JPH08241708A - Method for producing positive electrode mixture for alkaline manganese battery - Google Patents

Abstract

(57) [Abstract] [Purpose] A method for producing a positive electrode mixture for an alkali manganese battery, in which a desired molding pressure can be obtained at a low pressure, a load on a press molding machine such as a mold is small, and the yield is high. provide. [Structure] Electrolytic manganese dioxide is mixed with graphite as a conductive agent and an additive, and the mixture is granulated and then molded into a predetermined shape by a press molding machine such as a mold. In the manufacturing method, a predetermined amount of the powdery additive is added to the mixture in a predetermined amount as described in the following items. Add potassium hydroxide 3.8 wt% or less Add potassium carbonate 2.9 wt% or less Add potassium chromate 3.1 wt% or less Add sodium hydroxide 1.9 wt% or less Sodium nitrate 2.6 wt % Or less added Sodium thiosulfate added 2.0% by weight or less
Add 2.1% by weight or less of nickel sulfate

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a positive electrode mixture for alkaline manganese batteries.

[0002]

2. Description of the Related Art As a method for producing a positive electrode mixture for use in an alkaline manganese battery, first, materials such as electrolytic manganese dioxide and graphite are mixed, rolled into a plate by a roll rolling machine, and then pulverized and granulated. The positive electrode mixture having a predetermined shape is obtained by press molding with a press molding machine such as a mold.

The positive electrode mixture thus obtained is pressure-molded to form a positive electrode, which is then loaded into a cylindrical alkaline manganese battery case 1 as shown in FIG. To do.

In such a positive electrode mixture, in order to improve the battery performance, it is necessary to fill the limited space in the battery case 1 with the positive electrode as much as possible. Therefore, a predetermined molding density and particle size are required. Met.

Therefore, in order to obtain a desired molding density, an excessive molding pressure is required during press molding.

[0006]

However, in the above-mentioned manufacturing method, since the molding pressure is excessive, the mold deteriorates and wears out sharply, and the life is shortened. Therefore, the mold must be frequently replaced. There was a problem that it had to be.

Further, the ratio of the desired particle size in the positive electrode mixture after granulation, that is, the yield is not high at all, and improvement has been desired.

The present invention is intended to solve the above-mentioned problems, in which a desired molding pressure can be obtained at a low pressure, a load on a press molding machine such as a mold can be reduced, and a high yield can be obtained. An object of the present invention is to provide a method for producing a positive electrode mixture for use.

[0009]

In order to achieve the above object, the present invention provides a press molding machine such as a die after manganese dioxide is mixed with graphite as a conductive agent and an additive, and the mixture is granulated. In the method for producing a positive electrode mixture for an alkaline manganese battery, which is formed into a predetermined shape in (1), a predetermined amount of a powdery additive is added to the mixture in a predetermined amount as described in the following items.

Potassium hydroxide is added in the range of 3.8% by weight or less. Potassium carbonate is added in the range of 2.9% by weight or less. Potassium chromate is added in the range of 3.1% by weight or less. Sodium hydroxide is added in the range of 1.9% by weight or less. Sodium nitrate is added in the range of 2.6% by weight or less. Sodium thiosulfate is added in the range of 2.0% by weight or less. Nickel sulfate is added in the range of 2.1% by weight or less.

[0011]

By adding the powdery additive to the positive electrode mixture, it is possible to obtain a predetermined molding density with a lower molding pressure than before and reduce the load on a press molding machine such as a mold. The yield can be improved.

The above mechanism is as described below.

Since the powdery additive absorbs water existing on the surface of particles such as manganese dioxide and graphite, its viscosity increases. The additive having the increased viscosity functions as a binder and intervenes at the boundary between the particles of the positive electrode material mixture to improve the bonding state between the positive electrode material mixture particles and between the positive electrode material mixture particles and between the particle and the mold. Also reduces friction. That is,
The slip of the positive electrode mixture at the time of molding becomes good and the bonding property between the positive electrode mixture particles is also good, so that the compression density is increased even at a low molding pressure and a predetermined molding density can be obtained, and the load on the molding die is reduced. .

Further, even during granulation, the positive electrode mixture has a good slip property and a good bonding property between particles, so that the granulation property is improved and the yield is improved.

[0015]

The first to seventh embodiments of the method for producing a positive electrode mixture for alkaline manganese batteries according to the present invention will be described in detail below with reference to the drawings.

Each of the examples is composed of the following steps, and the kneading step is the main part of the present invention, and the other steps are the same as the conventional ones. Kneading process of mixing and kneading electrolytic manganese dioxide, graphite and powdery additive constituting the positive electrode mixture: The mixture is rolled into a plate using a rolling mill and then finely pulverized to a particle size of 250 to 850 μm. Granulation step of granulating: Molding density of 3.27 to using a mold (press molding machine)
Molding process for molding into ring-shaped pellets at 3.31 g / cc: First, the first embodiment will be described.

In this example, potassium hydroxide was added to the mixture as a powdery additive in the above kneading step in an amount of 0.
It was added at a rate of 2 to 4.0% by weight.

At this time, the ratio of particles having a particle size of 250 to 850 μm in the positive electrode mixture obtained in the above granulation step with respect to the added amount of powdered potassium hydroxide, that is, the yield characteristic was measured. As a result, as shown in FIG. 1 (a), the yield was clearly improved as compared with the conventional case where no additive was added, and particularly at 0.5 wt% or more, the yield could be 60% or more.

Further, the molding density in the above-mentioned molding step with respect to the amount of powdered potassium hydroxide added is 3.27 to 3.31.
The molding pressure characteristics for obtaining g / cc were measured. As a result, as shown in FIG. 1 (b), the molding pressure can be obviously reduced as compared with the conventional case of no addition, and particularly, the molding pressure can be reduced to 0.
When it was 5% by weight or more, the molding pressure could be reduced to about 60% or less of the conventional pressure.

Next, an LR6 type alkaline manganese battery as shown in FIG. 8 was produced by using the positive electrode mixture obtained through the above steps through the following steps. Molding step of press-molding the obtained pellet-shaped positive electrode mixture to form the positive electrode 7. A plurality of positive electrodes 7 are press-fitted into the metal case 1 of the battery to be laminated, and then the separator 6 is fitted to the inner peripheral portion. Steps to be performed: Steps of injecting an electrolytic solution composed of an aqueous solution of potassium hydroxide and leaving it for a predetermined time: Steps of injecting the gelled zinc negative electrode 5: Assembly steps of sealing the opening of the case 1 of the alkaline manganese battery:

The discharge duration characteristics of the alkaline manganese battery thus obtained with respect to the amount of powdery potassium hydroxide added were measured, and the results shown in the graph of FIG. 1 (c) were obtained. This measurement was carried out for each of 54 alkaline manganese batteries prepared corresponding to the parameters corresponding to each point plotted by a black dot in the graph. The discharge duration at this time was the first continuous discharge time when the load was 10 ohms at a temperature of 20 ° C. and the final voltage was 0.90 V. As a result, the continuous discharge duration is 17.2 hours or more in the range where the amount of powdered potassium hydroxide added is 3.8% by weight or less.
In consideration of the above results of (a) and (b), the added amount in this range is preferable for practical use.

Next, a second embodiment will be described.

In this example, potassium carbonate was added to the mixture in an amount of 0.2 as a powdery additive in the kneading step.
Was added in a proportion of ˜4.0% by weight.

At this time, the yield characteristics of the positive electrode mixture obtained in the above granulation step were measured with respect to the amount of powdered potassium carbonate added. As a result, as shown in FIG. 2 (a), the yield was clearly improved as compared with the conventional case where no additive was added.
When it was 5% by weight or more, the yield could be 60% or more.

Further, the molding density in the above-mentioned molding step with respect to the amount of powdered potassium carbonate added is 3.27 to 3.31 g.
The molding pressure characteristic for obtaining / cc was measured. As a result, as shown in FIG. 2 (b), the molding pressure can be clearly reduced as compared with the conventional case where no additive is added.
When it was 5% by weight or more, the molding pressure could be reduced to about 60% or less of the conventional pressure.

Then, an LR6 type alkaline manganese battery was produced in the same manner as in the first embodiment, using the positive electrode mixture obtained through the above steps (1) to (3).

The discharge duration characteristics of the obtained alkaline manganese battery with respect to the amount of powdered potassium carbonate added were measured under the same conditions as in the first embodiment. As a result, the measurement result as shown in FIG. 2 (c) was obtained, and the continuous discharge duration was 17.2 hours or more because the amount of powdered potassium carbonate added was 2.9.
The range is less than or equal to wt%, and in view of the above results of FIGS.

Next, a third embodiment will be described.

In the present example, potassium chromate was added as a powdery additive in the above kneading step in a proportion of 0.2 to 4.0% by weight with respect to the mixture.

At this time, the yield characteristics of the positive electrode mixture obtained in the above granulation step were measured with respect to the amount of powdered potassium chromate added. As a result, as shown in FIG. 3 (a), the yield was clearly improved as compared with the conventional case where no additive was added, and the yield could be 60% or more especially at 0.5% by weight or more.

Further, the molding density in the above molding step with respect to the amount of powdered potassium chromate added is 3.27 to 3.3.
The molding pressure characteristic for obtaining 1 g / cc was measured. As a result, as shown in FIG. 3 (b), the molding pressure can be clearly reduced as compared with the conventional non-added case, and particularly at 0.5% by weight or more, the molding pressure becomes about 60% or less of the conventional one. Could be lowered.

Next, an LR6 type alkaline manganese battery was prepared in the same manner as in the first embodiment, using the positive electrode mixture obtained through the above steps (1) to (3).

The discharge duration characteristics of the obtained alkaline manganese battery with respect to the added amount of powdered potassium chromate were measured under the same conditions as in the first embodiment. As a result, FIG. 3 (c)
The measurement results shown in Fig. 1 are obtained and the continuous discharge duration is 1
7.2 hours or more is the range in which the amount of powdered potassium chromate added is 3.1% by weight or less, as shown in FIG.
In consideration of the above result of (b), the addition amount in this range is preferable in practical use.

Next, a fourth embodiment will be described.

In this example, sodium hydroxide was added as a powdery additive in the above-mentioned kneading step in a proportion of 0.2 to 4.0% by weight with respect to the mixture.

At this time, the yield characteristics of the positive electrode mixture obtained in the above granulation step were measured with respect to the amount of powdered sodium hydroxide added. As a result, as shown in FIG. 4 (a), the yield was clearly improved as compared with the conventional case where no additive was added, and particularly when the amount was 0.5 wt% or more, the yield could be 60% or more.

Further, the molding density in the above molding step with respect to the amount of powdered sodium hydroxide added is 3.27 to 3.3.
The molding pressure characteristic for obtaining 1 g / cc was measured. As a result, as shown in FIG. 4 (b), the molding pressure can be clearly reduced as compared with the conventional non-added case, and particularly at 0.5% by weight or more, the molding pressure can be reduced to about 60% or less of the conventional case. Could be lowered.

Then, an LR6 type alkaline manganese battery was produced in the same manner as in the first embodiment, using the positive electrode mixture obtained through the above steps (1) to (3).

The discharge duration characteristics of the obtained alkaline manganese battery with respect to the added amount of powdery sodium hydroxide were measured under the same conditions as in the first embodiment. As a result, FIG. 4 (c)
The measurement results shown in Fig. 1 are obtained and the continuous discharge duration is 1
7.2 hours or more is the range in which the amount of powdered sodium hydroxide added is 1.9% by weight or less, as shown in FIG.
In consideration of the above result of (b), the addition amount in this range is preferable in practical use.

Next, a fifth embodiment will be described.

In this example, sodium nitrate was added to the mixture as a powdery additive in the above kneading step in an amount of 0.
It was added at a rate of 2 to 4.0% by weight.

At this time, the yield characteristics of the positive electrode mixture obtained in the above granulation step were measured with respect to the amount of powdered sodium nitrate added. As a result, as shown in FIG. 5 (a), the yield was clearly improved as compared with the conventional case where no additive was added, and the yield could be 55% or more especially at 0.5 wt% or more.

Also, the molding density in the above-mentioned molding step with respect to the amount of powdered sodium nitrate added is 3.27 to 3.31.
The molding pressure characteristics for obtaining g / cc were measured. As a result, as shown in FIG. 5 (b), the molding pressure can be clearly reduced as compared with the conventional case where no additive is added.
When it was 5% by weight or more, the molding pressure could be reduced to about 60% or less of the conventional pressure.

Next, an LR6 type alkaline manganese battery was produced in the same manner as in the first embodiment, using the positive electrode mixture obtained through the above steps (1) to (4).

The discharge duration characteristics of the obtained alkaline manganese battery with respect to the addition amount of powdery sodium nitrate were firstly examined.
It measured on the same conditions as an Example. As a result, the measurement result as shown in FIG. 5C was obtained, and the continuous discharge duration was 17.
It is in the range of 2.6% by weight or less of the powdered sodium nitrate for 2 hours or more, and in practical use, the addition amount in this range is preferable together with the results of FIGS. 5 (a) and 5 (b). .

Next, a sixth embodiment will be described.

In this example, sodium thiosulfate was added as a powdery additive in the above-mentioned kneading step at a ratio of 0.2 to 4.0% by weight to the mixture.

At this time, the yield characteristics of the positive electrode mixture obtained in the above granulation step were measured with respect to the amount of powdered sodium thiosulfate added. As a result, as shown in FIG. 6 (a), the yield was clearly improved as compared with the conventional case of no addition, and the yield could be 55% or more especially at 0.5% by weight or more.

Further, the molding density in the above molding step with respect to the added amount of powdery sodium thiosulfate is 3.27 to 3.
The molding pressure characteristics for obtaining 31 g / cc were measured. As a result, as shown in FIG. 6 (b), the molding pressure can be clearly reduced as compared with the conventional non-added case, and particularly at 0.5% by weight or more, the molding pressure becomes about 70% or less of the conventional case. Could be lowered.

Then, an LR6 type alkaline manganese battery was prepared in the same manner as in the first embodiment, using the positive electrode mixture obtained through the above steps (1) to (3).

The discharge duration characteristics of the obtained alkaline manganese battery with respect to the added amount of powdery sodium thiosulfate were measured under the same conditions as in the first embodiment. As a result, FIG.
The measurement results as shown in (c) are obtained, and the continuous discharge duration is 17.2 hours or more in the range where the amount of the powdery sodium thiosulfate added is 2.0 wt% or less.
In consideration of the above results of (a) and (b), the added amount in this range is preferable for practical use.

Next, a seventh embodiment will be described.

In this example, nickel sulfate was added to the mixture as a powdery additive in an amount of 0.2 in the kneading step.
Was added in a proportion of ˜4.0% by weight.

At this time, the yield characteristics of the positive electrode mixture obtained in the above granulation step were measured with respect to the amount of powdered nickel sulfate added. As a result, as shown in FIG. 7 (a), the yield is clearly improved as compared with the conventional case where no additive is added, and in particular,
When it was 5% by weight or more, the yield could be 55% or more.

Further, the molding density in the above-mentioned molding step with respect to the addition amount of powdered nickel sulfate is 3.27 to 3.31 g.
The molding pressure characteristic for obtaining / cc was measured. As a result, as shown in FIG. 7 (b), the molding pressure can be obviously reduced as compared with the conventional case of no addition, and particularly, the pressure of 0.
When it was 5% by weight or more, the molding pressure could be lowered to about 70% or less of the conventional pressure.

Then, an LR6 type alkaline manganese battery was produced in the same manner as in the first embodiment, using the positive electrode mixture obtained through the above steps (1) to (5).

The discharge duration characteristics of the obtained alkaline manganese battery with respect to the amount of powdered nickel sulfate added were measured under the same conditions as in the first embodiment. As a result, the measurement result as shown in FIG. 7C was obtained, and the continuous discharge duration was 17.2.
More than the time is because the addition amount of powdered nickel sulfate is 2.
The amount added is in the range of 1% by weight or less, and in view of the results shown in FIGS.

As described in each of the above examples, when the powdery additive is added to the positive electrode mixture, the additive absorbs water present on the surface of particles such as manganese dioxide and graphite, and the viscosity thereof increases. . The additive having the increased viscosity functions as a binder and intervenes at the boundary between the particles of the positive electrode material mixture to improve the bonding state between the positive electrode material mixture particles and between the positive electrode material mixture particles and between the particle and the mold. Also reduces friction. That is, the slip of the positive electrode mixture at the time of molding becomes good and the bonding property between the positive electrode mixture particles is also good, so that the compression density is increased even at a low molding pressure and a predetermined molding density can be obtained, and the load on the molding die is reduced. Reduce.

Further, even during granulation, the positive electrode mixture has a good slip property and a good bonding property between particles, so that the granulation property is further improved and the yield is improved.

Furthermore, the discharge performance of the alkaline manganese battery using the positive electrode mixture manufactured by the method of this embodiment is not impaired in practical use.

Even if the powdery additive of each example is mixed in the positive electrode mixture in the state of an aqueous solution, the same effect as the present invention cannot be obtained. That is, during molding, water in the positive electrode mixture exudes to the boundary surface between the mold and the compressed positive electrode mixture, so that friction between the mold and the positive electrode mixture increases. In order to mold against this friction, the molding pressure must be increased and cannot be kept low. Therefore, the load on the mold cannot be reduced.

[0062]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the powdered additive is added to the positive electrode mixture, so that the following performance can be achieved without impairing the discharge performance of the alkaline manganese battery using this positive electrode mixture. It is possible to exert an effect.

It is possible to reduce deterioration and wear of a press molding machine such as a die and improve productivity.

Further, the yield of the positive electrode mixture can be improved and the yield can be improved.

[Brief description of drawings]

FIG. 1 shows the characteristics of a positive electrode mixture and an alkaline manganese battery using the same with respect to the amount of powdery potassium hydroxide added according to the present invention, where (a) is yield characteristics, (b) is molding pressure characteristics, and c) shows discharge duration characteristics.

FIG. 2 shows the characteristics of the positive electrode mixture and the alkaline manganese battery using the same with respect to the amount of powdery potassium carbonate added according to the present invention, where (a) is yield characteristics, (b) is molding pressure characteristics, and (c) is ) Indicates discharge duration characteristics.

FIG. 3 shows the characteristics of the positive electrode mixture and the alkaline manganese battery using the same with respect to the amount of powdered potassium chromate added according to the present invention, (a) showing yield characteristics, (b) forming pressure characteristics, c) shows discharge duration characteristics.

FIG. 4 shows characteristics of a positive electrode mixture and an alkaline manganese battery using the same with respect to the amount of powdery sodium hydroxide added according to the present invention, where (a) is a yield characteristic, (b) is a molding pressure characteristic, and c) shows discharge duration characteristics.

5 shows characteristics of a positive electrode mixture and an alkaline manganese battery using the same with respect to the amount of powdery sodium nitrate added according to the present invention, (a) showing yield characteristics, (b) forming pressure characteristics, and (c). ) Indicates discharge duration characteristics.

FIG. 6 shows the characteristics of the positive electrode mixture and the alkaline manganese battery using the same with respect to the amount of powdery sodium thiosulfate according to the present invention, where (a) is yield characteristics, (b) is molding pressure characteristics, and c) shows discharge duration characteristics.

FIG. 7 shows the characteristics of a positive electrode mixture and an alkaline manganese battery using the same with respect to the amount of powdered nickel sulfate added according to the present invention, (a) showing yield characteristics, (b) forming pressure characteristics, and (c) ) Indicates discharge duration characteristics.

FIG. 8 is a vertical cross-sectional view of a cylindrical alkaline manganese battery using a positive electrode mixture according to a conventional manufacturing method and a manufacturing method according to the present invention.

[Explanation of symbols]

 1 Battery Case 3 Sealing Gasket 1a Conductive Film 4 Current Collector 1b Meta Label 5 Gel Zinc Negative Electrode 1c Insulating Washer 6 Separator 2 Negative Terminal Plate 7 Positive Electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kuniyoshi Nishida 5 36-11 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. (72) Inventor Takeshi Mochizuki 5 36-11 Shimbashi, Minato-ku, Tokyo Fuji Electrochemical Co., Ltd.

Claims (7)

[Claims] 1. A positive electrode mixture for an alkaline manganese battery, which is obtained by mixing manganese dioxide with graphite as a conductive agent and an additive, granulating the mixture, and then molding the mixture into a predetermined shape with a press molding machine such as a mold. Alkali manganese, characterized in that, in the method for producing, the powdery potassium hydroxide is added to the mixture as the additive, and the addition amount is within the range of 3.8% by weight or less with respect to the mixture. A method for producing a positive electrode mixture for a battery. 2. A positive electrode mixture for an alkali manganese battery, which is obtained by mixing manganese dioxide with graphite as a conductive agent and an additive, granulating the mixture, and then molding the mixture into a predetermined shape with a press molding machine such as a mold. In the method for producing an alkaline manganese battery, the powdery potassium carbonate as an additive is added to the mixture, and the addition amount is within the range of 2.9% by weight or less with respect to the mixture. For manufacturing a positive electrode mixture for use. 3. A positive electrode mixture for an alkaline manganese battery, which is obtained by mixing manganese dioxide with graphite as a conductive agent and an additive, granulating the mixture, and then molding the mixture into a predetermined shape with a press molding machine such as a mold. In the method for producing the same, powdery potassium chromate is added to the mixture as the additive, and the addition amount is in the range of 3.1% by weight or less with respect to the mixture. A method for producing a positive electrode mixture for a battery. 4. A positive electrode mixture for an alkaline manganese battery, which is obtained by mixing manganese dioxide with graphite as a conductive agent and an additive, granulating the mixture, and then molding the mixture into a predetermined shape with a press molding machine such as a mold. In the method for producing an alkaline manganese powder according to claim 1, powdery sodium hydroxide is added to the mixture as the additive, and the addition amount is within the range of 1.9% by weight or less with respect to the mixture. A method for producing a positive electrode mixture for a battery. 5. A positive electrode mixture for an alkaline manganese battery, which is obtained by mixing manganese dioxide with graphite as a conductive agent and an additive, granulating the mixture, and then molding the mixture into a predetermined shape with a press molding machine such as a mold. In the method for producing an alkaline manganese battery according to claim 1, powdery sodium nitrate is added to the mixture as the additive, and the addition amount is in the range of 2.6% by weight or less with respect to the mixture. For manufacturing a positive electrode mixture for use. 6. A positive electrode mixture for an alkaline manganese battery, which is obtained by mixing manganese dioxide with graphite as a conductive agent and an additive, granulating the mixture, and then molding the mixture into a predetermined shape with a press molding machine such as a mold. In the method for producing an alkaline manganese powder, sodium thiosulfate in the form of powder is added to the mixture as the additive, and the amount of addition is 2.0% by weight or less based on the mixture. A method for producing a positive electrode mixture for a battery. 7. A positive electrode mixture for an alkaline manganese battery, which is obtained by mixing manganese dioxide with graphite as a conductive agent and an additive, granulating the mixture, and then molding the mixture into a predetermined shape with a press molding machine such as a mold. In the method for manufacturing an alkaline manganese battery according to claim 1, powdered nickel sulfate as the additive is added to the mixture, and the addition amount is 2.1% by weight or less with respect to the mixture. For manufacturing a positive electrode mixture for use.