JPH0517808Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field of application> This invention relates to dry batteries, and more specifically, improves leakage resistance by improving the physical properties of the top cover paper and the mounting structure on the top surface of the positive electrode mixture. Regarding.

<Prior art> As shown in Fig. 2, a zinc can 1 obtained by molding zinc pellets into a can shape by impact extrusion is used as a negative electrode, and manganese dioxide as a main component is placed inside this zinc can. A dry battery is constructed by storing a positive electrode mixture 2 which is made by kneading powder with an electrolyte and forming it under pressure, and press-fitting a carbon rod 4 as a current collector into the positive electrode mixture. This is a paper-lined method in which the periphery is wrapped in a so-called paper separator 11 made by coating and impregnating kraft paper or Kent paper with an electrolyte in advance, and zinc chloride-based separators using an electrolyte whose main component is zinc chloride are widely used. There is.

In the case of such a paper-line type dry battery, the sealing structure at the opening of the zinc can is a central hole on the top surface of the positive electrode mixture that has approximately the same diameter as the inside diameter of the zinc can and in the center that has approximately the same diameter as the outside diameter of the carbon rod. After placing the top cover paper 13 having the following properties, a synthetic resin sealing gasket 5 having a carbon rod insertion hole in the center is fitted into the opening of the zinc can, and a tight gasket is placed around the opening of the zinc can or around the carbon rod. A method is adopted in which a sealant 10 such as wax is interposed.

<Problems to be solved by the invention> By the way, the top cover paper 1 used in the above-mentioned sealing structure
3, those that have been treated with water repellency by impregnating them with a water repellent such as Teflon are generally used. For zinc-based batteries, the electrolyte in the positive electrode mixture may overflow from the positive electrode mixture 2 through the paper separator 11, etc. that is in close contact with the inner circumferential surface of the zinc can, due to concentration polarization as the dry battery discharge progresses. There is a problem in that liquid gradually accumulates on the top surface of the cover paper and eventually causes external leakage.

<Means for solving the problem> The dry cell of this invention is constructed by storing a positive electrode mixture with a current collector press-fitted in the center in a zinc can, and placing a cover paper on top of the positive electrode mixture. In a dry battery, the gist is to eliminate the water repellency of the top cover paper and to separate the end surface of the top cover paper on the stage collector side from the outer circumferential surface of the current collector.

<Function> By using the above means, the electrolyte that overflows through the paper separator etc. quickly moves to the positive electrode mixture side through the top cover paper or between the top cover paper and the current collector. It will no longer accumulate on the top.

<Example> In FIG. 1, a positive electrode mixture 2 is stored in a zinc can 1 with a paper separator 11 interposed therebetween.
A carbon rod 4 is press-fitted into the positive electrode mixture, and a top cover paper 3 is placed on the top surface of the positive electrode mixture. A synthetic resin sealing gasket 5 having a carbon rod insertion hole is attached to the opening of the zinc can 1 . The upper end of the carbon rod 4, which protrudes slightly from the upper surface of the sealing gasket through this insertion hole, is pressed against the lower surface of the positive terminal of a metal positive terminal plate 6 placed on the upper surface of the sealing gasket.
A heat-shrinkable tube is wound around the outer periphery of the zinc can 1, the upper end of which is held between the sealing gasket 5 and the positive terminal plate 6. Further, an insulating ring 8 made of synthetic resin is placed on the peripheral edge of the upper surface of the positive electrode terminal plate 6, and the curled edge of the metal jacket 9 presses against the upper surface of the insulating ring 8. A sealant 10 is filled between the recess formed around the insertion hole of the gasket 5, the outer peripheral surface of the carbon rod, and the lower surface of the positive terminal plate.

The outer diameter of the top cover paper 3 is approximately equal to the inner diameter of the zinc can,
Further, a central hole 3a having a diameter larger than the outer diameter of the carbon rod is formed in the center thereof. As a result, the outer peripheral end of the top cover paper is in pressure contact with the paper separator 11, and the inner end surface (the peripheral wall surface of the central hole 3a) and the outer peripheral surface of the carbon rod 4 are separated from each other.

<Effects of the invention> According to the dry cell of this invention constructed as described above, the electrolyte in the positive electrode mixture that overflows through the separator etc. as discharge progresses will no longer accumulate on the upper surface of the top cover paper. This not only improves the leakage resistance of the battery, but also allows the overflowing electrolyte to be removed by passing it between the top cover paper and the current collector, so that the electrolyte is absorbed by the electrolyte due to concentration polarization as the discharge progresses. The positive electrode mixture, whose concentration is decreasing, can be moved to the current collector side, increasing the utilization rate of the positive electrode mixture.
Battery discharge performance can be improved. Furthermore, since the process of imparting water repellency to the top cover paper and the need for materials such as water repellent agents are unnecessary, there is also the advantage that this leads to a corresponding reduction in the cost of the battery.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing an embodiment, and FIG. 2 is a partial sectional view showing a conventional example. 1...Zinc can, 2...Positive electrode mixture, 3,13...
Top cover paper, 4... carbon rod, 11... paper separator,
3a...Central hole.

Claims (1)

[Scope of utility model registration request] In a dry battery constructed by storing a positive electrode mixture with a current collector press-fitted in the center in a zinc can and placing a top cover paper on top of the positive electrode mixture, the water repellency of the top cover paper is eliminated and the top cover paper collects current. A dry cell characterized in that a body side end surface and an outer circumferential surface of a current collector are separated from each other.