JPH0518225B2 - - Google Patents

Description

[Detailed description of the invention]

<<Industrial Application Field>> The present invention relates to an improvement in a cylindrical alkaline battery having a structure in which a metal current collector rod is inserted into a gelled zinc negative electrode. <<Conventional technology>> The basic structure of cylindrical alkaline manganese batteries such as LRO3 type and LR6 type is that a positive electrode mixture, a separator, and a gelled zinc negative electrode are coaxially loaded into a bottomed cylindrical positive electrode can. , the opening of the positive electrode can is sealed with a sealing gasket and a negative terminal plate, and the upper end of the metal current collector rod inserted into the center of the gelled zinc negative electrode passes through the center of the sealing gasket and contacts the inner surface of the negative terminal plate. The structure is joined by spot welding. Brass is generally used as the metal current collector rod. A very thin brass rod is used as the current collector rod in order to maximize the filling capacity of the negative electrode and to reduce the cost of the brass material.
For example, the LR6 type battery uses a brass rod with a diameter of about 1.5 mm. In order to ensure that the gelled zinc negative electrode is consumed uniformly, it is desirable to immerse the metal current collector rod as deep as possible (downward) into the negative electrode. For this reason, the longer the current collector rod is, the better, but it is extremely difficult to produce long, thin metal rods with good yield. For example, if you want to make a brass rod with a diameter of 1.5 mm with high dimensional accuracy without bending or scratches, the maximum length is about 35 mm. For this reason, in conventional cylindrical alkaline batteries, the length of the current collector rod is relatively short, and the current collector rod is usually immersed only to about half the depth of the negative electrode. ≪Problems to be solved by the invention≫ If the current collector rod is thin and the length of immersion into the negative electrode is short, its current collection performance will naturally not be high, and it will be difficult to discharge into the deep part of the negative electrode that the current collector rod cannot reach. is more likely to occur. However, in the past, it can be said that this decrease in battery performance was compensated for by increasing the degree of amalgamation of the zinc negative electrode (by increasing the amount of mercury to 10% or more). As is well known, reducing the mercury content of batteries as much as possible has become a major technical challenge in recent years from the perspective of environmental pollution. When the mercury content (degree of amalgamation) in the negative electrode of an alkaline battery is reduced, the performance deterioration due to the use of the thin and short current collector rod mentioned above becomes apparent. This invention has been made in view of the above-mentioned conventional problems, and its purpose is to construct a substantially long current collector rod using a short metal rod that is not particularly difficult to manufacture, and to reduce the degree of amalgamation of the zinc negative electrode. The objective is to realize a cylindrical alkaline battery whose performance does not deteriorate even when the battery is lowered. <Means for Solving the Problems> In this invention, two short metal rods are connected to form one long current collector rod, and the connecting portion of the two metal rods is immersed in a gelled zinc negative electrode. It is characterized by what it did. <<Operation>> In this invention, a long current collector rod consisting of two metal rods connected together is deeply immersed in a gelled zinc negative electrode to promote a uniform discharge reaction of the negative electrode, and
Its current collection performance is also improved. <<Example>> FIG. 1 shows the overall structure of a cylindrical alkaline battery according to an example of the present invention. A positive electrode mixture 12 made of manganese dioxide and preformed into a cylindrical shape is loaded into a bottomed cylindrical positive electrode can 10 made of metal. A cylindrical separator 14 impregnated with an alkaline electrolyte is placed in close contact with the inner cylindrical portion of the positive electrode mixture 12, and the inside of the separator 14 is further filled with a gelled zinc negative electrode 16. Zinc in the negative electrode 16 is mercury amalgamated, but its mercury content is as low as 4% or less. A combination of a plastic sealing gasket 18 and a metal negative terminal plate 20 is fitted into the opening of the positive electrode can 10 . By curling the opening edge portion of the positive electrode can 10 inward, the sealing gasket 18 is compressed and the battery case is sealed. The metal current collector rod 22 is inserted into the center of the gelled zinc negative electrode 16 . The upper end of the current collector rod 22 passes through a hole in the central boss portion of the sealing gasket 18, and its end surface is spot welded to the center of the inner surface of the negative electrode terminal plate 20. The current collecting rod 22 includes a first metal rod 24 and a second metal rod 26
It is made by joining two pieces together, and brass is used as the metal material. Details of this current collecting rod 22 are shown in FIG. As shown in FIG. 2, a small flange 24a is formed at the upper end of the first metal rod 24, and a fitting protrusion 24b is formed coaxially at the lower end. A fitting hole 26a is formed in the upper end surface of the second metal rod 26, into which the fitting protrusion 24b of the first metal rod 24 is press-fitted. The assembly process related to the above-mentioned current collecting rod 22 will be explained. First, the first metal rod 24 is attached to the inner surface of the negative terminal plate 20.
The flanges 24a are joined by spot welding. Next, the first metal rod 24 is inserted into the hole in the boss portion of the sealing gasket 18, and the negative electrode terminal plate 20 and the sealing gasket 18 are assembled. Next, a second metal rod 2 is attached to the lower end of the first metal rod 24 that penetrates from the sealing gasket 18.
Connect 6. That is, the fitting protrusion 24b of the first metal rod 24 is press-fitted into the fitting hole 26a of the second metal rod 26. Both metal rods 24 and 26 are now mechanically and electrically coupled. This is inserted into the center of the gelled zinc negative electrode 16. Then, the connecting portion between the first metal rod 24 and the second metal rod 26 is immersed into the negative electrode 16. Therefore, this connection part does not come into contact with air, so that the electrical contact of the connection part does not deteriorate due to oxidation or the like. Since the two metal rods 24 and 26 are connected together to form one long current collector rod 22, even if it is not possible to make each metal rod thin and long due to manufacturing problems, it is possible to The rod is long and thin, and has a sufficiently effective current collecting effect even deep within the gelled zinc negative electrode. Furthermore, since the current collector rod is thin, the amount of filling of the negative electrode 16 is not reduced. In addition, since the current collecting effect is good, the negative electrode 16
Even when the degree of amalgamation was set to 4% or less, high discharge performance could be maintained. The effect of the present invention was confirmed through the following comparative test. Regarding LR6 type alkaline manganese batteries, a conventional battery with a current collector rod length of 20 mm and a battery of the present invention using a 45 mm current collector rod made by connecting two metal rods (the thickness of the current collector rods are both different). 1.5 mm), the degree of amalgamation of the zinc negative electrode is 2%, 3%, 4
% and 5%, and the discharge time of each was compared. The test conditions were continuous discharge with a 75Ω load, a final voltage of 0.9V, and a test temperature of 20°C, and the minimum and maximum values are shown for each of the five batteries.

[Table] As is clear from the test results, it is clear that the present invention can provide good discharge performance even in batteries with a low degree of amalgamation in the negative electrode, both in terms of initial performance and performance after 20 days of storage. It became. Note that the material of the metal rod is not limited to brass, and copper, galvanized iron, or the like may be used. Further, the fitting structure shown in the embodiment allows for good assembly efficiency when connecting two metal rods, but the present invention is not limited thereto, and the two metal rods may be joined by welding or the like. <<Effects of the Invention>> As explained in detail above, according to the present invention, the substantially thin and long current collecting rod is composed of two short metal rods that are easy to manufacture, so that high current collecting performance can be obtained from the negative electrode. This can be achieved without reducing the amount of filling, and therefore good discharge performance can be obtained even if the degree of amalgamation of the negative electrode is lowered.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an alkaline battery according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the current collector rod in FIG. 1. 10... Positive electrode can, 12... Positive electrode mixture, 14...
Separator, 16... negative electrode, 18... sealing gasket, 20... negative electrode terminal plate, 22... metal current collector rod, 24... first metal rod, 26... second metal rod,
24b...fitting protrusion, 26a...fitting hole.

Claims (1)

[Scope of Claims] 1 A positive electrode mixture, a separator, and a gelled zinc negative electrode are coaxially loaded in a bottomed cylindrical positive electrode can, and the opening of the positive electrode can is connected to a sealing gasket and a negative electrode terminal plate. A cylindrical alkali metal current collector rod that is sealed and whose upper end passes through the center of the sealing gasket and is electrically connected to the inner surface of the negative electrode terminal plate is inserted into the center of the gelled zinc negative electrode. The battery is characterized in that the metal current collector rod is made up of two metal rods connected together, and the connecting portion of the two metal rods is immersed in the gelled zinc negative electrode. Cylindrical alkaline battery. 2. The cylindrical alkaline battery according to claim 1, wherein the ends of the two metal rods are connected by a fitting structure. 3. The cylindrical alkaline battery according to claim 1, wherein the zinc of the negative electrode is amalgamated with 4% or less of mercury.