JPS59103278A - Alkaline battery - Google Patents

Abstract

PURPOSE:To improve the preservation characteristic of an alkaline battery by preventing any internal short circuits which might be caused during discharge or non-discharge by adding at least one metal selected from among aluminum, gallium, indium and thallium to alkaline electrolyte. CONSTITUTION:0.3wt% of zinc contained in amalgamated zinc powder to be added in the following process of thallium sulfate is dissolved in alkaline electrolyte prepared by dissolving 3wt% of zinc oxide in 35wt% aqueous potassium- hydroxide solution. Next, amalgamated zinc powder and carboxymethylcellulose which is used as a thickener are added to the above electrolyte to prepare amalgamated zinc gel used as a negative electrode. After that, the thus obtained negative electrode and a positive electrode are sealed in a case, thereby constituting an alkaline manganese battery. The same effect can be realized by using aluminum, gallium or indium instead of thallium as the metal added. It is preferred that the quantity of such a metal added be 0.05-0.8% of the quantity of zinc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an alkaline battery using zinc as a negative electrode and an alkaline electrolyte as an electrolyte, and particularly relates to an additive to the alkaline electrolyte.

Conventional Structures and Problems Traditionally, when alkaline batteries, such as alkaline manganese batteries, silver oxide batteries, and mercury batteries, are discharged with a minute current or discharged under an appropriate load for a certain period of time, and then stored, internal short circuits occur. Due to this, the battery's capacity could not be extracted satisfactorily. In order to prevent this phenomenon, in alkaline batteries, it is recommended to use multiple separators or multiple sheets to ensure a distance between the positive and negative electrodes, or to isolate the electrodes with a uniform film such as cellophane. It is taken. In silver oxide batteries and mercury batteries, internal short circuits are prevented by using a uniform film made by graft polymerizing methacrylic acid on polyethylene and stacking cellophane, taking into consideration the oxidizing properties of the positive electrode material.

However, these have problems in that the separator structure is complicated and the material cost is high.

Purpose of the Invention The present invention aims to prevent or alleviate these internal short circuits that occur during battery discharging or when the discharge body is stopped by adding a certain metal to the alkaline electrolyte. 〇Structure of the Invention Aims to Improve the Storage Characteristics of a Battery In order to achieve the above object, the present invention includes adding a trace amount of at least one of the group consisting of aluminum, gallium, insium, and thallium to an alkaline electrolyte. The effect of adding a small amount of this metal to an alkaline electrolyte is not fully understood at present, but Tori et al.'s study showed that metal ions precipitate on the surface of zinc chloride, which is the negative electrode. This is thought to be effective in preventing internal short circuits that occur during microcurrent discharge or after discharge for a certain period of time by changing the properties of zinc oxide.

DESCRIPTION OF THE EMBODIMENTS The present invention will now be described in detail with reference to embodiments showing alkaline manganese batteries. In an alkaline electrolyte in which 3% by weight of zinc oxide is dissolved in a 36% by weight potassium hydroxide aqueous solution, 0.3% by weight of thallium sulfate is dissolved in relation to the zinc in the zinc hydrate powder that will be added in the subsequent process. let Adding frozen zinc powder and carboxymethylcellulose as a thickener to this electrolyte,
Create frozen zinc gel, which is the negative electrode. Separately, as in the conventional case, a cylindrical molded body made of manganese dioxide and graphite is inserted into the positive electrode can to form a positive electrode active material layer. A vinylon nonwoven fabric is wound and inserted in three layers to form a separator layer. The separator is then wetted with an electrolyte and a predetermined amount of the zinc hydrate gel is injected inside it. Thereafter, a negative electrode current collector is inserted into the gel in the conventional manner and the gel is sealed to complete the battery.

This battery is designated as A, and a comparative product using conventional zinc hydrate gel, which is obtained by removing thallium sulfate from the negative electrode composition of A, is designated as B.
The size of both batteries was standardized to R6 type, and the effect of adding thallium was investigated. The internal short circuit occurrence rate when a 30 Ω load was connected to 2 o ○ batteries of both A and B and discharged for 16 hours, and then left at room temperature for 30 days in an open circuit state, and the continuous discharge when a 30 Ω load was connected to 2. The following table shows the incidence of batteries with a capacity of about 60% or less of the theoretical discharge capacity. As is clear from these results, it can be seen that the present invention can produce great effects with extremely simple operations.

Effects of the Invention Although thallium was used as an example in the above embodiment, similar effects were obtained with aluminum, gallium, and indium. The amount of these metals added is 0.06 to 0.0% relative to zinc, expressed as metal weight percent of the compound salt to be dissolved.
．． A range of 8% is good. When the amount added is more than 0.8%, self-discharge proceeds like zinc containing impurities rather than the short-circuit prevention effect obtained, and good results cannot be obtained. On the contrary, O
In amounts smaller than -06%, no significant effect on preventing short circuits was obtained.

In addition, in silver oxide batteries and mercury batteries, sodium hydroxide may be used as an alkali in addition to potassium hydroxide, but even batteries using sodium hydroxide have the same effect as potassium hydroxide. Obtained. In addition, in the examples, thallium was used alone, but aluminum,
The same effect can be obtained with gallium, indium, or a mixture of two or more of these. However, the amount of the mixed additive metal is preferably in the range of 0.05 to 0.8% by weight based on the negative electrode zinc as described above.

Claims (2)

[Claims] (1) An alkaline battery characterized by using an electrolyte solution in which at least one of the group consisting of aluminum, gallium, indium, and thallium is added to an alkaline aqueous solution containing potassium hydroxide or sodium hydroxide as a main component. (2) The alkaline battery according to claim 1, wherein the amount of metal added to the alkaline aqueous solution is 0.06 to 0.8% by weight based on the negative electrode zinc.