JPS58197675A - Alkaline cell - Google Patents

Abstract

PURPOSE:To obtain an alkaline cell having excellent discharge performance of strong consumption current, by employing copolymer of acryl acid soda and itaconic acid soda as the gelation agent for alkali electrolytic. CONSTITUTION:Predetermined amount of uniform mixture of hardened zinc powder having grain size of 80-150 mesh and powder of copolymer of acryl acid soda and itaconic acid soda having average polimerization of 10,000+ or -1,000 and grain size of 100-300 mesh is filled in a metal seal board 1, then alkali electrolyte containing 40wt% of potassium hydroxide and 5wt% of zinc oxide is injected to produce a negative electrode. In such negative electrode, negative electrode mixture powder can be filled in said seal board 1 while being mixed uniformly, while the electrolyte will permeat the alkali electrolyte to the negative electrode powder immediately after injection, to swell gelation and if the addition rate of the gelation agent against the electrolyte is higher than 4.0%, no isolated electrolyte will be left to cause no obstacle against the cell composition.

Description

Detailed Description of the Invention The present invention provides an alkaline manganese battery, a mercury battery, and a silver oxide battery, in which the negative electrode active material is frozen zinc powder, and the electrolyte is an alkaline aqueous solution such as potassium hydroxide, IJium hydroxide, etc. The present invention relates to a negative electrode of an alkaline battery such as a battery, and provides an alkaline battery having excellent discharge characteristics particularly at high current consumption.

Traditionally, alkaline batteries have been manufactured to power consumer devices such as cameras, calculators, electronic watches, and hearing aids.
In recent years, with the rapid diversification and increase in production of these consumer devices, the needs have increased significantly, and depending on the purpose of use,
Different types and sizes of these batteries are used. These characteristics required of batteries as power sources include static characteristics that batteries inherently have such as open circuit voltage and internal resistance, dynamic characteristics such as closed circuit voltage and discharge capacity during use, and long-term characteristics such as leakage resistance. Although they are reliable during storage, with the expansion of battery applications as described above, there is a need for batteries that can provide stable discharge characteristics even at high current consumption, and at the same time have excellent discharge capacity even at low current consumption.

For applications with high current consumption, the battery has a low internal resistance and a battery structure that can draw large currents.For applications with low current consumption, the internal resistance of the battery is slightly high and the discharge characteristics for high current consumption are inferior, but the discharge characteristics for low current consumption are used. They had a battery structure with a large capacity, and were used for different purposes.

There is no problem if batteries of the same size are built into a device for different uses, but when used as a supplementary power source, the appearance is the same, so troubles may occasionally occur where batteries are misused. In addition, in order to prevent such troubles, it was necessary to provide batteries of the same size that have the same battery structure and have excellent discharge characteristics under both strong and weak current consumption.

For this reason, based on the basic requirements in battery design to obtain a high discharge capacity at low current consumption, that is, a structure in which the filling amount of positive and negative electrode active materials, especially the filling amount of the negative electrode, is increased, Furthermore, various attempts have been made to improve the discharge characteristics of large current consumption. For example, the internal resistance of the battery has been reduced by reducing the thickness of the separator and electrolyte-impregnated material disposed between the positive and negative electrodes to reduce the total electrical resistance. However, according to this method, the battery is easily damaged during the assembly process, there are problems with productivity, and there are some problems with reliability during long-term storage. In addition, we used alkali metal salt powder of sodium polyacrylate, which has strong alkali resistance, as a gelling agent for the negative electrode electrolyte, and mixed this uniformly with frozen zinc powder, and injected the alkaline electrolyte to activate the negative electrode. Focusing on the fact that the internal resistance of the battery and the discharge performance of large current consumption are greatly affected by the ratio of sodium polyacrylate to the weight of the electrolyte, we reduced the ratio of sodium polyacrylate to the electrolyte. Therefore, a method of lowering the internal resistance of the battery has been attempted, but even with this method, if the ratio of sodium polyacrylate required for gelling the electrolyte solution is not reached, it is necessary to inject the electrolyte solution and use it as a negative electrode active material. To,
A portion of the electrolyte did not gel, and this free electrolyte leaked during the battery tearing process, creating an obstacle in battery production.

The present invention improves the above-mentioned drawbacks, and uses a copolymer of sodium acrylate and sodium itaconate as a gelling agent for the alkaline electrolyte to produce an alkaline secondary battery with excellent discharge performance at high current consumption. This is what we provide.

That is, as mentioned above, in order to improve discharge performance at large current consumption, it is necessary to reduce the internal resistance of the battery, and one way to do this is to reduce the ratio of gelling agent to electrolyte solution. However, the acrylic copolymer of sodium acrylate and sodium itaconate synthesized so that the average degree of polymerization is within 1ooOo±1000 is necessary for gelling the 40% by weight potassium hydroxide electrolyte shown in Table 1. It can be seen that the larger the ratio of itacon to sodium acid, the lower the ratio, and it is possible to gel the electrolyte with a small amount.

It does not cause any problems in the battery manufacturing process, and the ratio of gelling agent to electrolyte is lowered, resulting in lower internal resistance of the battery.
A, which has excellent discharge performance at high current consumption, is obtained by an aqueous solution polymerization method, and has a particle size of 100 to 300 mes.
h was applied.

An embodiment of the present invention will be described below. The drawing shows a button-type alkaline manganese battery. 1 is a metal sealing plate that also serves as a negative electrode terminal. 2 is a sealing gasket that insulates the positive and negative electrodes and seals the opening. Reference numeral 3 denotes a cylindrical metal case with a bottom, on the inner bottom of which a tablet-shaped mixture 7 of a mixed powder of manganese dioxide and graphite is pressurized and bonded together with a positive electrode ring 8 . 6 is a separator,
5 is an electrolyte-containing lubricant. Reference numeral 4 denotes a negative electrode, which is made of a mixture of frozen zinc powder and powder of a copolymer of sodium acrylate and sodium itaconate as a gelling agent for the alkaline electrolyte, which is impregnated with an alkaline electrolyte. To explain in more detail, the particle size of a copolymer of sodium acrylate and itaconate with an average degree of polymerization of 10000±1000 is added to zinc hydrate powder with a particle size of 80 to 150 mesh.
A metal sealing plate 1 was filled with a certain amount of ~300 mSO powder mixed uniformly in a mill, and an alkaline electrolyte containing 40% by weight of potassium hydroxide and 6% by weight of zinc oxide was injected into this to form a negative electrode. be. The negative electrode constructed in this way can be filled with the negative electrode mixed powder in the metal sealing plate 1 in a uniformly mixed state.Furthermore, after the alkaline electrolyte is injected, the electrolyte immediately penetrates into the negative electrode powder, causing it to swell and gel. Furthermore, if the ratio of the gelling agent added to the electrolytic solution is equal to or higher than the minimum required ratio shown in Table 1, no free electrolytic solution will remain, and this will not cause any trouble to the battery structure.

Table 1 The present invention uses a copolymer of sodium acrylate and sodium itaconate as the gelling agent for the negative electrode, instead of the conventional single polymer of sodium acrylate, as shown in Table 1. It is characterized by the fact that the minimum required amount of gelling agent is small for the electrolyte to gel, and the amount of gelling agent added can be kept low without causing any damage to the battery structure. be.

As described above, a button-type alkaline manganese battery TIS product number LR44 was constructed using the various gelling agents applied and their addition ratios to the weight of the electrolyte shown in Table 2. The weight ratio of sodium itaconate to sodium acrylate in the copolymer of sodium acrylate and sodium itaconate is 5 to 60.
However, if the ratio is less than 5%, the effects shown in Table 1 will not be seen, and if it exceeds 60%, the copolymer may be mixed with frozen zinc powder, or the mixed negative electrode may be placed on a sealing plate. This is because the copolymer powder tends to adhere to the mixing container or the negative electrode filling device when filling the container. However, a range of 10 to 40 inches is optimal. 1 Below Margin Table 2 For these batteries, when discharged at a constant resistance of 3oΩ (7), the ambient temperature is 1.0 volts at 20'C, and the voltage at 0°C is
Table 3 shows the results of measuring the discharge time required to reach 0.8 belt at -20°C. Compared to those using a monopolymer, the discharge performance is improved even at the same weight ratio to the electrolyte.
If the weight ratio of sodium itaconate to sodium acrylate increases, the discharge performance will improve, and if the weight ratio of sodium itaconate to sodium acrylate is high and the addition ratio of the copolymer to the weight of the electrolyte solution is lowered, This shows a significant improvement. Additionally, these batteries were left in an environment with an ambient temperature of 45°C and a relative humidity of 90% to prevent electrolyte leakage.

That is, the liquid leakage resistance was examined, and there were no problems at all after 70 days of storage.

In the example, an electrolyte using potassium hydroxide was explained, but other alkaline electrolytes such as sodium hydroxide have almost the same effect, and silver oxide batteries and mercury batteries other than alkaline manganese batteries Similar effects can be achieved with other alkaline batteries such as

As described above, according to the present invention, the discharge performance at high current consumption can be greatly improved.

[Brief explanation of drawings]

The drawing is a sectional side view of a main part of a button-type alkaline manganese battery according to an embodiment of the present invention. 1... Metal sealing plate, 2... Sealing gasket, 3... Metal canis, 4... Negative electrode, 5... Impregnated material, 6...Separator 1
．． 7... Positive electrode, 8... Positive electrode ring.

Claims (2)

[Claims] (1) An alkaline battery in which an alkaline electrolyte is injected into a mixed negative electrode made by mixing frozen zinc powder with powder of a copolymer of sodium acrylate and sodium itaconate. (2) In the copolymer of sodium acrylate and sodium itaconate, sodium itaconate is 6% of sodium acrylate.
Claim 1 which is a weight proportion of ~5o percent
Alkaline batteries as described in section.