JP2832018B2 - Method for producing negative electrode for alkaline battery - Google Patents

Description

The present invention relates to an improvement in a method for manufacturing a negative electrode for an alkaline battery in which zinc powder is dispersed in an alkaline electrolyte.

<< Conventional Technology >> A gelled negative electrode used in an alkaline battery is obtained by gelling an alkaline electrolyte such as an aqueous potassium hydroxide solution with a zinc powder and a gelling agent. As a gelling agent, carboxymethyl cellulose (CMC), sodium polyacrylate, polyacrylic acid, etc., alone or
More than one species are mixed and used. Specific procedures for obtaining a gelled negative electrode include wet mixing and dry mixing.

In the wet mixing, a fine powder of a gelling agent is directly added to an alkaline electrolyte having a predetermined concentration, and the mixture is stirred and mixed to obtain a gel electrolyte, and zinc powder is mixed and dispersed therein.

In dry mixing, after a powdery gelling agent and granular zinc are mixed in advance, an alkaline electrolyte is added thereto, followed by stirring and mixing.

<< Problems to be Solved by the Invention >> According to the above-mentioned wet mixing, when the powdery gelling agent is added to and mixed with the alkaline electrolyte, the gelling agent particles are likely to be formed if they are dispersed in a random manner. It is necessary to stir the surface for solvation and obtain a uniform gel electrolyte for a long time, and this stirring process is a major factor that hinders shortening of the negative electrode manufacturing time. Had become.

In the above-mentioned dry mixing, since the powdered gelling agent and the particulate zinc are mixed and then added to the alkaline electrolyte, it is difficult to become an extreme mamako like a wet mixing, and it is 1/2 of the wet mixing.
A gel negative electrode can be manufactured with a stirring time of about 1/3. However, in dry mixing, the surface of zinc particles is likely to be covered with a gelling agent that has not sufficiently penetrated the alkaline electrolyte (the alkaline electrolyte does not easily penetrate the gelling agent attached to the surface of the zinc particles). The internal resistance of the battery increases,
There is a disadvantage that the discharge performance is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a manufacturing method capable of shortening the stirring time and dispersing zinc powder in a gel electrolyte in a favorable state. Is to provide.

<< Means for Solving the Problems >> Therefore, in the present invention, after adding a gelling agent to water to which a fluorocarbon having an ether bond is added and mixing,
An alkaline electrolyte was added thereto, followed by stirring and mixing to obtain a gel electrolyte, in which zinc powder was dispersed.

<Action> Fluorocarbon having an ether bond is a kind of surfactant, and when a fine powder gelling agent is added to water containing the same and mixed, and then an alkaline electrolyte is added and mixed with stirring, the surfactant is used. The action of the activator makes it easier for the gelling agent to be dispersed in the alkaline electrolyte, so that a uniform gel electrolyte can be obtained in a short stirring step without generating the above-mentioned mamako. Thereafter, zinc powder is added to the gel electrolyte and mixed and dispersed in the same manner as in conventional wet mixing.

<< Example >> As a fluorocarbon having an ether bond, Zonyl (trade name, manufactured by DuPont) is used. As a gelling agent, polyacrylic acid (trade name: Junron PW-
150). The mixing procedure is as follows.

The zonil is added to 21% by weight of water. The amount of zonyl added will be described later.

2% by weight of a fine powder gelling agent in water containing the zonil
Add and mix.

The above water + zonil + gelling agent
% Aqueous solution at a ratio of 77% by weight, and well mixed with stirring. Thus, a gel electrolyte solution is obtained.

A predetermined amount of zinc powder is added to the gel electrolyte and mixed.
Disperse.

According to the production method of the present invention by wet mixing to which a fluorocarbon (trade name: Zonyl) is added, as in the case of the conventional wet mixing, as in the case of the conventional dry mixing.
It is possible to obtain a uniform gelled negative electrode with no agitation with a stirring time of 1/2 to 1/3. Also, as in the case of the conventional wet mixing, the pre-gelled electrolytic solution will adhere to the surface of the zinc powder. The surface is never covered.

In addition, the addition amount of the fluorocarbon is desirably 1.0% by weight or less based on the gelling agent. Even if more fluorocarbon was added, the effect of shortening the stirring time was not so large, and it was confirmed that the discharge capacity tended to decrease by adding more fluorocarbon than necessary. Therefore, the smaller the amount of fluorocarbon added, the better the stirring and mixing time can be sufficiently reduced.

<< Effects of the Invention >> As described in detail above, according to the method for manufacturing a negative electrode for an alkaline battery according to the present invention, the surface of the zinc particles does not sufficiently penetrate the alkaline electrolyte as in conventional dry mixing. There is no inconvenience of being covered with the gelling agent (as a result, the discharge performance of the battery is reduced), and a uniform gel without lumps can be obtained in a stirring step much shorter than the conventional wet mixing. Therefore, by adopting this method, an alkaline battery having good performance can be efficiently produced.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Kiyohide Tsutsui 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd. (56) References JP-A-49-4131 (JP, A) ( 58) Surveyed field (Int.Cl. ⁶ , DB name) H01M 4/06-4/12 H01M 6/22

Claims (2)

(57) [Claims] 1. A gelling agent is added to and mixed with water to which a fluorocarbon having an ether bond is added, and then an alkaline electrolyte is added thereto, followed by stirring and mixing to obtain a gel electrolyte, and zinc powder is dispersed therein. A method for producing a negative electrode for an alkaline battery. 2. The method according to claim 1, wherein the amount of the fluorocarbon added is 1.0% by weight or less based on the gelling agent.