JPH0660869A - Manufacture of manganese dry battery - Google Patents

Abstract

PURPOSE:To improve the short duration of discharge under a light load as a defect characteristic of a positive electrode mix using conventionally and chemically available manganese dioxide by mixing a chemical mix of manganese dioxide with carbon fiber. CONSTITUTION:This is a method for manufacturing a manganese dry battery featuring the preparation of a positive electrode mix through the following processes; natural manganese dioxide is calcined, and manganese oxide available therefrom is immersed in mineral acid solution. Furthermore, the oxide so obtained is water washed, dried and granulated for preparing chemically synthesized manganese dioxide powder. This powder is, then, mixed with carbon fiber prepared through a gaseous phase synthesizing method. Also, the positive electrode active substance obtained by mixing the powder with the carbon fiber is compressed, molded and crushed to manufacture a positive electrode mix as secondary particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a positive electrode of a dry battery using chemically synthesized manganese monoxide, and its object is to improve discharge performance.

[0002]

2. Description of the Related Art Conventionally, as manganese dioxide for manganese dry batteries, which has excellent heavy-load discharge characteristics, there is so-called chemical manganese dioxide produced by subjecting manganese oxides (Mn ₂ O ₃ , Mn ₃ O ₄ ) to acid treatment. It was This chemical manganese dioxide has the same heavy load discharge characteristics as electrolytic manganese dioxide,
It has been attracting attention in recent years because it has more or more properties and may be manufactured at lower cost than electrolytic manganese dioxide. However, in a dry battery of an electrolytic solution containing mainly zinc chloride, although the heavy load discharge characteristics are excellent, conversely, the utilization rate of the chemical manganese dioxide in the light load discharge was not sufficient.

[0003]

In order to improve this light load discharge characteristic, the amount of the electrolytic solution is increased and the compounding ratio of acetylene black which is a conductive material is increased.
However, if the amount of electrolyte is increased, leakage of the battery will occur frequently, and if the amount of conductive material is increased, the amount of chemical manganese dioxide will be reduced accordingly and the light load discharge capacity will decrease. The task was to do so. The present invention solves such problems, and particularly aims to improve the light load discharge characteristics of a manganese dry battery.

[0004]

According to the present invention, a chemically synthesized manganese dioxide powder (CMD) produced by roasting natural manganese dioxide, immersing the obtained manganese oxide in a mineral acid solution, washing with water, drying and granulating. And a carbon fiber produced by a vapor phase synthesis method, and a positive electrode mixture is produced by using the obtained positive electrode active substance, which is a method for producing a manganese dry battery. In addition, the positive electrode mixture may be manufactured by adding a compression molding pulverization step after mixing with the carbon fiber.

The CMD used in the present invention is obtained by roasting natural manganese dioxide ore at 850 ° C. to obtain dimanganese trioxide (Mn ₂ O ₃ ). The Mn ₂ O ₃ obtained here is acid-treated with a mineral acid such as sulfuric acid. When acid treatment is performed with sulfuric acid, chemically synthesized manganese dioxide is produced by the following disproportionation reaction. Mn ₂ O ₃ + H ₂ SO ₄ → MnO ₂ + MnSO ₄ + H ₂ O

The carbon fiber produced by the vapor phase synthesis method used in the present invention is produced by flowing an aliphatic or aromatic hydrocarbon gas into an inert gas atmosphere such as hydrogen gas or argon gas at about 1000 ° C. It is manufactured by dispersing metal particles such as nickel, nickel and cobalt. The characteristics of this fiber are that the conductivity is better than that of conventional acetylene black, and that the liquid absorption is also excellent.

[0007]

The present invention is a CM produced from natural manganese dioxide.
By mixing D with carbon fiber produced by the vapor phase synthesis method, the utilization rate of CMD is improved and light load discharge is improved. Further, in the positive electrode active material of the present invention, the carbon fiber is coated on the surface of the CMD by mixing the CMD and the carbon fiber, and the carbon material is further molded and pulverized into secondary particles.
Since D is fixed by the carbon fiber network and each of the CMD primary particles is connected to the carbon fiber network, the discharge utilization rate is extremely improved.

[0008]

EXAMPLES Examples of the present invention will be described in detail. Example 1 Chemically synthesized manganese dioxide (CM) obtained by the present invention
D) 60 parts by weight, acetylene black 7.2 parts by weight, 0.8 parts by weight of carbon fibers obtained by the gas phase synthesis method, and 0.6 parts by weight of zinc oxide were mixed well, and an electrolytic solution (ZnCl ₂ 2
49 wt parts of 5 wt% NH ₄ Cl 2.5 wt% aqueous solution) was added and mixed to prepare a uniform positive electrode mixture. An R14 type dry battery was manufactured using this positive electrode mixture.

That is, FIG. 1 shows a bottomed cylindrical zinc can that also serves as a negative electrode. The positive electrode mixture 3 prepared by the above-described method is filled in the zinc can 1 through the separator 2. A carbon rod 4 is inserted in the center of the positive electrode mixture 3. The carbon rod 4 is arranged in the vicinity of the upper portion of the zinc can 1, and is fitted into the through hole of the polyethylene sealing plate 5 for sealing the opening.

On the bottom surface of the zinc can 1, a metal bottom plate 6 also serving as a negative electrode terminal and an insulating ring-shaped thin plate 7 are arranged in an overlapping manner, and these metal bottom plate 6 and ring-shaped thin plate 7 are arranged on the zinc can 1 Are fixed on the outer peripheral surface of the vinyl chloride insulating tube 8 which is heat-shrinked and bent inward.

Further, a metal cap 9 also serving as a positive electrode terminal is fitted on the head of the carbon rod 4. An insulating ring-shaped thin plate 10 is arranged above the peripheral edge of the cap 9, and the ring-shaped thin plate 10 is the insulating tube 8 described above.
It is fixed by bending the upper and lower openings of the metal outer casing 11 laminated inwardly. In the figure, 12 is an insulating bottom plate arranged on the inner bottom surface of the zinc can 1, and 13 is an insulating brim paper arranged on the positive electrode mixture 3.

This dry battery was continuously discharged at 20 ° C. and 2 Ω and 75 Ω continuously, and the discharge duration (final voltage 0.9 V) was measured. As a result, a 2Ω discharge was generated in Figs.
The 5Ω discharge is shown in Table 1.

Example 2 The same type of dry cell as in Example 1 was manufactured and tested, except that 6.4 parts by weight of acetylene black and 1.6 parts by weight of carbon fiber produced by the vapor phase synthesis method were used.

Comparative Example 1 The same type of dry battery as in Example 1 was manufactured and tested, except that 8 parts by weight of acetylene black was used and no carbon fiber was used. The results are shown in FIG. 2 and Table 1. Comparative Example 2 Example 1 was repeated except that the acetylene black was changed to 8 parts by weight and the chemically synthesized manganese dioxide was changed to natural manganese dioxide.
The same type of dry battery as the above was manufactured and tested. Comparative Example 3 The same type of dry battery as in Example 1 was manufactured and tested, except that the chemically synthesized manganese dioxide of Example 1 was changed to natural manganese dioxide.

[0015]

[Table 1]

As is clear from FIG. 2 and Table 1, the manganese dry battery of the present invention is compared with Comparative Example 1 in which carbon fiber is not used,
In the heavy load discharge of FIG. 2, the operating potential is improved, and the discharge duration is also slightly extended accordingly. Furthermore, from the results of 75Ω continuous discharge in Table 1, the batteries of Examples 1 and 2 show excellent discharge performance. Further, the effect is more prominent than the natural manganese dioxide used in Comparative Examples 2 and 3.
Further, as is clear from Table 1, the blending weight ratio of the carbon material produced by the vapor phase synthesis method is preferably 90:10 of acetylene black and the carbon material. As described in detail above, the present invention can provide a manganese dry battery having excellent light load discharge performance.

Further, another embodiment of the present invention will be described in detail. Example 3 1.0 kg of the CMD powder and 10 g of the carbon fiber
(0.99% by weight) was added and mixed well, and 1 kg of water was further added and mixed for 5 minutes. Next, this mixture was dried and then subjected to a roll pressing machine to perform compression molding at a pressure of 3 ton / cm ² , and this molded body was finely crushed to obtain a powder of secondary particles of 100 mesh or less. Using this powder as a positive electrode acting substance, a dry battery was manufactured by the following method. 13.26 g of the positive electrode active substance, to which carbon fiber was added and molded and pulverized, and 2.39 g of acetylene black were well mixed, and 25% by weight of zinc chloride,
Electrolyte solution containing 2.5% by weight of ammonium chloride 1
2.39 g was added to form a uniform positive electrode mixture, and this was used to manufacture an R14 type dry battery.

COMPARATIVE EXAMPLE 4 The following was operated in the same manner as in Example 1, except that the CMD used in Example 3 was not added with carbon fiber and was not crushed by molding.
The same type of dry battery using 3.14 g was manufactured. Comparative Example 5 The same carbon fiber 0.5 was added to 1.0 kg of CMD used in Example 3.
The same type of dry battery was manufactured by using 13.27 g of the positive electrode active substance which was added with g (0.05% by weight) and molded and pulverized. Comparative Example 6 Similarly, 1.01 kg of CMD and 30 g of the same carbon fiber (2.9
1% by weight), and molded and crushed.
The same type of dry battery was manufactured using 53 g. The above Example 3 and Comparative Examples 4, 5, and 6 were continuously discharged at 20 ° C. and 75Ω, and the discharge duration time (end voltage 0.9 V) was measured. The results are shown in Table 2.

[0019]

[Table 2]

[0020]

INDUSTRIAL APPLICABILITY As described above, the manganese dry battery using the positive electrode active material obtained by mixing the CMD of the present invention and the carbon fiber, and the secondary particles obtained by compressing and crushing the positive electrode active material after the mixing. The manganese dry battery used was able to improve the light load discharge characteristics.

[Brief description of drawings]

FIG. 1 is a half sectional view of a manganese dry battery according to the present invention.

FIG. 2 shows 2Ω between an example dry battery of the present invention and a comparative dry battery.
It is a discharge curve figure which compared continuous discharge.

[Explanation of symbols] 1 zinc can 2 separator 3 positive electrode mixture

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kaoru Hobuchi 3-4-10 Minami-Shinagawa, Shinagawa-ku, Tokyo Inside Toshiba Battery Co., Ltd. (72) Nobuaki Chiba 3-4-1-10 Minami-Shinagawa, Shinagawa-ku, Tokyo No. within Toshiba Battery Co., Ltd.

Claims (2)

[Claims] 1. A chemically synthesized manganese dioxide powder produced by roasting natural manganese dioxide, immersing the obtained manganese oxide in a mineral acid solution, washing with water, drying and granulating, and a vapor phase synthesis method. A method for producing a manganese dry battery, which comprises mixing a carbon fiber and using the obtained positive electrode active substance to produce a positive electrode mixture. 2. The method for producing a manganese dry battery according to claim 1, wherein the chemically synthesized manganese dioxide and the carbon fiber are mixed and compression-molded to produce a positive electrode mixture.