JPS63237366A - Manufacturing method of alkaline zinc storage battery - Google Patents

Abstract

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

Description

D) Industrial Field of Application The present invention relates to a method for producing an alkaline zinc storage battery using zinc as a negative electrode active material, such as a nickel-zinc storage battery or a silver-zinc storage battery.

(b) Conventional technologyAlkaline M batteries using zinc as the negative electrode active material have advantages such as high energy density, high operating voltage, and excellent economic efficiency, but have the disadvantage of short cycle life. There is. The reason for this is that during discharge, zinc is eluted into the alkaline electrolyte as zincate ions, and during charging, these zincate ions are deposited as metal zinc in a dendritic form on the surface of the zinc negative electrode. This is due to zinc growing and penetrating the separator and coming into contact with the positive electrode, causing an internal short circuit.

Various separator materials have been studied to suppress the growth of this dendritic zinc, but those made of one separator do not have a sufficient suppressive effect, so those made of several separators or several types have been studied. There have been many proposals to make the system more structured.

For example, Japanese Patent Application Laid-Open No. 57-197757 discloses that the amount of free electrolyte is limited so that the amount of electrolyte contained in the separator in contact with the zinc negative electrode is smaller than the amount of electrolyte in the separator in contact with the positive electrode. This is disclosed. This method can suppress the escape of zincate ions, reduce internal short circuits with the positive electrode due to dendritic zinc growth, and alleviate deformation of the zinc negative electrode.

(c) Problems to be solved by the invention However, if the multilayer separator used in the invention described in JP-A-57-197757 and the like is used and the amount of electrolyte is limited, the electrolyte will not be present between the positive and negative electrodes. becomes difficult to distribute uniformly. Then, the electrolyte is distributed unevenly and φ
As a result, the current distribution between the positive and negative electrodes becomes uneven during charging and discharging, and as the charging and discharging cycles progress, the shape of the zinc negative electrode becomes noticeably deformed. Dryout occurs. As a result, shape deformation and growth of dendritic zinc are accelerated, resulting in a rapid decrease in battery capacity. Furthermore, variations in battery cycle life also increase, making it difficult to obtain stable battery performance.

B) Means for Solving the Problems The method for producing an alkaline zinc storage battery of the present invention involves impregnating a multilayer separator interposed between the positive and negative electrodes with water, and then removing the electrodes formed by the positive and negative electrodes and the multilayer separator in a predetermined state. After constructing the body and inserting the front d-pi electrode body into the battery case, the electrolyte is injected.

(E) Function: Wet the multilayer separator with water beforehand, and
When an electrode body consisting of a negative electrode and a multilayer separator is constructed and then an electrolyte is injected, the electrolyte dissolved in the electrolyte gradually diffuses from the point where the electrolyte and water come into contact. Immediately after the electrolyte is injected, a large electrolyte concentration gradient occurs between the part of the multilayer separator that is in contact with the injected electrolyte and the other parts, and this concentration gradient disappears after enough time has passed. It is thought that this will be resolved and a uniform concentration distribution will result. As a result, the portion of the multilayer separator that has been pre-wetted with water becomes fully impregnated with electrolyte. Therefore, non-uniform distribution of the electrolyte between the electrodes is suppressed. If the multilayer separator is not kept impregnated with water, the viscosity of the electrolyte itself is high, and the amount of injection is limited, making it difficult to distribute the electrolyte uniformly between the electrodes. .

(f) Example Active materials: 85% by weight of zinc oxide powder, 10% by weight of metallic zinc powder, and 5% by weight of cadmium oxide powder for increasing the hydrogen overvoltage were added to a mixed powder with water and polytetrafluorocarbon powder. Ethylene dispersion was added and kneaded to obtain an active material paste. This active material paste was pressed onto both sides of a conductive core made of nickel mesh to obtain a zinc negative electrode.

On the other hand, polypropylene microporous film (25 μ) 2
1 piece of nylon non-woven fabric (120μ) with high liquid retention properties
After immersing a multilayer separator composed of a single sheet in pure water to remove all excess moisture, the zinc negative electrode and a known sintered nickel positive electrode are combined to form a spiral electrode body T-structure,
The entire electrode assembly was inserted into a battery case, which is a battery case. A 36% by weight KOH aqueous solution saturated with zinc oxide was poured into this,
Completely sealed, sealed, nominal capacity! A 2000 mAh battery was obtained. Here, since the KOH aqueous solution used as the electrolytic solution is a multilayer separator impregnated with water, it has a slightly higher gold concentration than the electrolytic solution normally used.

This battery was designated as Invention Battery A.

As a comparative example, comparative battery B1F is the same as battery A except that the multilayer separator was not impregnated with water and a 30% by weight KOH aqueous solution saturated with zinc oxide was injected. :Obtained. Note that in the present invention battery A and the comparative battery B, the electrolyte concentration and the electrolyte t in each battery are the same.

These invention batteries A, ratio 4 [! A charge/discharge cycle test was performed under the condition that all two batteries B were charged at a current rate of 4 hours for 5 hours and then discharged at a current rate of 1 hour until the battery voltage reached t3V, and the cycle characteristics were compared. Here, when the battery voltage of t3V cannot be maintained for 42 minutes during discharging, that is, the battery discharge capacity is 7V of the nominal capacity.
The cycle life of the battery was defined as the point where it became 0% or less.

The results are shown in the figure. It is understood that this CD battery according to the present invention has excellent cycle characteristics as compared to comparative battery B, and the variation in cycle characteristics is also small. therefore,
It was understood that the battery A obtained by the manufacturing method of the present invention has a long cycle life and stable quality.

Furthermore, in the examples, the multilayer separator is pre-impregnated with a solution that is less corrosive than the conventional electrolyte that is commonly used, so there is no need to worry about damaging the battery manufacturing equipment. do not have. In other words, the 9-water used in the present invention is a low-e4, which has an extremely low degree of corrosion.
It is also possible to use a reverse electrolyte.

(G) Effects of the Invention According to the production method of the present invention, an alkaline zinc & IA pond with stable cycle characteristics of one quality can be obtained, so its industrial value is extremely large.

[Brief explanation of drawings]

The figure is a comparison diagram of cycle characteristics of batteries. A: Battery of the present invention, B: Comparative battery.

Claims (1)

[Claims] (1) After impregnating the multilayer separator interposed between the positive and negative electrodes with water, construct an electrode body consisting of the positive and negative electrodes and the multilayer separator, and insert the electrode body into a battery container. A method for manufacturing an alkaline zinc storage battery, characterized by performing liquid injection.