JPH0877987A - Alkaline battery - Google Patents

Abstract

PURPOSE: To prevent the reduction in discharging performance and voltage, the generation of heat, and leakage of liquid even when a gel zinc negative electrode overflows by covering the part from a positive electrode mix surface layer to a gasket abutting part on a metallic case inside face by means of liquid sealant. CONSTITUTION: From a gasket 8 abutting part, which serves as a metallic case sealing part, on a metallic case 6 inside face to the surface layer of a positive electrode mix 1 serving as an opening part, liquid sealant 12 is applied, and a gel zinc negative electrode 2 is filled to be sealed by means of the sealing gasket 8. In this way, the reduction in voltage is prevented even when the gel zinc negative electrode 2 overflows, and consequently, stable quality can be secured even under such a battery using condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive electrode mixture for an alkaline battery, and more particularly to an alkaline battery having a structure in which a gel-like zinc negative electrode active material and a positive electrode mixture molded in a certain shape are separated by a separator When the negative electrode active material overflows from the negative electrode chamber composed of the separator to the positive electrode mixture side during the process or during use of the battery, it is necessary to prevent electrical contact between both active materials, both directly and through the current collector. This prevents the deterioration of discharge performance.

[0002]

2. Description of the Related Art Generally, a battery has a structure in which both positive and negative electrode active materials are separated by an electrically insulating separator. In an alkaline battery, a structure in which a separator is installed in a cup shape inside a cylindrical positive electrode mixture arranged on the outer periphery of the battery, a gel zinc negative electrode is filled in the inside, and the upper surface is closed with a gasket is generally used. If the separation of the two active materials is insufficient, the positive and negative active materials will come into contact with each other, causing an internal short circuit and causing the battery to heat up. There was a risk of damage.

As a countermeasure against this, a method has been devised in which the upper portion of the cup-shaped separator is closed after filling the negative electrode so that the gel zinc negative electrode does not overflow from the upper portion of the cup-shaped separator to the positive electrode mixture side. Further, a skirt portion is provided on the gasket that closes the upper surface of the cup-shaped separator to prevent the gel-like zinc negative electrode from overflowing.

[0004]

However, even when the upper end of the conventional cup-shaped separator is closed or the gasket is provided with a skirt-shaped portion as described above, a strong impact is applied or the battery temperature rises. The swelling of the gelled zinc negative electrode may cause deterioration in discharge performance during use. In addition, these methods prevent simple overflow and the like, and are not effective means for preventing contact between the positive and negative active materials when abnormal overflow occurs. Therefore, it is structurally difficult to completely separate the positive and negative active materials by the conventional method, and there is a risk that the battery performance will be significantly impaired if the battery is not properly handled.

In alkaline batteries, the cause of deterioration of battery performance due to overflow of gelled zinc negative electrode is that current cannot be taken out to an external circuit due to contact between both positive and negative active materials. In order to prevent this, it is desirable that the gelled zinc negative electrode and the positive electrode mixture are structurally completely separated. Generally, such contact of the active material is caused by the impact or temperature being applied to the battery, the gelled zinc negative electrode overflows from the cup-shaped separator, and is mostly caused by dropping on the positive electrode mixture, This problem can be avoided by physically blocking the positive electrode mixture surface layer, which is the open portion of the positive electrode mixture, with an electrical insulator. However, due to the structure of the battery, this electrically insulating material needs to be installed in a small space between the separator and the metal case, and mass production has been difficult when using a separator material or a resin plate.

The present invention solves the above-mentioned problems of the prior art, and the handling and environment of the alkaline battery are inappropriate,
It is an object of the present invention to prevent contact between positive and negative active materials even when the gelled zinc negative electrode overflows to the positive electrode mixture side during use of the battery, thereby preventing deterioration of battery performance.

[0007]

Therefore, in the present invention, by using a liquid sealant as the insulator, the above problem is solved by physically covering the open portion of the positive electrode mixture without impairing mass productivity. It is intended. The sealant applied to the sealing part is generally applied to the metal case as a sealing material between the metal case and the sealing gasket in the alkaline battery, and this is applied from the portion of the metal case where the original sealant is applied to the positive electrode mixture. It is relatively easy to apply the agent to the open portion because of the structure of the battery.

From these findings, by using a liquid sealant as an electric insulator and applying the liquid sealant at least from the sealing part to the positive electrode mixture open part, contact between the positive and negative active materials which becomes a factor of performance deterioration. The present invention was arrived at because it can be physically prevented.

[0009]

The sealant applied to the sealing portion is usually alkali resistant and does not easily come off the coated surface. This sealing agent is usually applied to only the sealing portion with a thin nozzle, but the application range can be easily changed by changing the nozzle. In addition, the sealing part and the open surface of the positive electrode mixture are close to each other in terms of the battery structure, and applying the sealant from the sealing part of the metal case to the open surface of the positive electrode mixture is compared to installing other insulators. And easy. Therefore, by applying the sealing agent as a liquid sealing agent from the sealing portion of the metal case to the open surface of the positive electrode mixture, the gel-like zinc negative electrode of the alkaline battery is improperly filled, which may occur during the battery manufacturing process or during battery use Even if the gelled zinc negative electrode overflows to the positive electrode mixture side, the positive and negative active materials do not come into contact with each other because the liquid sealing agent covers the surface of the positive electrode mixture. Leakage can be prevented.

[0010]

EXAMPLES The present invention will be specifically described below based on Examples and Comparative Examples.

Example The alkaline manganese battery LR6 shown in FIG. 1 was assembled into this example. In FIG. 1, 1 is a positive electrode mixture formed by adding graphite as a conductive material to manganese dioxide, and 2 is a gelling agent and a zinc alloy powder containing no mercury added to an alkaline electrolyte in which potassium hydroxide is dissolved. It is a gelled zinc negative electrode. 3 is a separator, 4 is a negative electrode current collector, 5 is a positive electrode terminal cap, 6 is a metal case, 7 is a battery label exterior, 8 is a sealing gasket, 9 is a bottom plate which forms a negative electrode terminal, and 10 is an insulating washer.

The liquid sealant 12 is applied from the gasket contacting portion on the inner surface of the metal case, which is the sealing portion of the metal case of FIG. 1, to the surface layer of the positive electrode mixture, which is the opening portion, and the gel zinc negative electrode is filled and sealed. A gasket 8 was used to seal the sample.

Sulfonated polyethylene was used as the liquid sealing agent. Comparative Example A sealing agent 11 made of sulfonated polyethylene was applied only to the sealing portion of the metal case of FIG. 1, a gelled zinc negative electrode was filled, and a sealing gasket was used for sealing to make a comparative example.

In this way, 1000 batteries each of the present example and the comparative example were filled with the gelled zinc negative electrode, and the voltage drop due to the overflow of the gelled zinc negative electrode when the battery was impacted was investigated. Are shown in (Table 1).

[0015]

[Table 1]

From the results shown in (Table 1), in the example of the present invention, no voltage drop was observed even when the gelled zinc negative electrode overflowed, and stable quality could be ensured even under such battery usage conditions. It was Further, in the battery in which the voltage drop was observed in the comparative example, the gelled zinc negative electrode overflowed on the positive electrode mixture and was accompanied by heat generation.

Although sulfonation-type polyethylene was used for both the liquid sealing agent and the sealing agent in this example and the comparative example, the same effect can be obtained for the pitch-based and butadiene-based materials which have electric insulation and are alkali resistant. showed that.

[0018]

As described in detail above, according to the present invention, even if the gelled zinc negative electrode overflows from the cup-shaped separator during the production process and use of the alkaline battery, the discharge performance, the voltage drop, the heat generation, and the leakage of the liquid may occur. And can provide good quality alkaline batteries.

[Brief description of drawings]

FIG. 1 is a half sectional view of an alkaline battery LR6 used in the present invention.

[Explanation of symbols]

 1 Positive Electrode Mixture 2 Gel Zinc Negative Electrode 3 Separator 4 Negative Electrode Current Collector 5 Positive Electrode Terminal Cap 6 Metal Case 7 Label Exterior 8 Gasket 9 Bottom Plate 10 Insulating Washer 11 Sealant 12 Liquid Sealant

Claims (1)

[Claims] 1. An alkaline battery in which a gelled zinc negative electrode made of zinc alloy powder is set as a negative electrode active material at the center of the battery, and a positive electrode mixture is provided on the outer periphery of the negative electrode via a separator. That is, the open part of the positive electrode mixture, that is, the part from the positive electrode mixture surface layer to the gasket contacting part on the inner surface of the metal case is electrically insulated and covered with an alkali-resistant liquid sealant. Alkaline battery.