JPS59175563A - Manufacture of manganese dry cell - Google Patents

Abstract

PURPOSE:To provide an excellent discharging characteristic, by using a positive electrode active material made from water-washed or neutralized electrolytic manganese dioxide treated with water solution of alumino salt or the like. CONSTITUTION:Electrolytic manganese washed in water or neutralized with an alkaline solution of sodium or ammonia is mixed and treated with a solution of alumino salt in water or a mixture of aluminum hydroxide and water, and thus the positive electrode active material is provided. As the alumino salt, chloride, nitrate, or sulfate, for example, is usable. As the result, protons, sodium ions, or ammonium ions on the surface of the manganese dioxide are replaced with trivalent aluminum ions, whereby the intersecton of the two straight lines representing the relationship between the potential on the manganese dioxide and the PH value is shifted toward the acidic side and therefore the potential variation per PH is kept low in a wider range of PH values. Thus, the excellent discharging characteristic can be provided, that is, the voltage drop of the cell during its discharging is suppressed and, in particular, the increase in the impedance in and after the middle period of the discharging is made practically negligible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a manganese dry battery using electrolytic manganese dioxide that has been washed or neutralized as a live material after being treated with an aqueous aluminum salt solution or the like.

Manganese drying using manganese dioxide as a positive electrode active material, zinc as a negative electrode active material, and a mixture of zinc chloride and ammonium chloride or an electrolyte mainly containing zinc chloride 1. In the pond, electrolytic manganese dioxide, which has been neutralized using an alkaline aqueous solution and adjusted to a predetermined pH, is used as the positive electrode active material. Acetylene black is added to this manganese dioxide as an electrolyte, and then an electrolyte is added and mixed with stirring to prepare a positive electrode mixture. At this time, a small amount of zinc oxide is added to adjust the battery voltage. The amount of zinc oxide added varies depending on the pH 1 of the electrolytic manganese dioxide used and the required battery voltage, but is usually 1% by weight or less based on the manganese dioxide.

When manganese dioxide electrolytically deposited from a sulfuric acid manganese sulfate bath is washed with water and then treated with, for example, an aqueous solution of caustic soda, aqueous soda carbonate, or an aqueous ammonium hydroxide solution,
As the blocking sulfuric acid is neutralized, protons on the manganese dioxide surface are exchanged with sodium or ammonium ions.

That is, protons are released into the liquid and sodium ions or ammonium ions are adsorbed.

Therefore, the pH of manganese dioxide shifts to a higher level.

When a dry battery is manufactured using such electrolytic manganese dioxide, protons, sodium ions, or ammonium ions on the surface of manganese dioxide are affected by cations in the electrolyte. The degree of influence varies depending on the type and amount of cations adsorbed on manganese dioxide, the type and amount of cations contained in the electrolyte, and the pH of the electrolyte. If the pH of the electrolytic manganese dioxide after neutralization is low, that is, if the amount of exchange between protons in manganese dioxide and cations in the neutralization treatment solution is small, the exchange rate between cations and protons in the decomposition solution after battery rise is low. As a result, protons are released into the electrolyte, the pH of the electrolyte shifts to the acidic side, and the voltage of the battery increases. If the acidity of the @1N solution becomes strong, corrosion of the negative electrode zinc will be promoted if the battery is stored for a long time. If the pH of electrolytic manganese dioxide after neutralization treatment is high,
In other words, if the amount of exchange between manganese dioxide protons and cations in the neutralization treatment solution is large, there will be few protons released into the electrolyte after battery assembly, and the battery voltage will not become so high, but the activity of manganese dioxide will be low. Otherwise, the discharge performance of the battery will deteriorate. The pH of such electrolytic manganese dioxide
In order to reduce the effect on battery voltage due to differences in manganese dioxide, a small amount of zinc oxide is added when formulating the positive electrode mix, but it is difficult to control the amount added according to the pH of manganese dioxide, making it difficult to control battery voltage. However, if the amount added exceeds an appropriate amount, it will adversely affect battery performance, such as a drop in battery voltage during discharge and an increase in impedance. Particularly in the case of discharge from medium load to heavy load, in which heavy load pulse discharge is superimposed, the internal resistance increases significantly from the middle stage of discharge.

The object of the present invention is to eliminate such drawbacks of the conventional technology and particularly to improve the discharge performance of the battery.

When a manganese dry battery is discharged, the voltage of the battery gradually decreases, and most of this is observed on the positive electrode side. Discharge of manganese dioxide at the positive electrode progresses according to the following equation.

10 − Mn02+ H0e = Mn00H − (1) Manganese dioxide is reduced by Mn(I)(c, and H+ is consumed near manganese dioxide, so pl( increases. The generated Mn(III) Mn is eluted by the following disproportionation reaction.

2 Mn0OH+2H-) MnO2+ Mn2++
2H20・= (2) In addition, the lightning position-pH relationship of the manganese dioxide electrode in the electrolyte of a manganese dry battery consists of two straight lines with an intersection, and in the pH region on the acidic side from the intersection, the above (2) is not satisfied. There is Mn2+ produced by the enrichment reaction, and the potential is close to the theoretical potential of -0,118V per pH! , indicating the polar position. In addition, in the pH region on the basic side of the intersection, Mn
Since there is almost no elution of ions, the pE (per -0,
059V] An electrode potential close to that of lightning can be obtained.

As the discharge reaction progresses, the pH increases in the vicinity of manganese dioxide as shown in equations (1) and (2), and elution of 1v1n occurs. If the intersection of 1st position - pH straight ♀ is moved to the acidic side as much as possible, Mn
It is possible to suppress the elution of pHM and to reduce the change in position due to pHM. This can suppress a drop in voltage during discharge of the stain battery, and can prevent an increase in impedance, particularly from the middle stage of discharge.

In the present invention, electrolytic manganese dioxide that has been washed with water or neutralized with an alkaline aqueous solution of sodium or ammonium is treated with an aqueous aluminum salt solution to exchange protons, sodium ions, or ammonium ions on the surface of manganese dioxide with trivalent aluminum ions. In particular, it was found that the potential-pH line intersection of manganese dioxide shifted to the acidic side and showed a low potential change over a wide pH range.

In addition, it was found that the manganese dry battery using this manganese dioxide has a small voltage drop from the middle stage of discharge, and in particular, an increase in impedance shows almost excellent discharge performance.Example After washing electrolytic manganese dioxide with water, N40. Neutralization treatment was performed with an aqueous solution. The pH of this manganese dioxide is JIS K
It was 42 when measured according to 1467.

0.1 M)d for 10 parts by weight of this manganese dioxide
cll and 50 parts by weight of the solution were shaken at room temperature for 2 hours. After shaking, the supernatant was collected, washed 5 times with water, and dried for P weeks. Using this manganese dioxide, a zinc chloride type manganese dry cell SILM-3 was constructed as a battery (A) according to the present invention. Using electrolytic manganese dioxide that has only been neutralized without MCl3 solution treatment, 0.8% by weight of zinc oxide is added to the manganese dioxide, and the rest is battery (
Same as A) but 8uM-3.
). The battery discharge and test results are shown in the drawing. The change in terminal voltage when the cell (A) of the present invention'b was continuously discharged with a load resistance of 1.2 Ω is shown as A, and the change in impedance (internal battery resistance) is shown as ■. In addition, during the 1 and 2 KO continuous discharges, a pulse discharge of 1 N for 5 Ω impression seconds was superimposed, and the change in terminal tube pressure at that time is shown as A. A similar test was conducted on the same conventional battery (B), and B and ■
, shown as B. As is clear from the drawings, in the battery of the present invention, the drop of the terminal type 5 battery from the middle stage of discharge is small, and there is hardly any increase in impedance from the middle stage of discharge.

Further, it can be seen that the voltage drop when a 5Ω pulse discharge is superimposed is extremely small compared to the conventional 'Ffjfbh. As described above, the battery of the present invention can obtain extremely superior discharge characteristics compared to conventional batteries. An example of a medium load discharge of 1.2Ω discharge was shown for an SqM-3 battery, but the battery of the present invention has superior discharge performance compared to conventional batteries even under heavy load lightning strikes with low load resistance. It was found that

In addition, although the embodiment of the present invention uses an aqueous aluminum salt solution, the same effect can be obtained by mixing aluminum hydroxide and water, or using aluminum nitrate or sulfate. It can also be used.

[Brief explanation of the drawing]

The figure is a comparison diagram of the discharge curve and impedance curve of the battery of the present invention and a conventional battery. A, A... Discharge curve of the battery according to the present invention ■〃 Impedance B, B... Discharge curve of the conventional battery ■... Name of the impedance patent applicant

Claims (2)

[Claims] (1) Electrolytic manganese dioxide that has been washed with water or neutralized with an alkaline aqueous solution of sodium or ammonia,
A method for manufacturing a manganese dry battery, which comprises mixing an aluminum salt aqueous solution or an aluminum hydroxide with water and treating the mixture for use as a positive electrode active material. (2) The method for producing a manganese dry battery according to claim 1, wherein the aluminum salt is a chloride, nitrate, or sulfate.