JP4767978B2 - Alkaline battery - Google Patents

Description

  The present invention relates to an alkaline dry battery that is excellent in positive electrode utilization rate in heavy load and medium load discharge and in which a decrease in electric capacity in light load discharge is suppressed.

With recent progress and development of portable information devices such as mobile phones, alkaline dry batteries capable of heavy load discharge are desired.
On the other hand, in conventional alkaline batteries, anatase-type titanium oxide (for example, Patent Document 1), titanium-containing composite oxide (for example, Patent Document 2), sulfuric acid are used as positive electrode additives in order to improve heavy load discharge characteristics. A barium compound such as barium (for example, Patent Document 3) is used.
Japanese translation of PCT publication No. 8-510355 JP-A-9-139201 International Publication No. 00/30198 Pamphlet

However, when titanium oxide, a titanium-containing composite oxide or a barium compound is added to the positive electrode, the heavy load discharge characteristics are improved to some extent, but the active material utilization rate is not sufficient. Moreover, in order to make the effect of the conventional additive sufficient, it is necessary to use a large amount of additive. Therefore, the filling amount in the positive electrode of the manganese dioxide which is an active material falls, there exists a problem that the electrical capacity of a battery falls and a light load discharge characteristic will reduce. This is very inconvenient for use in devices that require light load discharge, such as watches, because the demand for alkaline batteries is still not small.
An object of the present invention is to provide an alkaline dry battery that is excellent in a heavy load discharge characteristic and a medium load discharge characteristic and in which a decrease in light load discharge characteristic is suppressed.

In order to solve the above problems, the present invention provides an alkaline dry battery comprising a negative electrode, an alkaline electrolyte, and a positive electrode containing manganese dioxide and graphite powder, wherein the positive electrode contains Ti (OH) ₄ as an additive. An alkaline dry battery comprising 0.01 to 5 parts by weight per 100 parts by weight is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the alkaline dry battery which was excellent in the heavy load discharge characteristic and the medium load discharge characteristic, and the fall of the light load discharge characteristic was suppressed can be provided.

The present invention increases the utilization rate of the positive electrode active material in heavy load or medium load discharge by including at least one selected from the group consisting of Ti (OH) ₄ and TiO (OH) ₂ in the positive electrode.
On the other hand, when the above additives are added to the positive electrode, the proportion of the positive electrode active material in the positive electrode mixture decreases, but these additives have a function as a binder, and the addition of the positive electrode mixture The filling property is improved, and the filling amount of the positive electrode is increased under the same molding conditions. Therefore, even if the above additives are added, the filling amount of the positive electrode active material does not decrease within the range of the addition amount in the present invention, and the decrease in light load discharge characteristics is suppressed.

That is, the positive electrode in the present invention includes at least one selected from the group consisting of manganese dioxide as a positive electrode active material, graphite powder as a conductive agent, and Ti (OH) ₄ and TiO (OH) _{2 as} additives. Characterized by points.
When these additives are contained in the positive electrode, the retention of the electrolytic solution in the positive electrode active material is improved, so that an increase in internal resistance caused by insufficient supply of the electrolytic solution into the positive electrode active material at the end of discharge occurs. It is considered that a rapid voltage drop at the end of discharge is suppressed.

TiO (OH) ₂ in the present invention is in the form of fine powder having an average particle size of 10 ⁻⁹ to 10 ⁻⁸ m, and the particle size (10 ⁻⁷ ) of anatase titanium oxide conventionally used as an additive for the positive electrode. ^10-5 m), and when a certain amount of TiO (OH) ₂ is added in the positive electrode, the contact area with the positive electrode active material is larger. Therefore, by adding a small amount of TiO (OH) ₂ , an effect more than conventional can be obtained, which is preferable as an additive.

If it exceeds 10 ⁻⁸ m, the surface area of the particles becomes small, and the effect is reduced.
Further, when these additives are added to a mixture composed of manganese dioxide and graphite, they also act as a binder, and have the effect of improving the formability of the positive electrode and increasing the filling amount.

The positive electrode preferably contains 0.01 to 5 parts by weight of at least one selected from the group consisting of Ti (OH) ₄ and TiO (OH) ₂ per 100 parts by weight of manganese dioxide. If the amount is less than 0.01 parts by weight, the improvement of the heavy load and light load discharge characteristics is insufficient, and if the amount exceeds 5 parts by weight, the light load discharge characteristics deteriorate. Furthermore, it is particularly preferable to contain 0.5 to 3 parts by weight per 100 parts by weight of manganese dioxide.

  Conventionally used manganese dioxide and graphite powder may be used. Further, conventional negative electrodes and alkaline electrolytes can also be used.

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these examples.
<< Examples 1-3 and Reference Examples 1-2 >>
FIG. 1 is a front view showing a cross section of a part of an alkaline battery produced in an example of the present invention.
In FIG. 1, a positive electrode mixture 2, a gelled negative electrode 3, and a separator 4 formed in a short cylindrical pellet are housed inside a battery case 1. As the battery case 1, a steel case having an inner surface plated with nickel can be used. On the inner surface of the battery case 1, a plurality of positive electrode mixtures 2 are accommodated in close contact. A separator 4 is disposed further inside the positive electrode mixture 2, and a gelled negative electrode 3 is filled therein.

The positive electrode mixture 2 was produced as follows.
First, manganese dioxide and graphite are mixed at a weight ratio of 90:10, and further, Ti (OH) ₄ is added to a predetermined amount (x parts by weight) shown in Table 1 per 100 parts by weight of manganese dioxide. , Mixed. The average particle size of Ti (OH) ₄ used in this example was 10 ⁻⁶ m. After adding 3 parts by weight of alkaline electrolyte per 100 parts by weight of the obtained mixture and stirring sufficiently, it was compression molded into flakes. Next, the flaky positive electrode mixture was pulverized into granules, which were classified with a sieve, and those having a 10 to 100 mesh shape were pressure-formed into a hollow cylinder to obtain a pellet-like positive electrode mixture 2. Two of these positive electrode mixtures were inserted into the battery case 1, and the positive electrode mixture 2 was reshaped with a pressurizing jig and was brought into close contact with the inner wall of the battery case 1.

  A bottomed cylindrical separator 4 was placed in the center of the positive electrode mixture 2 placed in the battery case 1 as described above, and a predetermined amount of alkaline electrolyte was injected into the separator 4. After a predetermined time, a gelled negative electrode 3 composed of an alkaline electrolyte, a gelling agent and zinc powder was filled into the separator 4.

As the gelled negative electrode 3, a gel comprising 1 part by weight of sodium polyacrylate as a gelling agent, 33 parts by weight of 40% by weight sodium hydroxide as an alkaline electrolyte and 66 parts by weight of zinc powder was used.
Moreover, the separator 4 used the nonwoven fabric which mixed and mixed mainly the polyvinyl alcohol fiber and the rayon fiber.

Subsequently, the negative electrode current collector 6 was inserted into the center of the gelled negative electrode 3. The negative electrode current collector 6 was integrated with a gasket 5 and a bottom plate 7 that also served as a negative electrode terminal.
And the opening edge part in the battery case 1 was crimped to the peripheral part of the baseplate 7 via the edge part of the gasket 5, and the opening part of the battery case 1 was sealed. Finally, the outer surface of the battery case 1 was covered with the exterior label 8 to obtain an alkaline dry battery.
The obtained alkaline dry battery was evaluated as follows.

[Evaluation]
In order to evaluate the heavy load discharge characteristics, the initial (immediately after production) alkaline dry battery was continuously discharged to a load of 2.2Ω and a final voltage of 0.9 V, and the discharge time at that time was measured. The result of the additive-free alkaline dry battery (Comparative Example 1) was taken as a reference value of 100, and the heavy load discharge characteristics were expressed as an index. The evaluation results are shown in Table 1.
Further, the medium load discharge characteristics were evaluated in the same manner as in the case of the above heavy load discharge characteristics except that continuous discharge was performed with a load of 10Ω. The light load discharge characteristics were evaluated in the same manner as in the case of the heavy load discharge characteristics except that the discharge was continuously performed with a load of 39Ω. These evaluation results are also shown in Table 1.

<< Reference Examples 3-7 >>
In the same manner as in Example 1, except that TiO (OH) ₂ was added in place of the positive electrode additive Ti (OH) _{4 so} as to have a predetermined amount (x parts by weight) shown in Table 1 per 100 parts by weight of manganese dioxide. A positive electrode mixture 2 was produced to obtain an alkaline battery. The battery characteristics of the alkaline battery were evaluated by the same method as in Example 1. The average particle diameter of TiO (OH) ₂ used in this reference example was 10 ⁻⁹ m.

<< Comparative Examples 1-4 >>
The positive electrode mixture was prepared in the same manner as in Example 1 except that TiO ₂ was added in a predetermined amount (x parts by weight) shown in Table 1 per 100 parts by weight of manganese dioxide instead of the positive electrode additive Ti (OH) _4. 2 was prepared to obtain an alkaline battery. The average particle size of TiO ₂ was 10 ⁻⁶ m. The battery characteristics of the alkaline battery were evaluated by the same method as in Example 1.

From Table 1, it can be seen that, when using either Ti (OH) ₄ or TiO (OH) ₂ , the heavy load discharge characteristics of the alkaline battery are excellent when the amount is 0.01 to 5 parts by weight per 100 parts by weight of manganese dioxide. In addition, it can be seen that the light load discharge characteristics are not deteriorated. If the addition amount is small as in Reference Example 1 and Reference Example 3, the effect of improving the utilization ratio of the positive electrode active material cannot be obtained so much that the heavy load discharge characteristics are hardly improved. When the addition amount is too large as in Reference Example 2 and Reference Example 7, light load discharge characteristics are deteriorated.

The characteristic of Reference Example 5 is improved over that of Example 2 with respect to 1 part by weight of the optimum addition amount. This is thought to be because the particle size of TiO (OH) ₂ was as small as 10 ⁻⁹ m, and even when the same amount was added, the contact area with the positive electrode active material was large and the effect of improving the characteristics was great. It is done.
In addition, the same effect can be seen when both Ti (OH) ₄ and TiO (OH) ₂ are mixed and added to the positive electrode.

  The alkaline dry battery of the present invention is suitably used as a power source for electronic devices such as portable devices.

It is the front view which made a part of an example of the alkaline dry battery of the present invention a section.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery case 2 Positive electrode mixture 3 Gel-like negative electrode 4 Separator 5 Gasket 6 Negative electrode current collector 7 Bottom plate 8 Exterior label

Claims (1)

In an alkaline dry battery comprising a negative electrode, an alkaline electrolyte, and a positive electrode containing manganese dioxide and graphite powder, the positive electrode contains 0.01 to 5 parts by weight of Ti (OH) ₄ as an additive per 100 parts by weight of manganese dioxide. An alkaline battery characterized by that.

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