JPS58117637A - Button-type alkaline battery - Google Patents

Abstract

PURPOSE:To increase the preservation performance of a button-type alkaline battery by homogeneously dispersing an amalgamated zinc powder in electrolyte. CONSTITUTION:An amalgamated zinc powder and a gelling agent are homogeneously mixed and dispersed by making the ranges of their grain diameters almost the same. As a result, since any reduction of the reaction surface area as well as any variation of the swelling degree are prevented, a homogeneous battery can be provided by reducing variations in open-circuit voltage, internal resistance and the electric-discharge characteristic. The used amount of the gelling agent is preferred to be 3-6wt% of alkaline electrolyte. When the used amount of the gelling agent is below 2wt% of the alkaline electrolyte, any homogeneously gelled state of the mixture is not achieved due to the difference between the specific gravities of the gelling agent and the amalgamated zinc powder. In contrast, when it is above 6wt% of the alkaline electrolyte, the gelling agent is swollen and combines among itself, and such a phenomenon leads to an increased resistance of the battery, which is not favorable in carrying out electric discharge.

Description

[Detailed Description of the Invention] The present invention provides a method for uniformly dispersing zinc hydrate powder in an electrolyte in alkaline batteries that use an alkaline electrolyte, such as alkaline manganese batteries, mercury batteries, silver oxide batteries, and zinc-air batteries. The purpose of this is to improve storage stability.

The figure shows a commonly used button-type alkaline manganese battery. γ-manganese dioxide powder in inner weight ratio 8
The main component is 6 to 95 wt%, and 6 to 95 wt% of phosphorous graphite powder is added to this.
The positive electrode mixture 1 containing ~15 wt% was placed in the positive electrode container 2.
It is inserted together with the positive electrode ring 3 into the container and compression molded. Then, a gel-like zinc negative electrode 6 having alkali resistance is held and arranged on a sealing plate 7, and the peripheral edge of the sealing plate 7 is tightened with the opening edge of the positive electrode container 2 via a gasket 8, thereby constructing a battery.

In general, in alkaline batteries using zinc as the negative electrode, it is desirable that the negative electrode active material has a maximum reactive surface area, so the negative electrode zinc is used in the form of powder. In order to obtain uniform dispersion of zinc and electrolyte, thickening and
Gelling agents with a large swelling effect, such as CMC and polyvinyl alcohol.

Sodium polyacrylate, polyethylene oxide, etc. have been used.

When mixing a gelling agent with zinc powder and filling a certain amount of it into a negative electrode storage container, uniform mixing and dispersion are difficult due to the particle size distribution of both particles and the differences in individual particles. When manufactured in large quantities, zinc powder ~
The difference in the mixing ratio of the gelling agent results in a reduction in the reaction surface area and variation in the degree of swelling, resulting in differences in the contact area and contact pressure to the current collector. Therefore, various performances such as open-circuit voltage, internal resistance, short-circuit current, discharge performance, etc., vary, making it difficult to provide uniform batteries.

The present invention eliminates the above drawbacks by making the particle size ranges of the frozen zinc powder and the gelling agent almost the same.

The amount of gelling agent used according to the present invention is 3% of the alkaline electrolyte.
~6% by weight is preferred. In other words, if the amount is less than 2% by weight, a uniform gel state cannot be obtained due to the difference in specific gravity between the gelling agent and the frozen zinc powder, while if it is more than 6% by weight, the swollen gelling agents will combine with each other and cause damage to the battery. This increases internal resistance, which is unfavorable during discharge.

The present invention will be explained in detail below.

Table 1 shows the particle size ranges of carboxymethylcellulose powder and the gelling agent used as the gelling agent.

With the above combination, using a cathode mixture weighing machine adjusted with a shutter, the oxidized steel battery 5R44 (outer diameter 11
．． 6■, height 5.4■), the voltage immediately after that,
Table 2 shows the results of examining the internal resistance, 51oΩ discharge characteristics, and discharge characteristics after one year of storage at room temperature.

These results show that the battery of the present invention has small variations in open circuit voltage, internal resistance, and discharge characteristics.

In addition, although CMC was used as a gelling agent in the examples, sodium polyacrylate and polyvinyl alcohol were used.

Similar results were obtained with polyethylene oxide and the like.

Margin below

[Brief explanation of the drawing]

The figure is a half-sectional view of a button-type silver oxide battery in an example of the present invention.

Claims (2)

[Claims] (1) A button-type alkaline battery comprising a negative electrode mixture of hydrated zinc powder, a gelling agent, and an alkaline electrolyte, and having a gelling agent in almost the same particle size range as the hydrated zinc powder. . (2) The particle size range of the frozen zinc powder and gelling agent is 48
The button-type alkaline battery according to claim 1, having a mesh size of 200 meshes to 200 meshes.