JPH0517806Y2 - - Google Patents

Description

[Detailed explanation of the invention] <Industrial application field> This invention relates to dry batteries. Specifically, the content of chemical manganese dioxide and natural manganese dioxide in the positive electrode mixture is changed between the outside and inside of the positive electrode mixture. This invention relates to a dry battery that can reduce costs without deteriorating discharge performance.

<Prior art> In a dry battery that uses manganese dioxide as a positive electrode active material and zinc as a negative electrode active material, and uses a mixture of zinc chloride and ammonium chloride or an electrolyte mainly composed of zinc chloride, a zinc can is placed inside the negative electrode zinc can. A paper separator adhered to the inner surface and impregnated with the electrolytic solution, a positive electrode mixture made of manganese dioxide as a main component and pressure-molded into a cylindrical shape, and a carbon rod serving as a positive electrode current collector are each coaxially loaded. It's on. The manganese dioxide used in such dry batteries includes natural manganese dioxide obtained from naturally occurring manganese dioxide ore, chemical manganese dioxide obtained by chemically processing natural manganese dioxide, and rhodochrosite, which is obtained by chemically processing and electrolytically processing. There are electrolytic manganese dioxide etc. that can be obtained. By the way, manganese dioxide for dry batteries is not only chemically highly pure, but also has a γ-type X-ray crystal structure and high water content, which exhibits particularly high performance and is suitable for high loads, continuous discharge, etc. has been done. For this reason, with the miniaturization and high performance of various electrical devices, high-output power sources are now required, and the content of manganese dioxide, which is in the γ form and has high water content, is particularly high, and therefore has a high activity level. The amount of electrolytic manganese dioxide added to the positive electrode mixture has become considerably large.

<Problems to be solved by the invention> However, although electrolytic manganese dioxide exhibits excellent performance as a positive electrode active material, its production requires a great deal of effort and process, so natural manganese dioxide and chemical manganese dioxide are They have the disadvantage that they are considerably more expensive than other batteries, which is an obstacle to efforts to reduce the cost of dry cell batteries.

For this reason, it may be possible to reduce costs by increasing the content of natural manganese dioxide, which has a very large cost advantage, in the positive electrode mix, but natural manganese dioxide has a high utilization rate in light load discharges and is one of the Although its performance in discharge is almost on par with electrolytic manganese dioxide, its utilization rate in high-load discharge is significantly inferior, so the amount added must currently be limited from the standpoint of improving the discharge characteristics of dry batteries.

<Means for solving the problem> The dry battery of this invention has a current collector in the center and a positive electrode mixture containing manganese dioxide as an active material is loaded into a zinc can. The mixture consists of at least two annular layers, an inner annular layer and an outer annular layer, in the radial direction of the cross section of the zinc can, the active material of the outer annular layer is mainly chemical manganese dioxide, and the active material of the inner annular layer is natural manganese dioxide. The main purpose of this study is to focus on:

That is, when the positive electrode mixture consists of two annular layers, the outer annular layer has a composition mainly composed of chemical manganese dioxide, and the inner annular layer has a composition mainly composed of natural manganese dioxide, as described above. In addition, when the positive electrode mixture has three or more annular layers, for example,
The content of chemical manganese dioxide in the outermost annular layer is approximately 100%, the content of natural manganese dioxide in the innermost annular layer is approximately 100%, and the content of natural manganese dioxide in the other annular layers increases as the inner side of the battery increases. In addition, the outer side of the battery has a higher content of chemical manganese dioxide. Furthermore, the utilization rate of chemical manganese dioxide during high-load discharge is considerably higher than that of natural manganese dioxide, so simply increasing the content of chemical manganese dioxide in the outer layer of the positive electrode mixture as described above will improve the high-load discharge characteristics. is quite good, but in order to further improve the characteristics,
It goes without saying that a structure in which a small amount of electrolytic manganese dioxide is added to the outer layer of the positive electrode mixture may also be used.

<Operation> Generally, when a dry battery is discharged, the discharge reaction in the positive electrode mixture proceeds from the outer periphery of the mixture (zinc can side) toward the inside of the mixture. Therefore, in the case of high-load discharge, the manganese dioxide in the outer periphery of the mixture mainly participates in the battery discharge reaction, and in the case of light-load discharge, the manganese dioxide in the entire mixture participates in the discharge reaction. In particular, it is known that during high-load continuous discharge, manganese dioxide in the mixture near the carbon rod hardly participates in the discharge reaction. Therefore, as mentioned above, a mixture mainly composed of chemical manganese dioxide with relatively high activity is arranged on the outer circumferential side of the positive electrode mixture, and a mixture mainly composed of natural manganese dioxide is arranged on the inner circumferential side. With this structure, during high-load discharge, the discharge reaction of the chemical manganese dioxide on the outer periphery of the positive electrode mixture results in a high discharge, and during light-load discharge, the discharge reaction between natural manganese dioxide and chemical manganese dioxide in the entire mixture results in high discharge. Performance can be obtained. Furthermore, since the inner part of the mixture is mainly composed of natural manganese dioxide, which has a very large cost advantage, the cost of the positive electrode mixture is reduced accordingly, and the cost of the battery can be reduced.

<Example> In FIGS. 1A and 1B showing an example in which the present invention is applied to a single-type dry battery, a carbon rod 3 is press-fitted into the center of a zinc can 1 through a paper pallet 2 and a bottom paper 2a. The positive electrode mixture 3 is accommodated and loaded. A top cover paper 5 is placed on the top surface of the positive electrode mixture 2, and from the top surface of the sealing gasket 6 that seals the opening of the zinc can, there is a gap between the carbon rod and the carbon rod insertion hole of the sealing gasket 6, and a gap between the carbon rod and the carbon rod insertion hole of the sealing gasket 6. A sealing agent 11 is applied and filled up to the portion of the insertion hole facing the upper cover paper. Further, a heat-shrinkable tube 7 is wound and tightly attached between the outer periphery of the zinc can and the upper surface of the sealing gasket. On the upper surface of the sealing gasket of the heat-shrinkable tube 7 is a positive terminal plate 8 whose central positive terminal portion is in contact with the carbon rod 3.
Further, negative electrode terminal plates 9 are in contact with the bottom surfaces of the zinc cans 1, respectively, and are pressed against the contact surfaces by the outer cans 10.

The positive electrode mixture 4 is composed of an outer annular layer 4a located on the inner peripheral surface side of the zinc can and an inner annular layer 4b located on the outer peripheral surface side of the carbon rod. outer annular layer 4
The inner annular layer a contains manganese dioxide mainly composed of chemical manganese dioxide, and the inner annular layer 4b contains manganese dioxide mainly composed of natural manganese dioxide as an active material.

<Effect of the invention> This invention is as explained above for dry batteries, and when the battery is discharged under high load, due to the discharge reaction of chemical manganese dioxide present in large amounts around the outer periphery of the positive electrode mixture,
Furthermore, during light load discharge of the battery, high discharge performance can be obtained due to the discharge reaction between natural manganese dioxide and chemical manganese dioxide in the entire positive electrode mixture. Therefore, it is possible to use a large amount of natural manganese dioxide, which has a great cost advantage, without causing a decrease in the difference in discharge performance, which has the effect of significantly reducing the cost of dry batteries, and making it possible to use it industrially. The value is high.

[Brief explanation of the drawing]

FIG. 1A is a partial sectional view showing an embodiment of the present invention, and FIG. 1B is a sectional view taken along the line -- in FIG. 1A. 1... Zinc can, 2... Paper separator, 3... Carbon rod, 4... Positive electrode mixture, 4a... Outer annular layer, 4
b...Inner annular layer.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. In a dry battery in which a positive electrode mixture containing a current collector in the center and containing manganese dioxide as an active material is loaded into a zinc can, the positive electrode mixture has a cross-sectional radius of the zinc can. It consists of at least two annular layers, an inner annular layer and an outer annular layer in the direction, and the active material of the outer annular layer is mainly composed of chemical manganese dioxide,
A dry battery characterized in that the active material of the inner annular layer is mainly natural manganese dioxide. 2. Utility model registration claim 1, characterized in that the annular layer has a higher content of natural manganese dioxide as it goes inside the battery, and a higher content of chemical manganese dioxide as it goes outside the battery. dry battery.