JPS5857866B2 - Zinc cathode for alkaline batteries - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an East Lead cathode for an alkaline primary battery, and more particularly to a zinc cathode which has excellent heavy load discharge characteristics, discharge performance at low temperatures, and storage performance, and which is easy to manufacture.

The so-called zinc-alkaline battery uses metal zinc as the cathode active material and an alkaline electrolyte such as caustic potash or caustic soda, and uses silver oxide, manganese dioxide, air, nickel oxide, etc. as the anode active material, and has not been widely put into practical use. has been done.

Although it is theoretically possible that this type of battery has excellent high-load characteristics, can operate at low temperatures, and has a large initial capacity despite its relatively simple structure, in reality, sufficient performance has not yet been achieved.
Many improvements have been made.

That is, it is widely known that the discharge performance and shelf life can be improved by using fine particles such as powder or fibers as zinc or by increasing the mercury content of the lead powder.

In addition, silicate ions are used to maintain shelf life and increase initial capacity by preventing the elution of zincate ions into the negative electrode and electrolyte by dispersing zinc powder in a gel-like electrolyte. However, this method has the disadvantage that it is not necessarily effective in terms of heavy load characteristics or low temperature characteristics.

There are also examples of adding magnesium oxide to the electrolyte.
This is said to be effective in preventing silver ions leaching from the positive electrode due to discharge of a silver-zinc oxide battery.

On the other hand, the blank-type lead cathode used as the negative electrode of alkaline batteries is made of fine zinc powder, a binder, and inorganic substances that are insoluble even when they come into contact with zinc in an alkaline electrolyte, such as calcium, magnesium, aluminum, silicon, barium, and titanium. Add oxide, fluoride, and carbonate powder and stir well with water 1↑
Some products are formed by mixing, drying, and then press molding.
It is said to improve heavy load characteristics and low temperature characteristics.

In this case, the fine zinc powder and binder are in a solidified state due to pressure molding, so it may take a very long time for the high concentration alkaline electrolyte to penetrate into the electrode body, or the penetration of the solution may be slow. It had the disadvantage that it did not always produce the expected performance because some parts were not perfect.

In addition, it is not always sufficient to uniformly disperse zinc fine powder, which is an inorganic particle to be added and mixed, due to solid boundary tension, and it is difficult to mold a negative electrode body with uniform performance in a short time. If the dispersion is non-uniform, the capacity of small batteries will vary greatly, and a sufficient effect will not be obtained in terms of capacity after storage.

The present invention was made in view of the above-mentioned problems, and provides an alkaline primary battery that has excellent heavy load characteristics and low-temperature discharge performance, has an exceptional initial capacity, has a long shelf life, and is easy to manufacture. The purpose is to provide a useful lead cathode.

The gist of the present invention is as follows.

That is, metallic zinc powder is used as the negative electrode active material, to which zinc oxide or zinc hydroxide is added, and titanium,
One or more powders of oxides or hydroxides of magnesium or zirconium dioxide and a gelling agent such as an alkali-resistant carboxy polymer polymer such as carboxy vinyl polymer, sodium polyacrylate, or carboxy ether polymer. After adding and mixing uniformly, an alkaline electrolyte such as caustic potash or caustic soda is added thereto and stirred to obtain a gel-like negative electrode active material, which is used as a cathode of an alkaline battery.

As the metal lead powder, mercury amalgamated zinc powder can usually be used.

In addition, as another attempt, polystyrene or other alkali-resistant binders such as polyethylene, tetrafluoroethylene, etc., dissolved in an organic solvent such as l-2 dichloroethane, benzene, acetone, etc., were used without adding an alkaline electrolyte to the above composition. The desired effect can be obtained even when a cathode body formed by adding and mixing materials such as the above and molded into a shape convenient for assembly and handling is used.

As a result of various studies on the effects of the zinc cathode of the present invention, we have found that zinc oxide or lead hydroxide powder is made to coexist with zinc fine particles, and after mixing each solid powder, a sufficient amount of alkaline electrolyte is used. The gel-like mixture obtained by stirring and mixing was found to be an extremely effective cathode mixture.

It was found that this is due to the fact that zinc oxide or zinc hydroxide powder is compatible not only with metallic zinc powder but also with mixed oxides such as magnesia, titania, and zirconia, and has the role of increasing compatibility between the two. .

It is also desirable to dissolve an appropriate amount of zinc oxide in the alkaline electrolyte used beforehand.

It has been found that when this alkaline electrolyte is immediately used to form a gel, a sufficient amount of the electrolyte uniformly permeates between magnesia titania and the like due to the partial dissolution of zinc oxide and is absorbed.

Due to this effect, a sufficiently large amount of electrolyte is always present around the zinc fine particles, the polarization is small during heavy load discharge, the reaction surface is sharpened, and the discharge performance at low temperatures is improved.

It has also been found that the above oxides have poor surface conductivity in an alkaline electrolyte.

As a result of these surrounding the zinc fine particles, the enlargement of the particles and the deformation of the electrode, which would otherwise occur due to direct contact between the zinc particles, do not occur.

In this way, the East Lead cathode of the present invention has heavy load characteristics, low temperature characteristics,
In addition to having excellent retention properties, it does not cause deformation of the zinc cathode, and when injecting electrolyte into the cathode during the manufacturing process, the injection time is shortened, and sufficient electrolyte is maintained uniformly. It has the effect of being

Furthermore, since magnesia, titania, etc. have the property of adsorbing Azuma lead ions dissolved in the alkaline electrolyte, the concentration of Azuma lead ions contained in the electrolyte decreases, and the zinc fine particles that are the cathode active material dissolve. However, by injecting zinc oxide or hydroxide, it dissolves in the electrolyte instead of the Azuma lead fine particles and replenishes the reduced amount, so a high battery capacity can be maintained over a long period of time. It turns out.

On the other hand, when used for a long period of time, the electrodes may be deformed or damaged due to physical factors such as vibration and shock due to various environments including usage conditions, and the electrodes may become connected to current collectors such as wire mesh. Fluororesin, polyethylene, polystyrene, etc. are used as substances that provide favorable results by preventing poor electrical contact with other substances, increasing electrical resistance and lowering the utilization rate, and increasing polarization during operation. It has been revealed that there is a binder made of high molecular weight compounds.

The present invention will be described below with reference to embodiments thereof.

Example 1 Composition 10% mercury amalgamated zinc powder 93°5 parts (
(passed through 100 meshes) (weight) Zinc oxide powder 2 Magnesium oxide powder 3 Carboxy vinyl polymer powder 1.5 10% mercury amalgamation unresolved 93.5 parts (1
(passed through 100 meshes) (weight) Example composition Pre-oxidized lead powder 2 Titanium oxide powder 3 Carboxy vinyl polymer powder 1°5 Example 3 Composition 10% water-grained amalgamated lead powder 93° 5 parts (passed through 100 meshes) (weight) ) Pre-oxidized lead powder 2 Zirconium oxide powder 3 Carboxyvinyl polymer powder 1゜5 Example 4 Set e, 10% mercury amalgamated East Lead powder 93゜5
parts (passed through 100 meshes) (weight) Hydroxylated lead powder 2 Magnesium oxide 3 carboxyvinyl polymer powder 1°5 Example 5 Composition io% mercury amalgamated zinc powder 93°5 parts (passed through 100 meshes) (weight) Oxidation range Lead powder 2 Magnesium hydroxide powder 3 Carboxy vinyl polymer → 9$ 1.56
*Example* Composition 10% mercury amalgam lead powder 93゜5
parts (passed through 100 meshes) (weight) Lead powder before oxidation 2 Magnesium oxide powder 2 Zirconium oxide powder 1 Carboxy vinyl polymer powder 1°5 or more Example 1
゜Each composition of 2, 3, 4, 5, and 6 was thoroughly stirred and mixed using a glass V-mixer over 30 minutes or more, and 100 parts of these mixed powders were added with 35% KOH containing 5% lead oxide. 70 parts of the aqueous solution was added and stirred uniformly and well in a nitrogen gas atmosphere to obtain a gelled lead negative electrode dispersion.

This was used as a negative electrode mixture, and the positive electrode contained 95 parts of mercury oxide and 4 parts of graphite.
2 t or Jcr?
Using the t-molded product, an H-C type battery was assembled with a nylon nonwoven fabric separator interposed therebetween.

In contrast, the conventional product used lead oxide powder as its composition and was assembled using the same method.

These batteries were continuously discharged at 25°C and 0°C using a 5,000 resistance resistor, and the discharge duration was measured when the final voltage was 009V.The results are summarized in the table below. Compared to the conventional product, the button duration for each embodiment is longer, and the average operating voltage for each embodiment is 1°23V at 25°G, whereas the conventional product is 1°.

The effect of reducing polarization during operation at 205 V and discharge duration became clear.

Furthermore, while the ratio of the discharge duration at 0° C. to the discharge duration at 25° C. is approximately 50% in the conventional product, this has been improved to approximately 60% in each of the Examples.

On the other hand, when the characteristics of the same battery after storage were examined under the above-mentioned conditions of 25°C, the results shown in Table 2 were obtained, indicating that the battery according to the present invention is extremely effective.

Claims (1)

[Claims] 1 Adding zinc oxide or zinc hydroxide powder, one or more powders of oxides or hydroxides of Mg, Ti, and Zr, and gelling agent powder stable in an alkaline electrolyte to metal zinc powder. A zinc cathode for an alkaline primary battery, characterized in that it consists of a mixture of: