindrical shape, which was used as a separator to assemble an LR6 type alkaline battery as shown in FIG.

The non-woven fabric is made of 65% vinylon and 20 linter pulp.
%, Polyvinyl alcohol binder 15% composition thickness 14
The thing of 0 μm was used.

The zinc alloy powder used for the gelled zinc negative electrode to be filled in the separator is a zinc alloy powder having a 1.0% calcining ratio, and has a composition of 500 ppm lead, 500 ppm aluminum, 200 p
pm indium, balance zinc.

Example 2 Cellophane having a thickness of 20 μm has a diameter of 0.05 to 0 at 10 points per cm ² .
The same non-woven fabric as in the first embodiment was bonded in a sandwich state to a three-layer structure, and the three-layer structure was single-wound to form a separator. The battery was assembled.

 The other composition is the same as in the first embodiment.

Comparative Example 1. The cellophane had a three-layer structure together with the non-woven fabric in a state where the cellophane was not cut, and this was single-wound to form a separator,
Using this, an LR6 alkaline battery was assembled. Other configurations are the same as in the first and second embodiments.

Comparative Example 2. A commonly used nonwoven fabric was wound three times to form a separator, and an LR6 type alkaline battery was assembled using the separator.

The zinc alloy powder used to fill the inside of the negative electrode was the same as the first and second embodiments, that is, a zinc alloy powder having a 1.0% calorization ratio.

Comparative Example 3. A commonly used alkaline battery having a rate of calcining of 3.
0% powdered zinc was used for the gelled zinc negative electrode.

* The discharge performance was indicated by an index with the performance at the first time of Comparative Example 3 as 100.

As is clear from the results shown in the above tables, Example 1,
In the alkaline battery of No. 2, there is no discharge abnormality under special discharge conditions, and the reduction in high-load discharge performance is small.

In addition, the short-circuit current value immediately after assembly is sufficient, suggesting that the internal electrolyte solution is quickly absorbed by the positive electrode mixture through the separator, and that the increase in internal resistance after storage is small.

On the other hand, in the alkaline battery of Comparative Example 1, as shown in Table 2, a sufficient short-circuit current value immediately after assembly was not obtained.
Further, in the alkaline battery of Comparative Example 2, as shown in Table 1, many abnormal discharges were observed under the special discharge conditions. In the alkaline battery of Comparative Example 3, a short-circuit current value immediately after assembly and a short-circuit current value one month after assembly were sufficiently obtained (see Tables 2 and 3), and abnormal discharge was observed under special discharge conditions. However, as shown in Table 4, the degree of decrease in the discharge characteristics after storage with respect to the initial discharge characteristics was large, as shown in Table 4.
There is a disadvantage that the fiber performance of the discharge characteristics is not sufficient.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an LR6 type alkaline battery applied to the present invention, FIG. 2 is an enlarged sectional view showing a layer structure of a separator, and FIG. 3 is an enlarged sectional view showing another layer structure of a separator. . 5: Gelled zinc negative electrode 6: Positive electrode mixture 7: Separator 8: Cellophane 9: Non-woven fabric

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-4262 (JP, A) JP-A-59-14262 (JP, A) JP-A-51-142637 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) H01M 2 / 16,2 / 18,6 / 06

Claims (1)

(57) [Claims] 1. An alkaline battery in which a zinc alloy powder having a degree of calorification of 1.5% or less is used as a negative electrode active material and the negative electrode active material and the positive electrode mixture are separated via a cylindrical separator, wherein the separator is a cellophane. And a non-woven fabric are overlapped and wound to form a cylindrical shape, and three or more points or perforated cuts of 1 cm ² or less with a length of 10 mm or less penetrating the front and back of the cellophane are formed on the entire surface of the cellophane. A separator for an alkaline battery, wherein a separator is formed.