JPH04206460A - Manufacture of button type alkaline battery - Google Patents

Abstract

PURPOSE:To obtain a battery with excellent closed-circuit voltage characteristic by applying sufficient electrolyte absorption on the positive electrode active material surface hydrophilically treated by a surface active agent. CONSTITUTION:A positive electrode active material 1 is filled in a positive electrode case 2, polyethylene dissolved by toluene is coated on the positive electrode active material surface faced to a gasket bottom section and dried, then a nonionic surface active agent is dripped at the center of the positive electrode active material 1. An electrolyte is dripped at the center of the positive electrode active material 1 surface, then a separator material 3 is inserted. When the end section of the positive electrode case 2 is caulked to seal a battery, no electrolyte exists on the positive active material 1 faced to the gasket bottom section, the reduction of the strength of the positive electrode active material 1 faced to the gasket bottom section due to the electrolyte absorption is prevented, and sufficient electrolyte absorption is applied to the positive electrode active material surface hydrophilically treated by the interface active agent. The closed-circuit voltage characteristic is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improved method for manufacturing button-type alkaline batteries.

Conventional Technology Regarding button-type alkaline batteries, a proposal has been made to drop an electrolyte onto a positive electrode active material that has been subjected to hydrophilic treatment in order to retain the electrolyte in the positive electrode active material in order to improve the closed-circuit voltage characteristics.

Problems to be Solved by the Invention However, with this method, in a button-type alkaline battery in which the positive electrode case end is caulked and sealed after the positive electrode and negative electrode are fitted, electrolysis that has seeped onto the positive electrode active material facing the bottom of the gasket can be avoided. The drawback is that the electrolyte may leak when the battery is sealed, or the electrolyte may be absorbed by the entire cathode active material, and the cathode active material may be destroyed by the strength of the cathode active material or the pressure of the seal, resulting in unstable leakage resistance. was there.

The present invention aims to solve these problems and improve the closed circuit voltage characteristics of a button-type alkaline battery.

Means for Solving the Problems In order to solve the above problems, the present invention covers the positive electrode active material facing the bottom of the caskerato with a resin, and then hydrophilizes only the surface of this positive electrode active material with a surfactant. be.

Function: According to the method for manufacturing a button-type alkaline battery of the present invention, when the end of the positive electrode case is caulked to seal the battery, no electrolyte is present on the positive electrode active material facing the bottom of the gasket, and no electrolyte is present on the positive electrode active material facing the bottom of the gasket. The strength of the positive electrode active material facing the bottom of the gasket does not decrease due to absorption, and the surface of the positive electrode active material that has been hydrophilized with a surfactant absorbs the electrolyte sufficiently.

EXAMPLE An example of the present invention will be explained using a silver oxide battery 5R626SW (diameter 6.8 mm, height 2.6 mm) shown in FIG. Melted polyethylene is applied to the surface of the positive electrode active material facing the bottom of the gasket, and after drying, a 7-ion surfactant is dropped into the center of the positive electrode active material. Next, after dropping the electrolytic solution onto the center of the surface of the positive electrode active material, a separator material 3 punched into a separator shape is inserted. Finally, the negative electrode is fitted and the ends of the positive electrode case 2 are caulked to seal the battery.

FIG. 1 is a sectional view of the silver oxide battery 5R626SW manufactured in this manner. In the figure, 1 is a positive electrode active material whose main component is silver oxide, 2 is a positive electrode case, 3 is a separator made of a polyethylene graft film, cellophane, and a liquid-containing material, 4 is a polyethylene coating layer, 5 is a gasket, and 6 is a negative electrode. An intelligent plate 7 which also serves as a terminal is a negative electrode active material whose main component is zinc.

Battery A of the present invention and polyethylene as the positive electrode active material.

We made 50 each of conventional batteries B without coating or hydrophilic treatment, and measured the closed circuit voltage characteristics.
Shown in the table.

Table 1 Measurement Conditions -108C2 and Ω 7.8ms As is clear from Table 1, the battery of the present invention has better closed circuit voltage characteristics than the conventional battery B.

This is because the liquid-retaining property of the surface of the positive electrode active material in the battery A of the present invention is weaker than that in the conventional battery B.

Next, 100 batteries each of the battery A of the present invention and the battery C constructed by subjecting the surface of the polyethylene-coated cathode active material to hydrophilic treatment with a nonionic surfactant were made, and the electrolyte solution from inside the battery immediately after fabrication was prepared. Table 2 shows the results of determining the number of leakages.

Table 2 Note that leakage of the electrolyte was determined by a cresol red color reaction.

As is clear from Table 2, in Battery C, when the end of the positive electrode case is caulked and the battery is sealed, the electrolyte seeps onto the positive electrode active material facing the bottom of the gasket, causing electrolyte leakage. On the other hand, in the battery A of the present invention, the electrolyte is dammed up by the polyethylene coating layer, and no leakage of the electrolyte occurs.

Next, after immersing the positive electrode active material in a nonionic surfactant,
One battery was prepared with a polyethylene coating on the surface of the positive electrode active material facing the bottom of the gasket, and one battery A of the present invention was prepared.
Table 3 shows the results of comparing the leakage resistance characteristics of 00 pieces.

Table 3 n=100 Note) 100 days storage at 45°C at 90% - 5 years storage at normal temperature and humidity When a leaking battery was disassembled, the positive electrode active material facing the bottom of the gasket was destroyed. This is thought to be due to hydrophilic treatment or the electrolyte being applied to the entire positive electrode active material, which caused the electrolyte to seep into the entire positive electrode active material, reducing the strength of the positive electrode active material, making it unable to withstand the pressure when sealing the battery. be done.

On the other hand, in Battery A of the present invention, only the surface of the positive electrode active material other than the portion facing the bottom of the gasket is subjected to hydrophilic treatment, so that it also has excellent leakage resistance.

In the examples of the present invention, only the surface of the positive electrode active material facing the bottom of the gasket was coated with a resin and then subjected to hydrophilic treatment. A similar effect was obtained when the portion was covered with resin.

Furthermore, the resin may be polyethylene, or any resin that is alkali resistant and does not generate gas due to decomposition.

Furthermore, it is preferable to use a nonionic surfactant as the hydrophilic treatment agent or a surfactant having alkali resistance.

Effects of the Invention As described above, according to the method for manufacturing a button-type alkaline battery of the present invention, when the end of the positive electrode case is caulked and the battery is sealed, the electrolyte is deposited onto the positive electrode active material facing the bottom of the gasket. Since it is not present, leakage of the electrolyte will not occur, and damage due to a decrease in the strength of the positive electrode active material facing the bottom of the gasket due to absorption of the electrolyte will not occur.

Moreover, since the surface of the positive electrode active material that has been hydrophilized with a surfactant can sufficiently absorb electrolyte, a battery with excellent closed circuit voltage characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a battery in an embodiment of the present invention. ]...Positive electrode active material, 2...Positive electrode case, 3
... Separator material layer, 4 ... Polyethylene coating layer, 5 ... Gasket, 6 ... Sealing plate,
7...Negative electrode active material.

Claims (1)

[Claims] A method for manufacturing a button-shaped alkaline battery, characterized in that the surface of the positive electrode active material in the portion facing the bottom of the gasket is coated with a resin, and then only the surface of the positive electrode active material is subjected to hydrophilic treatment with a surfactant.