JPS58145061A - Alkaline manganese cell - Google Patents

Abstract

PURPOSE:An alkaline manganese cell, in which a large amount of alkaline electrolyte is held to improve a cell characteristic by modifying a positive electrode compound with a mixture of electrolytic manganese dioxide, manganese dioxide hydrate and carbonaceous conductive agent. CONSTITUTION:A mixture obtained by stirring to mix electrolytic manganese dioxide, manganese dioxide hydrate and carbonaceous conductive agent or the like is used to modify a positive electrode compound in an alkaline manganese cell. A quantity of manganese dioxide hydrate in this mixture is arranged about 5-20% the total quantity of manganese dioxide. This positive electrode compound, being not mixed with an alkaline electrolyte, never absorbs carbonic gas in the air and can prevent increase of internal resistance and deterioration of a low temperature characteristic of the cell. Further existence of manganese dioxide hydrate can hold a large amount of alkaline electrolyte, and the low temperature characteristic and rapid discharge characteristic can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an alkaline manganese battery with an improved positive electrode mixture.

Recently, this type of alkaline manganese battery has become smaller.

High-performance batteries tend to be used in many applications such as calculators and camera strobes.

Incidentally, it is known that in such a battery, the positive electrode mixture has a great influence on the battery characteristics.

Therefore, the conventional method for obtaining a positive electrode mixture is to mix al-manganese dioxide and a carbonaceous conductive agent such as phosphorous graphite, and then add an organic solvent solution of a synthetic polymer resin such as polystyrene as a binder and knead the mixture. This is followed by heating and drying while stirring to obtain a positive electrode mixture.

[b) A method of mixing manganese dioxide and a carbonaceous conductive agent such as phosphorous graphite, adding water to form a thriller, and then spraying and granulating and drying to obtain a positive electrode mixture.

(C) A method in which manganese dioxide and a carbonaceous conductive agent such as phosphorous graphite are mixed, then an alkaline electrolyte is added and kneaded, and then dried to a predetermined moisture content using, for example, a fluidized bed heating dryer to obtain a positive electrode mixture. .

etc. are used.

However, according to method (a), since the alkaline electrolyte is not mixed, carbon gas in the air is not absorbed and the mixture is easy to work with and has a uniform filling amount. It is difficult for the alkaline electrolyte to penetrate into the mixture, and the amount of electrolyte retained in the mixture is small. For this reason, the discharge reaction area is small, the operating voltage during discharge is low, and the shortcomings are that the rapid discharge characteristics and low-temperature characteristics are particularly deteriorated.

In addition, method (b) does not mix alkaline electrolyte, so it does not absorb carbon dioxide gas in the air, has good workability, and provides a mixture with a uniform filling amount. However, it is possible to improve the penetration of the alkaline electrolyte into the positive electrode mixture.

Again, if the amount is too large, it is difficult to penetrate the alkaline electrolyte, which has the disadvantage of deteriorating the characteristics as in (a).

Furthermore, according to the method of fc), the penetration of alkaline electrolyte is (
a) It is better than (b), but since an alkaline electrolyte is added, carbon dioxide gas in the air is absorbed during heating and drying, and this carbon dioxide gas may increase the internal resistance of the battery or damage the negative electrode active material. This has the disadvantage that it promotes passivation of zinc, which deteriorates the low temperature characteristics and rapid discharge characteristics of the battery.

The purpose of this invention is to provide an alkaline manganese battery that can hold a large amount of alkaline electrolyte in the positive electrode mixture by improving the positive electrode mixture, and can improve battery characteristics including rapid discharge characteristics and low temperature characteristics. do.

An embodiment of this invention will be described below.

First, to describe the general structure of the alkaline manganese battery obtained by the present invention, in Drawing I, 1 is a positive electrode container which also serves as a positive electrode terminal, and this positive electrode container 1 is filled with a positive electrode mixture under pressure, and a positive electrode 2 is placed therein. It has gained.

A gelled negative electrode agent 4 is housed inside the positive electrode 2 with a nonwoven fabric separator 3 interposed therebetween. 5 is an insulating backing made of synthetic resin, and 6 is a sealing plate that also serves as a negative terminal.

7 is a current collector rod, 8 is an insulating bottom plate, 9 is an opening of the positive electrode container, and the sealing plate 6 is bent inward through the insulating backing 5 to seal the opening, and 1 is a cylindrical alkali. Consists of manganese dry batteries.

In this case, in the alkaline manganese battery constructed as described above, the positive electrode mixture is obtained as follows.

(1) Embodiment ■ A positive electrode mixture was prepared from a mixture obtained by stirring and mixing electrolytic manganese dioxide, hydrous manganese dioxide, and a carbonaceous conductive agent.

Here, hydrated manganese dioxide is produced by reducing an alkaline permanganese potassium solution with an aqueous reducing agent solution, and is precipitated.
Alternatively, an acid is added to an alkaline potassium manganese (Vl) solution to form a precipitate by a disproportionation reaction.The typical composition of the hydrated manganese dioxide prepared by this method after drying at 105°C for 2 hours is as follows: Content of MnO, about 65~
'zol is expressed as a 0 content of about 14 to 18% and a content of about 13 to 18% when the rest is considered as bound water.

Expressing this in terms of molar ratio, it is approximately [K, 0.4Mn02.4
It has a composition of H, 0), is amorphous in terms of Xa, and has an extremely large BET surface area of about 120 to 160 m/g. In addition, such hydrated manganese dioxide is a fine particle and has a small apparent density, so if it is added in excess of 20% of the total manganese dioxide amount, the apparent density of the positive electrode mixture will become small and the total manganese dioxide weight per battery will become too small. Also, if the amount is less than 5%, the effect of addition cannot be expected, so it is set in the range of 5% to 20%.

In this way, since no alkaline electrolyte is mixed, carbon dioxide gas in the air is not absorbed, and the battery's internal resistance and low-temperature characteristics, which are caused by absorption of carbon dioxide gas, are reduced.
Deterioration of sudden discharge characteristics can be prevented. In addition, hydrated manganese dioxide itself contains a large amount of alkaline components and bound water, so when injecting alkaline electrolyte after filling the positive electrode mixture into the positive electrode container, a large amount of electrolyte can be secured even with a small amount of electrolyte. Manganese dioxide is a fine powder with a low apparent density, so it can be injected with good workability even if the amount of alkaline electrolyte is increased.

As a result, a large amount of alkaline electrolyte can be held, so a large discharge reaction area can be obtained, and low-temperature characteristics and rapid discharge characteristics can be significantly improved.

(2) Embodiment ■ A positive electrode mixture was prepared by heating and drying a mixture obtained by stirring and mixing electrolytic manganese dioxide, hydrous manganese dioxide, and a carbonaceous conductive agent.

゛ How can we expect the same effect as Embodiment I?Even if it is heated and dried to 1%, since no alkaline electrolyte is mixed, there is no absorption of carbon dioxide gas in the air, an increase in battery internal resistance, and low-temperature characteristics. and there is no deterioration in rapid discharge characteristics.

(3) Embodiment ■ Hydrous manganese dioxide has a small apparent density, so Embodiment I
Alternatively, a synthetic water-soluble polymer was added as a binder to the mixture of electrolytic manganese dioxide, hydrated manganese dioxide, and carbonaceous conductive agent described in (2) to prepare a positive electrode mixture.

If this is done, the effects of embodiments I and H can be expected,
In addition, a binder (due to its binding effect, it can prevent the positive electrode mixture from loosening and hold a large amount of alkaline electrolyte.

Now, as a specific example, the present invention is applied to an alkaline manganese battery LH, 6 (outer diameter 14.0 mm, height 49.8 rrm).
) A comparison was made between the case where this was applied and the conventional product in terms of the following items.

In this case, the product of the present invention contains 66 parts of electrolytic manganese dioxide, and 66 parts of hydrated manganese dioxide (0.
300% of a mixture of 1M KMnO and 0.2M KOH
While stirring for 1 hour, 3 g of H,0, was added to form a precipitate, which was held for 30 minutes, followed by over-washing, and further dried at 105°C. The composition at this time is Mn0゜67.5%, K, 017.1
3%, bound water 14.71 theal. ) 6.5 parts, 10 parts of phosphorous graphite, 17 parts of SG1.10KoH, and 0.5 parts of synthetic water-soluble polymer (crosslinked sodium polyacrylate)
The water content is 514 and 8
(A positive electrode mixture was prepared by drying at 72.5 parts of manganese, 10 parts of phosphorous graphite, SG1.10
A positive electrode mixture with a water content of 5 cm was prepared in the same manner as above by stirring and mixing 17.5 parts of KOH, and a predetermined amount of this was filled into a positive electrode container, and after adding an alkaline electrolyte, the negative electrode container was fitted on both sides to complete the battery. Assembled.

'First, with a load resistance of 5Ω, a pulse discharge of 5 second discharge, 5 second pause was performed, and the duration until the final voltage reached 0.9 Vl was investigated, and the results shown in Table 1 were obtained. The measurement temperature in this case was 25°C and -20°C, and the average value of 9 test pieces was shown. Further, A is a product of the present invention, and B is a conventional product.

Table 1 According to this table, it was found that the battery obtained according to the present invention had good rapid discharge characteristics and low temperature characteristics.

Next, the inventive product and the conventional product were tested at 20°C with a load resistance of 100, θ
The results shown in Table 2 were obtained by examining the duration of continuous discharge up to a final voltage of 0.9 V at temperatures of -20°C and -20°C. In this case, Table 2 shows the average value of 9 test pieces.

Table 2 According to this table, it was found that the battery obtained from this invention had good discharge characteristics.

As described above, according to the present invention, by improving the positive electrode mixture, an alkaline manganese battery that can retain a large amount of alkaline electrolyte in the positive electrode mixture and improve battery characteristics including rapid discharge characteristics and low temperature characteristics can be obtained. can be provided.

[Brief explanation of the drawing]

The drawing schematically shows the structure of the battery obtained according to the present invention.

Claims (4)

[Claims] (1) An alkaline manganese battery characterized by using a positive electrode mixture consisting of a mixture of electrolytic manganese dioxide, hydrous manganese dioxide, and a carbonaceous conductive agent. (2) The alkaline manganese battery according to claim 1, wherein the mixture is dry. (3) The alkaline manganese battery according to claim 1 or 2, wherein the mixture has a synthetic water-soluble polymer as binder L. (4) The alkaline manganese battery according to claim 1 or 3, wherein the amount of hydrated manganese dioxide in the mixture is 5 to 20% of the total amount of manganese dioxide.