JPH01173567A - Alkaline cell - Google Patents

Abstract

PURPOSE:To improve the cell performance by using a separator overlappingly constituted of multiple sheets of the integrated paper with a double structure consisting of a layer of beaten natural fibers with increased density and a layer of synthetic fibers. CONSTITUTION:A separator 7 overlappingly constituted of multiple sheets of the integral paper with a double structure consisting of a layer of beaten natural fibers made of alkali-insoluble cotton or pulp and having increased density and a layer of synthetic fibers is used. The separator can be thereby constituted thin, and the cell performance can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an alkaline battery having an improved separator structure.

[Prior Art] Alkaline batteries are excellent in heavy load discharge, and there is a tendency for demand for small batteries to increase more and more in various devices such as strobes and cassette recorders. Against this background, there is a demand for further miniaturization and higher density, so the function of the separator has become very important.

This is because in heavy load discharge, it is safe to make the electrode reaction speed faster, and the configuration of the separator used has a great influence.

In order to improve ionic conductivity, a cylindrical separator with a bottom is usually used, which is made of pulp or paper mixed with rayon fiber and vinylon, which has excellent lyophilicity and liquid-holding ability, to maintain liquid-holding ability and strength. A paper made of three or more sheets of mixed paper pasted together was commonly used.

The fiber thickness of conventionally used separators is 10 μm.
The nonwoven fabric is made up of entangled relatively rough fibers with an approximate density of about 0.2 g/cc. The separator has a thickness of about 140 to 180+ m and is stacked in three to four layers to form a cylindrical separator with a bottom.

When this separator is fused with an electrolytic solution, it is sufficiently impregnated with the liquid and each fiber swells, so the thickness of the separator sheet is about 200 μm, and in the case of a stack of 3 separators, the thickness of the separator sheet is about 200 μm.
It swells to about 00Pm.

As a result, the distance between the positive and negative electrodes increases, resulting in a decrease in short-circuit current value.Therefore, when used in a strobe that requires continuous light emission, there is a problem in that the required characteristics cannot be obtained sufficiently.

Therefore, if the separator was made thin enough or double-wound and triple-wound to be sufficient for short-circuit current and strobe use, there was a problem that the open circuit voltage of the battery would drop when stored for a long period of time.

[Problems to be Solved by the Invention] As described in section 5, in conventional alkaline batteries, the separator is not suitable, so sufficient characteristics cannot be obtained and there are problems such as a decrease in open circuit voltage.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide an alkaline battery with sufficient discharge characteristics and high reliability.

[Means and effects for solving the problems] In order to achieve the above object, the alkaline battery of the present invention is made of a dual-structure integrated paper having a layer of beaten natural fibers to increase the density and a layer of synthetic fibers. It is characterized by the use of a separator made up of multiple stacked layers.

With this configuration, since the beaten natural fiber side has a high density, the thickness of the separator can be made thinner than conventional ones, without impairing battery performance.In addition, the increased density increases the strength. This improves work efficiency.

[Example code] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The accompanying drawings show an embodiment of the invention configured as an alkaline manganese battery. In the figure, reference numeral 1 denotes a cap that also serves as a negative electrode terminal, and a current collector 2 is resistance welded to the center thereof, passes through the center of a gasket 3, and is further inserted into a negative electrode zinc 4. The material for Gasget 3 is nylon 6.
is used.

The negative electrode zinc 4 is made by amalgamating zinc grains of about 150+ m with 3% mercury and dispersing them in an electrolytic solution with a gelling agent. Reference numeral 5 denotes a positive electrode mainly made of manganese dioxide, which is in contact with and electrically connected to a positive electrode can 6 made of iron plated with nickel.

A separator 7 made of nonwoven fabric is provided on the inner surface of the positive electrode 5 to prevent contact between the negative electrode zinc 4 and the positive electrode 5, and the separator 7 has excellent ionic conductivity by being impregnated with an electrolyte. It's Nara.

A sealing plate 8 is disposed at the opening of the positive electrode can 6, and the opening end of the positive electrode can 6 is caulked to seal the opening in an airtight and liquid-tight manner.

The separator 7 used in this embodiment has a thickness of approximately 40 μm and is made of natural fiber Kotton crushed with a beater and refined into fibers tO, IPm or less.
A layer of beaten natural fiber with a thickness of 60 μm and a layer of a nonwoven fabric with a density of 0.2 g/cc made of vinylon fiber with a density of 0.5 denier are integrally constructed. The separator is processed into a cylindrical shape, and then a bottom is formed to obtain a cylindrical separator with a bottom. Note that some of the finest beaten natural fibers reach 0.01 μm.

Further, consideration is given to placing vinylon, which is a synthetic fiber and has excellent chemical resistance, on the side of the separator 7 that comes into contact with the positive electrode can 5.

The natural fiber layer inside the separator is made of α-cellulose, which has excellent alkali resistance and is made into fine particles using a pulp beater, and has a fiber density of 0.6 g/ cc and sometimes 0.
It can be increased to 8 g/cc. In addition, the fiber density when not beaten is about 0.13 to 0.3 g/ccζ
Not too much.

When using a separator formed from a double-structured structure having such a layer on one side, the degree of swelling after contacting and impregnating with electrolyte during battery manufacturing is less than when it is not beaten. There is little deformation of the separator dimensions,
Therefore, in a cylindrical battery, the effect of swelling of the separator on the internal volume of the battery is small, and the distance between the positive and negative electrodes is shorter than that of conventional batteries, and the beaten fiber side is denser. It has now become clear that the conventional triple separator configuration can function satisfactorily with double separators.

In the case of a conventional triple separator, the degree of swelling is 60.
The thickness of the double separator of this example could be reduced from about 0 μm to about 240 μm.

Note that if a separator is made of paper made from beaten natural fibers, and the thickness is suitable for mechanical handling required during battery manufacturing, for example, about 1100p, the fiber density is high, so ion permeation within the battery is not sufficient and the internal This is undesirable because resistance increases.

In the case of this example, since it has a double structure of beaten natural fiber and vinylon, when the thickness of one sheet is about 1100p, it can withstand mechanical handling and suppress the increase in internal resistance. It has its features.

For reference, 40Pm made of cotton-beaten natural fiber.
80+ layer and 1.0 denier vinylon fiber.
A separator according to the present invention, which is a two-layer winding made by processing a double-structured nonwoven fabric with m layers into a cylinder with a bottom, and for comparison, 30% unbeaten cotton fiber and 70% 10 vinyl fiber were dispersed and mixed in water. The characteristics of the double-wrap and triple-wrap made of paper-made nonwoven fabric are as follows. Table 1 is 40°C
Table 2 shows the change in the short-circuit current when one day has passed since manufacture.

Table 1 ζ Table 2 Table 1 ζ According to this, the product according to the present invention has a higher open circuit voltage and less change than the conventional product, and according to Table 2, the product according to the present invention has a higher open circuit voltage than the conventional product. It is clear that the short circuit current is large compared to the product.

In addition, in this invention, when natural fibers such as cotton or pulp are beaten to obtain a high density, the density of the layer of beaten fibers must be 0.4 g/cc or more, and is about 0.8 g/cc. If the density is higher than that, ion permeation becomes poor when used as a battery, resulting in a decrease in current. It has been found that the thickness of this layer is not appropriate if it is thinner than 40 am because pinholes are formed, and if it is more than 100 mm it is not appropriate because the resistance value becomes high.

In addition, when using a cylinder with a bottom as a separator, it is desirable for the bottom and the cylinder to be made of the same material in terms of work efficiency.
Since the bottom part is not a place where a battery reaction takes place, a material mainly having insulating properties, such as a polyethylene sheet, may be used.

Vinylon is suitable as the synthetic fiber, but polypropylene, polyethylene, nylon, etc., which have strong alkali resistance, can also be used.

Also, mixing natural fibers such as cotton or rayon or their crocodile conductors into the synthetic fiber layer will improve the lyophilic property and be effective, but the amount should be less than 50%.Storage reliability desirable to maintain.

[Effects of the invention] According to this invention, the separator is constructed by stacking multiple sheets of double-structure integral paper consisting of a layer with increased density by beating and a layer of synthetic fibers, so the separator can be constructed thinly. A highly reliable battery can be obtained without impairing battery performance.

Furthermore, since the strength of the integrated paper increases with the increase in density, it can be made excellent in terms of workability.

[Brief explanation of the drawing]

The figure below is a longitudinal cross-sectional view of one embodiment of the present invention.

Claims (4)

[Claims] (1) An alkaline battery characterized by using a separator constructed by stacking multiple sheets of double-structure integral paper consisting of a layer of beaten natural fibers with increased density and a layer of synthetic fibers. (2) The alkaline battery according to claim 1, wherein the natural fiber is alkali-insoluble cotton or pulp. (3) The alkaline battery according to claim 1, wherein the synthetic fiber layer contains 50% or more of vinylon. (4) The natural fiber layer has a density of 0.4 to 0.8 g/cc and a thickness of 15 to 80 μm, and the synthetic fiber layer has a density of 0.18
3. The alkaline battery according to claim 1 or 2, wherein the alkaline battery has a thickness of 40 to 100 μm at ~0.3 g/cc, and a total thickness of both layers is 160 μm or less. Potash battery.