JPS63254672A - Cylindrical manganese dry cell - Google Patents

Abstract

PURPOSE:To improve the resistance against the liquid leakage caused by the over-discharge by inserting an insulating layer only between the bottom face of a bottom paper cup except the rising peripheral portion and the inner bottom face of a negative electrode zinc can. CONSTITUTION:A plastic plate 6 with nearly the same size as the inner diameter size of a can 5 is put on the bottom face of the bottomed cylindrical negative electrode zinc can 5 as an insulating layer. A positive electrode black mix mainly made of manganese dioxide is cylindrically molded, with a carbon bar 2 penetrating at the center, they are enveloped by a bottom paper cup 3 (not coated with the insulating paper) and an electrolyte separator 4 and stored in the can 5. The cell reaction is suppressed to some degree by the cup 3 alone at the rising peripheral portion of the cup 3 according to this constitution, the reaction is almost completely suppressed by the cup 3 and plate 6 on the bottom face. The local concentration of the reaction is thereby reduced, the liquid leakage caused by the over-discharge can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to general cylindrical manganese dry batteries such as single type or AA type, and particularly relates to technology for preventing leakage due to overdischarge. .

(Prior Art) FIG. 2 shows the basic structure of a typical cylindrical manganese dry battery before it is sealed. As is well known, recent cylindrical manganese dry batteries of this type are manufactured using a paper line method.

A positive electrode mixture 1 containing manganese dioxide as a main component is formed into a cylindrical shape through a carbon rod 2 in the center, and its bottom is covered with a bottom cup 3 having a certain depth, and its circumferential surface is made of kraft paper. It is covered with a separator 4 containing an electrolyte.

The positive electrode mixture 1 wrapped in the electrolyte separator 4 and the bottom cup 3 is tightly housed in the bottomed cylindrical negative electrode zinc can 5. After that, the upper end opening of the negative electrode zinc can 5 is sealed, and the external terminal and exterior are attached.
A typical dry battery is completed.

The battery reaction between the positive electrode and the negative electrode is carried out through the separator 4 obtained by moving ions and reaction-contributing substances between the two electrodes, and the battery reaction hardly progresses in the area where the bottom cup 3 is interposed. In order to completely prevent a battery reaction in the area where the bottom cup 3 is located, in many cases, one side of the bottom cup 3 is coated with insulating paper 3a having high electrical insulation properties.

(Problems to be Solved by the Invention) The negative electrode zinc can 5 serves not only as an electrode but also as a case for sealing the power generation element. Due to discharge negative electrode zinc can 5
If too much is consumed locally, a hole will form in the negative electrode zinc can 5, and leakage will begin from there.

This is overdischarge leakage.

In the conventional battery having the structure shown in FIG.
This is caused by a hole in the zinc can 5 at the section (Fig. 2). This means that a particularly intense reaction occurs near the boundary between the part of the bottom cup 3 coated with insulating paper 3a that prohibits the battery reaction from occurring and the part where the battery reaction occurs through the separator 5. This means that the zinc can 5 is consumed quickly. However, it is not clear why this phenomenon occurs.

This invention was made in view of the above-mentioned conventional problems, and its purpose is to improve resistance to over-discharge leakage caused by holes near the outer periphery of the bottom cup 3.

(Means for Solving the Problem) Therefore, in this invention, instead of coating one surface of the bottom cup 3 with insulating paper over the entire surface, the bottom surface of the bottom cup except for the rising peripheral surface part and the negative electrode The structure is such that an insulating layer is interposed only between the zinc can and the inner bottom surface.

(Function) The bottom cup alone has some degree of insulation (it does not contain a large amount of electrolyte like a separator), and this alone suppresses battery reactions to some extent. The insulating layer is not present on the raised peripheral surface of the bottom cup, but only on the bottom surface. Therefore, in the bottom portion, the battery reaction is almost completely suppressed by the two layers of the bottom cup and the insulating layer, and in the rising circumferential portion of the bottom cup, the battery reaction is suppressed by this alone. Therefore, the boundary between the battery reaction permissible band and the battery reaction prohibited band does not appear as sharply as in the conventional case.

Further, the outer peripheral edge of the insulating layer interposed only between the bottom surface of the bottom cup and the inner bottom surface of the negative electrode zinc can is located at the corner of the bottom surface and the peripheral surface of the negative electrode zinc can. This corner of the negative electrode zinc can is thicker than the rounded part due to the method of forming it into a bottomed cylindrical shape. Therefore, even if this portion is consumed faster than other portions, the time required for perforation will not be particularly faster than other portions.

(Example) FIG. 1 shows the basic structure of a manganese dry battery before sealing according to an example of the present invention. A positive electrode mixture 1 containing manganese dioxide as a main component is formed into a cylindrical shape with a carbon rod 2 passed through its center, and the bottom of the positive electrode mixture 1 is formed into a bottom cup 3 with some depth (conventionally, an insulating paper 3a is used). (not coated), and its peripheral surface is covered with an electrolyte separator 4.

Inside the negative electrode zinc can 5 formed into a cylindrical shape with a bottom, the above-mentioned plastic plate 6 as an insulating layer is first set so as to be in contact with the bottom surface. The outer diameter of the plastic plate 6 is approximately equal to the inner diameter of the zinc can 5, and the outer peripheral edge of the plastic plate 6 is located at the corner of the bottom and circumferential surface of the zinc can 5.

A positive electrode mixture 1 encapsulated by a bottom cup 3 and an electrolyte separator 4 is tightly housed in a negative electrode zinc can 5 with a plastic plate 6 set at the inner bottom. Thereafter, the upper end opening of the negative electrode zinc can 5 is sealed, and an external terminal and exterior packaging are applied.

In the above configuration, in the portion where the rising circumferential surface portion of the bottom cup 3 is present, the battery reaction is suppressed to some extent by the bottom cup 3 alone. Furthermore, on the bottom surface, the battery reaction is almost completely suppressed by the bottom cup 3 and the plastic plate 6. As a result, the boundary between the zone that allows battery reactions and the zone that suppresses battery reactions becomes two stages and becomes unclear. Therefore, the local concentration of reaction near the outer periphery of the plastic plate 6 is less severe than in the past. In addition, the outer peripheral edge of the plastic plate 6 is thicker than other parts of the negative electrode zinc can 5.
Since the battery is located at the corner of the battery, even if the consumption rate is slightly higher than other parts, holes will not occur frequently in this part due to overdischarge.

In addition, in the above embodiment, the plastic plate 6 is used as the insulating layer.
However, the present invention is not limited thereto, and the bottom cup 3
Other methods may be used, such as coating only the bottom part of the insulating paper with insulating paper.

(Effects of the Invention) As explained in detail above, in the cylindrical manganese battery according to the present invention, violent reaction concentration does not occur near the boundary between the bottom cup that covers the positive electrode mixture and the separator as in the conventional case. At the same time, since mild reaction concentration occurs at the thick corners of the negative electrode zinc can, the frequency of overdischarge leakage caused by holes in these corners is significantly lower than in the past.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the basic structure of a cylindrical manganese dry battery according to an embodiment of the present invention before sealing, and FIG. 2 is a sectional view showing the basic structure of a conventional cylindrical manganese dry battery before sealing. 1... Positive electrode mixture 2... Carbon rod 3... Bottom cup 4... Separator 5... Negative electrode zinc can 6... Plastic plate (insulating layer) Figure 1

Claims (1)

[Claims] (1) A positive electrode mixture formed into a cylindrical shape, the bottom of which is covered with a bottom cup with a certain depth, and the circumferential surface of which is covered with an electrolyte separator, is placed in a bottomed cylindrical negative electrode zinc can. A cylindrical manganese dry battery structured to be housed in a cylindrical manganese dry battery, characterized in that an insulating layer is interposed between the bottom surface of the bottom cup excluding the rising peripheral surface portion and the inner bottom surface of the negative electrode zinc can. Dry battery.