JPS6178055A - Cylindrical alkaline battery - Google Patents

Abstract

PURPOSE:To prevent crack etc. by reducing spring back of positive pole mixture in forming by forming outer peripheral face of positive pole mixture to be tapered by a metal mold and contacting to the inner face of a positive pole can by re-pressurization after inserting in the positive pole can. CONSTITUTION:Positive pole mixture 1 is made by containing graphite of 3-8wt% in manganese dioxide and formed by a metal mold to be a taper whose upper diameter is almost the same as the internal diameter of a positive can 2 and whose lower diameter is smaller than the upper diameter. And it is injected in the positive pole can 2 whose inner face is coated by a conductive film and re-pressurized to be contacted to the inner face of the can 2, and combined with a separator 4 and a negative pole 5 gelatinizing powder zinc with electrolyte to form a cylindrical alkaline battery. Then, spring back of the positive pole mixture 1 is reduced to prevent crack and forming pressure is increased to increase content of positive pole active matter, and battery performance and productivity can be improved.

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention is characterized by molding a positive electrode mixture into a specific shape.
This invention relates to a cylindrical alkaline battery in which the active material of the positive electrode is increased in strength, thereby improving its core performance.

<Prior art> Alkaline electrolytes that use alkaline electrolytes or powdered zinc gelled by C-IC as negative electrodes have a significantly increased surface area of the negative electrode zinc compared to manganese dry batteries that use zinc cans, and their discharge performance has improved. Since the performance is significantly improved, there is a great demand for it as a battery for high-load, large-current extraction. Behind such an alkaline battery, what is called a cylindrical alkaline battery is that a positive electrode active material such as manganese dioxide is mixed with graphite or an appropriate binder. Afterwards, the positive electrode mixture formed into a hollow cylindrical shape using a mold, an upper punch, a lower punch, etc. is placed on the outside of the above-mentioned fi IU through a cylindrical separator. The so-called inside-out type, which is housed inside a can, is common.

<Problems to be Solved by the Invention> However, the cylindrical alkaline battery having the above configuration has the following problems. That is, the hollow cylindrical positive electrode mixture is
Usually, the upper and lower outer diameters are molded to be approximately the same. Although this can be said to be suitable for ensuring uniform contact with the inner surface of the positive electrode can when housed in the positive electrode can, when increasing the positive electrode mixture and increasing the molding pressure by 8, the mold In particular, small cylindrical molds such as LR6゜03.1 may cause damage to the mold, etc., or cracks or chipping of the mixture due to increased springback during removal from the LR6゜03.1. This is a major obstacle in increasing the discharge capacity of alkaline batteries by increasing the density of the positive electrode mixture 1a.

Furthermore, since the outer diameters of the upper and lower parts are approximately the same, the positive electrode mixture is placed in the correct position from the mold to the center (J), resulting in the outer surface and the inner circumferential surface of the mold being in constant pressure contact with each other. For example, in an alkaline manganese battery, when trying to increase the manganese dioxide content by lowering the graphite content in the positive mixture ~1, the If of the positive electrode mixture and the molding die should be adjusted by the amount of graphite content reduction. Since t?M increases, it also increases the occurrence of mold breakage and cracking of the mixture as described above.For this reason, in current cylindrical alkaline manganese batteries, graphite Ratio (ratio of manganese dioxide and graphite to total 0) from 10 to
It is the fQ condition that must be set quite high, about 15ffiffi%.

<Means for solving the problem> The cylindrical alkaline battery of the present invention has an outer diameter on the mold extraction side that is approximately the same as the inner diameter of the positive electrode can, and an outer diameter on the opposite side that is smaller than the inner diameter of the positive electrode can. The gist of this method is to insert a positive electrode mixture whose outer surface is tapered by grinding it into a positive electrode can and pressurize it again, thereby bringing it into close contact with the inner surface of the can.

In addition to this configuration, an appropriate conductive film may be applied to the inner surface of the positive electrode can.

By making the outer circumferential surface of the positive electrode mixture tapered as described above, springback during removal from the mold can be significantly reduced, and the positive electrode mixture molding pressure can be increased to increase the positive electrode active material content. be able to. Similarly, since the ratio of [φ1] between the positive electrode mixture and the mold at the time of removal from the mold is reduced, the ratio of graphite can be made considerably lower than before, and the content a of the positive electrode active material can be further increased. Further, by applying a conductive film to the inner surface of the positive electrode can, the positive electrode mixture and the positive electrode can can be brought into reliable contact even if the re-pressing force of the positive electrode mixture after inserting the positive electrode is small.

<Example> First, the case where the positive electrode mixture 21 is taken out from gold Ill by referring to FIGS. 2 to 2C will be explained.

? I! Figure 2 shows the completion of molding of the positive electrode mixture 21, so 10 is a mold, 11 is an upper punch, 12 is a top and bottom punch, and 13 is a hint turbine. The circumferential portion 10a has a tapered shape that gradually expands in diameter upward, so that the positive electrode mixture 21 has an outer diameter on the extraction side as shown in FIG. It is molded to be larger than the outer diameter t2 of the opposite ff111. The outer diameter t1 of the mold removal side is made approximately the same as the inner diameter of the portion of the iE electrode can that accommodates one mixture. From the state shown in FIG. 2, the upper bunch 11 is moved upward to release the pressure applied to the positive electrode mixture 21 from above, resulting in the state shown in FIG. 8, and then the lower bunch 12 is similarly moved upward. At this time, the positive* mixture 21 pushed up by the lower punch 12 moves upward on the tapered inner peripheral part 10a of the mold 1o.
The gap between the outer surface of the mixture 21 and the inner peripheral portion 10a gradually increases. Therefore, the springback of the positive electrode mixture 21 is gradually suppressed, and the difference between the positive electrode mixture 21 and gold t10 is 1? (Since it becomes lower as it is shot, the positive electrode mixture 21 can be taken out smoothly as shown in FIG. 2C.

A positive* molded into a dauber shape using the same process as above.
In FIGS. 1A-C showing the process of making h) type alkaline batteries such as LR6 using mixture 1, 2 is a positive electrode can whose inner periphery is coated with a conductive film 3, and 4 is a polypropylene sheet p+ = Separator made of Rohan etc., 51J, with a gelling agent such as CMC or sodium polyacrylate; n mark dispersed in a -C gel state by electrolytic dipping in Flukali, 6
is a negative (Φ current collector i, 8) with one end welded to the negative terminal plate 7
is a sealing gasket made of polypropylene or polyethylene/Jll. To apply the conductive film 3, conductive film 3, which is made by dissolving carbon or acetylene liquid in 81 fat such as ρvC and a solvent such as benzene, is applied to the inner circumferential surface of the positive electrode can. If you dry it and evaporate only the solvent \゛), then J. As for the specific manufacturing process, first, as shown in FIG. 1, 1 Akebono mixture 1 is inserted into the positive electrode can 2 with the side from which the mold is taken out facing upward, and the state shown in FIG. 1B is obtained. When the insertion is completed, pressurize the positive electrode again by pressing the upper surface between the positive electrodes with an appropriate jig with a center bottle inserted into the positive electrode mixture hollow part, as shown in Figure 1C. Then, the outer periphery of the positive electrode mixture 1 is brought into close contact with the inner surface of the positive electrode can 2.

At this time, the interposition of the conductive film 3 increases the recaro pressure by 721
'i Even if you do not make it large, the positive mixer 1, positive electrode can 2, and IJ will be reliably reduced. Positive combination agent 1 re! After the A pressure is completed, the negative electrode 5 is housed inside the positive electrode mixture 1 via the separator 4, and then the negative electrode collection 1 rod 6 is melted) and the square Kyokutoden rod 6 is sealed with a gasket 1-8. Attach the negative electrode terminal plate 7 with the boss part fitted to the iE electrode can opening 2a, and squeeze and curl the opening 2a of the positive electrode to make the cylindrical alkaline battery shown in the first diagram. .

Next, by molding the positive electrode mixture 1 into a tapered shape as described above, the graphite ratio of the positive electrode mixture 1 to 11 can be as low as −σ or even higher. The following experiment is explained below.This experiment involved making various LRe type batteries using cathode cans coated with a conductive Ii film and varying the graphite ratio (deuterium 4%) of the positive t4 mixture. , environment about them! rgI20'
Under the conditions of C, the short circuit current value (A), and 10Ωj and 'fk
Final voltage 0.9 when performing continuous discharge with 75Ω
The respective discharge times (Hr) up to V were measured. The results are shown in the table below.

Graphite ratio Class 18 current 10Ω continuous discharge
75Ω continuous discharge (↓%) (△) Time (Hr) Time (Hr) 12.5TS, 2
13.0 117+0.0
14.0 14.2 1208,
OD, 6 15.6 130G, O
+3.0 15.8 1323.0
12.8 15.0 1
301.5 2.0 +, 5
From the results of 33L, the graphite ratio was set to 3.
~8%, the internal resistance of the battery determined from the short-circuit current is 10% as the graphite ratio, which is the same as that of conventional batteries.
It is not as large as ζ compared to the case of 12,511%, and it is possible to have a smaller discharge capacity than in the case of conventional i@cells, and therefore it is possible to improve the discharge performance of 11 cells. I understand. The reason for this is that if the graphite ratio is less than 3% by weight, the conductivity within the positive electrode mixture will be 31%. <decreased, and if it is 8% by weight or more, the light 1
f) The content of manganese dioxide, which participates in the u reaction, is reduced.

<Effect of the invention> Cylindrical shape of this invention? The Lua J battery has an Ibi structure using a positive electrode mixture molded with the outside diameter on the mold extraction side tapered larger than the outside diameter on the opposite side, so when removing the positive electrode mixture from the mold, In this case, the spreading force of the positive electrode mixture itself can be effectively suppressed, and mixture DI leakage due to springback can be eliminated. Therefore, Tadashi! l
f! Since the molding pressure of the mixture can be increased to increase the degree of charging of the positive electrode mixture, the electric capacity of the battery can be improved and its discharge performance can be improved. In addition, if the inner surface of the positive electrode can is coated with a conductive Ti pattern, the positive electrode mixture and the positive electrode can can be reliably brought into close contact even if the re-pressing force is small. This can eliminate the deformation of the can.

Furthermore, since the positive electrode mixture was made into a tapered shape as described above,
The graphite ratio can be lowered and the mixture can be molded without any damage, and the graphite ratio is significantly lower than conventional methods, for example, in an alkaline manganese battery, it is 3 to 8%. Therefore, the capacity of the battery can be further improved by increasing the content of the positive electrode active material. Therefore, the present invention is particularly effective for small cylindrical alkaline batteries such as LR6, 03, 1, etc. In addition, by reducing springback when the positive electrode mixture is released from the mold, damage to the mold and decrease in productivity of the positive electrode mixture due to mixture v1 can be significantly reduced, making it possible to reduce battery Another advantage is that it leads to cost reduction.

[Brief explanation of the drawing]

Figures 1A-D are explanatory diagrams showing an example of the manufacturing process of the embodiment of this invention, Figure 2 A1C is an explanatory diagram showing the manufacturing process of the positive electrode mixture used in the example, and Figure 3 is the positive electrode. It is a sectional view showing a mixture. 1.21... Positive electrode stand ~ 1.2... Positive electrode can, 3...
Conductive I19.5... Negative electrode, 7... Negative field terminal plate, 10...
...Mold, 11...Upper bunch, 12...Lower punch. Figure 2 (B) Figure 3 (C)

Claims (1)

[Scope of Claims] 1. A positive electrode mixture is inserted into the positive electrode can, the outer diameter of which is approximately the same as the inner diameter of the positive electrode can on the mold extraction side, and the outer diameter of the opposite side is smaller than the inner diameter of the positive electrode can. A cylindrical alkaline battery characterized in that the positive electrode can is brought into close contact with the inner surface of the positive electrode can by repressurizing the positive electrode can. 2. The cylindrical alkaline battery according to claim 1, wherein the inner surface of the positive electrode can is coated with a conductive film. 3. The cylindrical alkaline battery according to claim 1 or 2, wherein the ratio of graphite to the total of manganese dioxide and graphite in the positive electrode mixture is 3 to 8% by weight. .