JPH06231757A - Zinc alkaline battery - Google Patents

Abstract

PURPOSE:To reduce an internal resistance of a battery so as to provide a good discharge characteristic by adding calcium hydroxide or calcium oxide into a gel zinc negative electrode. CONSTITUTION:Calcium hydroxide or calcium oxide is added in a gel zinc negative electrode 5 so as to increase electron conductivity in zinc hydroxide or zinc oxide, which are a discharge reaction products from zinc. An addition amount rate of calcium hydroxide to zinc is 0.005-0.1% in terms of calcium hydroxide. As a result, an internal resistance of a battery can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc-alkaline battery using zinc as a negative electrode active material, an alkaline aqueous solution as an electrolyte, and manganese dioxide, silver oxide or the like as a positive electrode active material, and more particularly to improving discharge performance.

[0002]

2. Description of the Related Art Conventionally, a method of adding mercury to zinc has been industrially adopted in order to suppress corrosion of zinc in an alkaline electrolyte. However, in recent years, social concern over environmental pollution of mercury in waste batteries has increased, and alkaline batteries that do not contain mercury have been industrialized. This mercury increases hydrogen overvoltage and suppresses corrosion of zinc.
By interposing between zinc alloy powders, it serves to mediately enhance the electron conductivity between zinc alloy powders, but without mercury addition, the electron conductivity deteriorates and the discharge performance deteriorates as the internal resistance of the battery increases. To do. As a means to supplement this,
Conventionally, carbon and / or graphite powder (JP-A-61-58)
No. 165) or a conductive agent such as metal powder (Japanese Patent Laid-Open No. Sho 6-62).
1-96665) is added to a gel zinc negative electrode.

[0003]

In the zinc alloy powder dispersed in the alkaline electrolyte in the form of gel, the surface of zinc is not oxidized by the discharge reaction at the initial stage of the discharge reaction, and the electrons generated by the discharge reaction are easy. It can move to the negative electrode and the collector. However, as the discharge reaction proceeds, zinc hydroxide oxide and zinc oxide, which are discharge products, are deposited on the zinc surface, and the electrical continuity between the zinc powder particles and between the zinc powder and the current collector deteriorates. If mercury is not added, the electrical continuity is further deteriorated and the discharge performance is deteriorated. In order to solve the above-mentioned problems, as an alternative to the function of mercury as an electron conducting medium, carbon and / or graphite powder (JP-A-61-58165) or a conductive agent such as metal powder (JP-A-61-58165). (Sho 61-96665)
There has been proposed a technique of adding the above to a gel zinc negative electrode.
However, the present invention focuses on enhancing the electronic conductivity of the discharge product of zinc, reduces the internal resistance of the battery and has excellent discharge characteristics without adding a conductive agent as proposed above. An object is to provide a zinc-alkali battery containing no mercury.

[0004]

In order to reduce the internal resistance of the battery during discharge, the zinc-alkaline battery of the present invention uses calcium hydroxide and / or calcium oxide as a conductive additive in the form of calcium hydroxide with respect to zinc. 0.0
It is characterized in that 05 to 0.1% was added to the gelled zinc negative electrode.

[0005]

[Function] Calcium hydroxide and /
Alternatively, by adding calcium oxide, it becomes possible to reduce the internal resistance of the battery by increasing the electronic conductivity of zinc hydroxide or zinc oxide, which is the discharge reaction product of zinc, and as a result, the discharge performance of the battery. Is improved. Although its action and effect have not been fully clarified, it is presumed as follows. The discharge reaction of zinc proceeds according to the following equation.

[0006]

[Chemical 1]

When the zinc acid complex ions generated here are discharged and the concentration increases on the zinc surface (Chemical formula 2), zinc hydroxide or zinc oxide is generated on the zinc surface as shown in (Chemical formula 3). It is deposited as a passivation film.

[0008]

[Chemical 2]

[0009]

[Chemical 3]

On the other hand, in strong alkaline electrolytes used in zinc-alkaline batteries, when calcium, which is stable in the state of calcium hydroxide, is present in the gel zinc negative electrode, the zinc acid complex ions form zinc hydroxide or zinc oxide. When it becomes, it is thought that it forms a composite hydroxide of zinc and calcium while taking in calcium hydroxide, suppresses the formation of the above-mentioned passivation film, facilitates the discharge reaction, and enhances the electron conductivity. To be

[0011]

EXAMPLES The effects of the present invention will be described below with reference to examples. (FIG. 1) is an alkaline battery LR6 used in this example.
3 is a structural cross-sectional view of FIG. In FIG. 1, 1 is a label exterior, 2 is a positive electrode case, 3 is a positive electrode mixture, 4 is a separator, 5 is a gel negative electrode, 6 is a current collector, 7 is a resin sealing body, 8 is an insulating washer, and 9 is Insulating resin 10 is a bottom plate.

First, in order to investigate the effect of the present invention, the effect on the discharge performance was examined with respect to the amount of calcium hydroxide added to the gel zinc negative electrode. That is, zinc alloy powder 66 Wt%, gelling agent 1 Wt%, alkali concentration 38
% Alkaline electrolyte solution 33 Wt% and calcium hydroxide were mixed in the amounts shown in (Table 1) to prepare a gelled zinc negative electrode.

[0013]

[Table 1]

Using this gel zinc negative electrode, an AA alkaline battery was manufactured, the discharge duration of 10 Ω1 hour / day and the internal resistance of the battery during discharge were measured, and the results are shown in (Table 1). . As is clear from (Table 1), the addition of 0.005% or more of calcium hydroxide to zinc suppresses an increase in the internal resistance of the battery at the end of discharge and improves the discharge performance.

In addition, the discharge duration of 3.9Ω for 5 minutes / day was also measured, and the results are shown in (Table 2).

[0016]

[Table 2]

As is clear from (Table 2), when the amount of calcium hydroxide added is 0.1% or more with respect to zinc, a dendrite of good conductivity is generated in the separator and a short circuit occurs inside the battery. , The discharge performance deteriorated.

Further, the alkaline dry battery produced here was stored at 60 ° C. for one month, and the occurrence of leakage was examined. The results are shown in (Table 2). As shown in (Table 2), no liquid leakage phenomenon due to addition of calcium hydroxide is observed, and high liquid leakage resistance can be obtained.

As described above, according to this embodiment, by using the gelled zinc negative electrode to which calcium hydroxide was added in the range of 0.005 to 0.1% with respect to zinc, excellent discharge performance was obtained. A zinc alkaline battery can be provided.

[0020]

As described above, the battery using the gelled zinc negative electrode of the present invention does not contain mercury, and has a longer discharge duration when connected to a load than that of a conventional battery, and is excellent in leakage resistance. Battery can be provided.

Although calcium hydroxide was used in the examples, calcium is stable as calcium hydroxide in the strong alkaline electrolyte used in alkaline batteries. Therefore, when calcium hydroxide is added to gel zinc, calcium oxide is used. Alternatively, even if calcium was added, almost the same result was obtained because it changed to calcium hydroxide. Similar results were obtained for other types of batteries such as button type alkaline manganese batteries and silver oxide batteries.

[Brief description of drawings]

FIG. 1 is an alkaline dry battery LR6 according to an embodiment of the present invention.
FIG.

[Explanation of symbols]

 3 Positive electrode mixture 4 Separator 5 Gel negative electrode

Claims (2)

[Claims] 1. An alkaline battery provided with a gelled zinc negative electrode in which a mercury-free zinc alloy powder is dispersed in a gelled state in an alkaline electrolyte as a main active material of the negative electrode. A zinc alkaline battery containing calcium and / or calcium oxide. 2. The zinc alkaline battery according to claim 1, wherein the amount of calcium hydroxide added is 0.005 to 0.1% as calcium hydroxide relative to zinc.