JPH05266888A - Alkaline battery - Google Patents

Abstract

PURPOSE:To provide an alkaline battery improved in terms of the moldability of a pellet used for a positive electrode mix. CONSTITUTION:An alkaline battery has manganese dioxide as a positive electrode active material used for a positive electrode mix 1, and a gelated negative electrode 2 using zinc alloy powder as a negative electrode active material and comprising the mixture of the powder with a gelated alkaline electrolyte. The electrolytic current density of the manganese dioxide for the mixture is 2 to 3-A/m<2>, compared with 0.5 to 1.2A/m<2> pertaining to ordinary manganese dioxide, and the mixing rate thereof is 20 to 40wt% relative to the ordinary manganese dioxide. As a result, the moldability of a pellet can be improved without any drop of discharge performance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkaline battery, and more particularly to an alkaline battery in which manganese dioxide having a different electrolysis current density is mixed with a positive electrode active material to improve the moldability of a pellet formed by pressing the manganese dioxide.

[0002]

2. Description of the Related Art Conventionally, in this type of alkaline battery,
A carbon material, mainly 5 to 15% by weight of graphite was added to manganese dioxide which is a positive electrode active material to obtain a positive electrode mixture, which was used in a cylindrical battery under pressure molding.

[0003]

However, since such a pressure-molded positive electrode material mixture pellet has a large filling amount, its strength cannot be sufficiently obtained unless high-pressure molding is performed, so that the battery is assembled. During the process, especially in the pellet transportation process, the pellets may be crushed due to collision between the pellets. Further, if high pressure molding is performed to solve this problem, a considerable load is applied to the molding machine.

The present invention solves such a problem by improving the strength of the positive electrode material mixture pellet without increasing the molding pressure of the positive electrode material mixture pellet and without impairing the discharge characteristics of the battery. It is an object of the present invention to provide an alkaline battery that solves the above problem.

[0005]

In order to solve this problem, the alkaline battery of the present invention is an alkaline battery using manganese dioxide as a positive electrode active material, a zinc alloy powder as a negative electrode active material, and an alkaline aqueous solution as an electrolyte. As an active material, electrolytic manganese dioxide having an electrolytic current density of 0.5 to 1.2 A / m ² and electrolytic manganese dioxide of 2.0 to 3.0 A / m ² were mixed in a weight ratio of 20 to 40% by weight. A positive electrode mixture is used.

[0006]

With this structure, as the positive electrode active material, electrolytic manganese dioxide having an electrolytic current density of 0.5 to 1.2 A / m ² is used in a weight ratio of electrolytic manganese dioxide of 2.0 to 3.0 A / m ^2. By mixing in the range of 20 to 40% by weight to form the positive electrode mixture, it becomes possible to improve the strength of the pressed positive electrode mixture pellets and solve the problem in the battery assembly process. This effect is not fully understood, but it is presumed as follows.

When the electrolytic current density of manganese dioxide is increased, the manganese dioxide is not dense and is in a rough state, so that the surface area is increased. As a result, the unevenness of the surface of manganese dioxide is increased, and when the positive electrode mixture is pressure-molded into pellets, the contactability between manganese dioxides is improved and the strength thereof is improved.

As described above, according to the present invention, manganese dioxide, which is a positive electrode active material, is mixed with manganese dioxide electrolyzed at an electrolysis current density higher than its electrolysis current density, and the mixture is used as a positive electrode mixture. It becomes possible to solve the problems in the transportation process of the molded pellets.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An alkaline battery according to an embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a positive electrode mixture, 2 is a gelled negative electrode, 3 is a separator, 4 is a current collector, 5 is a positive electrode cap, 6 is a metal case, 7 is a battery outer can, and 8 is a resin sealing body. , 9 are bottom plates. First, the effect of improving the strength of the pressure-molded pellets shown in FIG. 2 and the effect on the discharge characteristics were examined with respect to the electrolytic current density and mixing rate of manganese dioxide. First, the effect of improving the strength of the pellet will be described.

In the experimental method, pressure-molded pellets were prepared at a constant molding pressure shown in FIG. 2, and pressure was applied from the side of the electrolyzed pellets to measure the pressure when the pellets were broken. The manganese dioxide electrolytic current density to be mixed is 0.5 to 1.2 A / m ² of manganese dioxide (A), and the mixing ratio is 2,3,4 A / m ² of electrolytic manganese dioxide (B). : B = 10: 0, 9: 1,
It was changed to 8: 2, 6: 4, 4: 6, 0:10. The results of measuring the pressure at the time of breaking are shown in Table 1.

[0012]

[Table 1]

Here, the numbers in the table represent the pressure when the current manganese dioxide was molded into pellets and the pellets were broken.
It is set to 0 and the index for this is shown. As is clear from Table 1, the pressure at the time of breakage of the pressure-molded pellets increases as the electrolytic current density for electrolyzing manganese dioxide increases. Regarding the mixing ratio, a mixing ratio of 10% by weight or less
No difference was found in the pressure when the pellets were broken even if the electrolytic current density was increased. However, when the mixing ratio is increased to 20% by weight or more, there is a difference in pressure when the pellets are broken. It can be seen that the pressure when the pellets are broken increases as the mixing ratio increases.

This tendency was the same when the electrolytic current density of the electrolytic manganese dioxide A was 0.5 and 1.2 A / m ² . Next, the influence on the discharge performance will be described. As an experimental method, the alkaline battery shown in FIG. 1 was prototyped, and the battery was discharged to examine the influence on the characteristics. Also,
The mixed manganese dioxide electrolysis current density is 0.5 A / m.
² mixing ratio for ~1.2A / m ² of electrolytic manganese dioxide (A) for each of the electrolytic manganese dioxide of 2,3,4A / m ² (B) is A: B = 10: 0,9: 1,
It was changed to 8: 2, 6: 4, 4: 6, 0:10. The results of the discharge performance at this time are shown in Table 2.

[0015]

[Table 2]

Here, the numbers in the table indicate the characteristics when the current manganese dioxide is molded into pellets and the pellets are discharged.
It is set to 0 and the index for this is shown. As is clear from Table 2, the discharge characteristics are lowered as the electrolytic current density for electrolyzing manganese dioxide is increased. With respect to the mixing ratio of 10% by weight or less, no influence on the electrolytic current density is shown, but when the mixing ratio is 20% by weight or more, a difference is observed depending on the electrolytic current density.
Looking at each electrolytic current density, when the electrolytic current density is in the range of 2 to 3 times that of the current one, the mixing ratio is 20 to 40.
No influence on the discharge performance is observed in the range of wt%, but the influence is beginning to appear at higher mixing ratios. Next, when the electrolysis current density is four times that of the current one, it can be seen that the mixing ratio of 20% by weight or more affects the discharge performance. This tendency was the same when the electrolytic current densities of the electrolytic manganese dioxide of A were 0.5 and 1.2 A / m ² . Judging from the above, in this example, manganese dioxide as the positive electrode active material was mixed with manganese dioxide having different electrolytic current densities, and the electrolytic current density was 2 to 3 times the electrolytic current density of ordinary manganese dioxide. In the range, the mixing ratio is preferably in the range of 20 to 40% by weight as compared with ordinary manganese dioxide.

[0017]

As is apparent from the above description of the embodiments, according to the alkaline battery of the present invention, an alkaline battery using manganese dioxide as a positive electrode active material, zinc alloy powder as a negative electrode active material, and an alkaline aqueous solution as an electrolytic solution. In the positive electrode active material, electrolytic manganese dioxide having an electrolytic current density of 0.5 to 1.2 A / m ² and electrolytic manganese dioxide of 2.0 to 3.0 A / m ^{2 in} a weight ratio of 20 to 40% are used. By using the positive electrode mixture mixed in the range, it is possible to obtain the effect of improving the strength of the pressed positive electrode mixture pellet without impairing the discharge characteristics of the battery and solving the problem in the battery assembly process.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an alkaline battery according to an embodiment of the present invention.

FIG. 2 is a perspective view of a pellet used for the positive electrode mixture.

[Explanation of symbols]

 1 Positive Electrode Mixture 2 Gel Negative Electrode 3 Separator

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shuji Tsuchida 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Junichi Asaoka, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor, Wako Jibiki, 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. An alkaline battery comprising manganese dioxide as a positive electrode active material, and a gelled negative electrode prepared by mixing zinc alloy powder as a negative electrode active material with a gelled alkaline electrolyte, which has an electrolytic current density. Is from 2.0 to 3.0 A / m ² with respect to electrolytic manganese dioxide of 0.5 to 1.2 A / m ^2.
An alkaline battery provided with a positive electrode active material in which the electrolytic manganese dioxide is mixed in a weight ratio of 20 to 40%.