JPH01105457A - alkaline zinc storage battery - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to alkaline zinc storage batteries using zinc as a negative electrode active material, such as nickel-zinc batteries and silver-zinc batteries.

[Prior art]

Such alkaline zinc storage batteries have various advantages such as high energy density, high operating voltage, and excellent economic efficiency, but have the disadvantage of short cycle life. The reason for shortening the cycle life is that zinc in the negative electrode dissolves in the electrolyte during discharge, and during charging, this deposits into dendritic zinc or spongy zinc that easily falls off, causing internal short circuits or deformation of the negative electrode. It is believed that there is a point in doing so.

In order to eliminate such drawbacks, the Special Publication No. 57-19775
As disclosed in Publication No. 7, etc., a multilayer separator consisting of a microporous membrane on the zinc negative electrode side and a nonwoven or woven fabric on the positive electrode side is provided between the two electrodes to form an electrode group. An alkaline zinc storage battery has been proposed. According to such an alkaline zinc storage battery, the presence of the multilayer separator suppresses the escape of zincate ions, thereby suppressing the internal short circuit or deformation of the negative electrode. In order to further ensure the above-mentioned effects, the microporous membrane usually has a structure in which a plurality of microporous films are stacked one on top of the other.

In addition, since the microporous film is originally hydrophobic,
The microporous film is treated with a surfactant to impart hydrophilicity, thereby imparting the microporous membrane with the hydrophilicity necessary for electrode reaction.

[Problem that the invention seeks to solve]

In such conventional alkaline zinc storage batteries, electrolyte tends to accumulate in the gaps formed between stacked microporous films, resulting in uneven electrolyte distribution, which causes the above-mentioned problems. There is a problem in that the deterrent effect against internal short circuits and the like is insufficient.

In addition, in cylindrical batteries formed by winding up an electrode group, the wrinkles that occur as a result of winding up form large gaps in which the electrolyte is particularly likely to accumulate, so the above-mentioned problem is even more pronounced. becomes.

In addition, in the alkaline zinc storage battery, the surfactant applied to the microporous film is eluted and acts as an inhibitor to the charging reaction of the zinc negative electrode, so that the charging voltage increases and the negative electrode capacity increases. As a result,
A problem arises in that the battery capacity decreases significantly.

The present invention has been made in view of the above circumstances, and is an alkaline zinc storage battery that can solve the above-mentioned problems, that is, it has a cycle life that can sufficiently suppress internal short circuits and reduce the decrease in battery capacity as much as possible. Aims to provide a long alkaline zinc storage battery.

[Means for solving problems]

In the alkaline zinc storage battery according to the present invention, a multilayer separator is provided between a zinc negative electrode and a positive electrode, in which a hydrophilic microporous membrane is disposed on the zinc negative electrode side and a fibrous body is disposed on the positive electrode side. In the alkaline zinc storage battery constituting the electrode group, a plurality of microporous films including a microporous film not imparted with hydrophilicity are combined with at least one of the microporous films not imparted with hydrophilicity. The microporous membrane body is integrally formed by laminating them so as to form an outer surface, and the microporous membrane body faces the zinc negative electrode through the microporous film that has not been imparted with hydrophilicity. It is characterized by being arranged to encourage people.

[Effect]

In such an alkaline zinc storage battery, since the microporous membrane has an integrated structure by laminating a plurality of microporous films, there is no gap between the microporous films. As a result, non-uniformity of the electrolyte, which has been a problem in the past, is suppressed.

In addition, since the microporous membrane body is arranged so that the microporous film not imparted with hydrophilicity faces the negative electrode, the presence of the microporous film not imparted with hydrophilicity The surfactant eluted from the hydrophilic microporous film is prevented from acting as an inhibitor to the charging reaction of the zinc negative electrode.

〔Example〕

The present invention will be described in detail below based on drawings showing embodiments thereof.

FIG. 1 is a vertical cross-sectional view schematically showing an example of an electrode group of an alkaline zinc storage battery according to the present invention. In the figure, 1 indicates a zinc negative electrode, and the zinc negative electrode 1 is made of 80% by weight zinc oxide. , 10 weight percent zinc, 5 weight percent cadmium oxide, and 5 weight percent polytetrafluoroethylene dispersion. Further, 2 is a positive electrode consisting of a sintered nickel electrode containing nickel hydroxide. As the electrolytic solution for the alkaline zinc storage battery according to the present invention, an IM concentration of zinc oxide dissolved in a 9N potassium hydroxide solution was used.

The electrode group is constructed by providing a multilayer separator 3 between the zinc negative electrode 1 and the positive electrode 2, and the multilayer separator 3 is a microporous membrane having hydrophilicity necessary for electrode reaction. The body 31 is placed on the zinc negative electrode 1 side, while the nylon nonwoven fabric 32 is placed on the positive electrode 2 side. Further, the microporous film body 31 heats the microporous film 31a that has been imparted with hydrophilicity by applying a surfactant and the microporous film 31b that has not been imparted with hydrophilicity. They are integrally formed by laminating them using a welding method, an adhesive bonding method, or the like. Therefore, the microporous membrane 31 exhibits hydrophilicity as a whole. Moreover, the microporous film body 31 is a microporous film 31b that is not imparted with hydrophilicity.
The zinc negative electrode 1 is arranged so as to face the zinc negative electrode 1.

In such an alkaline zinc storage battery, since the microporous membrane 31 has an integrated structure by laminating two microporous films 31a and 31b, the microporous film 31a, Since no gap is formed between the electrodes 31b, non-uniformity of the electrolytic solution, which has been a problem in the past, is suppressed.

In addition, the microporous membrane 31 is arranged so that the microporous film 31b to which hydrophilicity has not been imparted is faced to the zinc negative electrode 1; The presence of 31b prevents the surfactant eluted from the hydrophilic microporous film 31a from acting as an inhibitor to the charging reaction of the zinc negative electrode 1.

Therefore, when using the above-mentioned alkaline zinc storage battery, the electrolyte is uniformly distributed, internal short circuits etc. are sufficiently suppressed, and the surfactant eluted from the microporous film imparted with hydrophilicity. is suppressed from acting as an inhibitor during the charging reaction, and the decrease in battery capacity can be suppressed as much as possible.

Next, the results of comparing the change in battery capacity of the above-mentioned alkaline zinc storage battery (hereinafter referred to as the battery of the present invention) with that of the conventional alkaline zinc storage battery (hereinafter referred to as the comparative battery) will be explained.

The structure of the electrode group of the comparative battery is completely the same as that of the above-described battery of the present invention, except for the microporous membrane portion. The microporous membrane in the electrode group of the comparative battery is
Two microporous films imparted with hydrophilic properties are simply arranged side by side without being laminated together. The electrode group of the above-described battery of the present invention and the electrode group of the comparative battery were each wound to form a cylindrical battery with a nominal capacity of 700++ Ah. Ten such batteries were prepared for each of the batteries of the present invention and comparative batteries.

All of the batteries thus created were charged at 15 A for 5 hours and then discharged at 150 mA until the battery voltage was 1.3.
A continuous cycle test was conducted under charging/discharging conditions in which discharging was stopped when v was reached.

The results are shown in FIG. In other words, Figure 2 is a graph that shows the relationship between the number of cycles on the horizontal axis and the battery capacity on the vertical axis. The results of the invention battery are shown and 2
The results of the comparison battery are shown by regions whose upper and lower limits are defined by broken lines in the book. As is clear from this figure, it can be seen that the battery of the present invention suppresses a decrease in battery capacity to a lesser extent than the comparative battery, and it can be confirmed that the battery of the present invention has an improved cycle life.

In the above embodiment, the multilayer separator 3 is made of the microporous membrane 31 and the nylon nonwoven fabric 32, but the nylon nonwoven fabric 32 can be replaced by other nonwoven fabric or woven fabric. In addition, although the microporous membrane 31 is formed by laminating two microporous films 31a and 31b, it may also be a structure in which three or more microporous films are laminated and integrated. good. However, the microporous film to which hydrophilicity is not imparted needs to be placed so as to face the negative electrode.

〔effect〕

As detailed above, according to the present invention, internal short circuits, etc. are sufficiently suppressed, and the decrease in battery capacity is suppressed as much as possible.
An excellent alkaline zinc storage battery with a long cycle life can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view schematically showing an electrode group of an alkaline zinc storage battery according to the present invention, and Fig. 2 compares and contrasts the alkaline zinc storage battery according to the present invention and a conventional alkaline zinc storage battery in terms of changes in battery capacity. It is a graph. 1... Zinc negative electrode 2... Positive electrode 3... Multilayer separator 31... Microporous membrane body 31a... Microporous film imparted with hydrophilicity 32... Nonwoven fabric 31b...
・Microporous film with no hydrophilic properties

Claims (1)

[Claims] 1. By providing a multilayer separator between a zinc negative electrode and a positive electrode, in which a hydrophilic microporous membrane is disposed on the zinc negative electrode side and a fibrous body is disposed on the positive electrode side. , in an alkaline zinc storage battery constituting an electrode group, a plurality of microporous films including a microporous film not imparted with hydrophilicity are arranged so that the microporous film not imparted with hydrophilicity is attached to at least one outer surface. The microporous membrane body is integrally formed by laminating them so as to form a structure, and the microporous membrane body is made to face the zinc negative electrode through the microporous film that is not imparted with hydrophilicity. An alkaline zinc storage battery characterized by being arranged as follows.