JP2001006680A - Zinc alkaline battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-pollution zinc alkaline battery using non- amalgamated zinc alloy powder in a gel-form zinc negative electrode equipped with an enhanced easy-to-fill property of negative electrode, anti-shock characteristic of battery, and discharging performance. SOLUTION: An agent to turn into gel contained in a gel-form zinc negative electrode 4 of a zinc alkaline battery is prepared from bridged polyacrylate whose 0.5-wt.% water solution dispersed viscosity at 25 deg.C is 10,000-20,000 cPs and particle sizes range chiefly between 100-500 μm and chain-form polyacrylic acids or its salt whose 0.5-wt.% water solution dispersed viscosity at 25 deg.C is 3,000-12,000 cPs and particle sizes range chiefly below 100 μm. This allows heightening of the lubricating performance while a necessary viscosity for the anti-shock property of the battery is well maintained, and anti-shock property and the working easiness can be enhanced compatibly.

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, and more particularly, to a zinc-alkaline battery provided with a gelled zinc negative electrode using a non-melted zinc alloy powder.

[0002]

2. Description of the Related Art Conventionally, as a negative electrode active material for a zinc alkaline battery, a zinc alloy powder of mercurized zinc alloy has been used for the purpose of suppressing gas generation due to corrosion of zinc and improving electric characteristics. Environmental pollution caused by batteries has become a problem, and low pollution has become a social demand. Zinc alloy compositions and anticorrosives (inhibitors) to eliminate zinc alloy powder from mercury-free (mercury-free) Research has been progressed, and finally a gelled zinc negative electrode for a mercury-free alkaline battery having practically no problem in gas generation has been developed.

[0003] By the way, it was found that a battery using only a non-melonized zinc alloy powder had lower impact resistance than a battery using a non-melted zinc alloy powder. Therefore, measures have been taken to improve the impact resistance by increasing the viscosity of the gelled zinc negative electrode by reviewing the shape and particle size of the gelling agent or increasing the amount of the gelling agent.

However, when the viscosity of the gelled zinc negative electrode is increased in order to improve the impact resistance of the battery, the friction between the gelled zinc negative electrode and the wall of the filling device when filling the battery with the gelled zinc negative electrode increases, and the gelled zinc negative electrode becomes smoother. Since the gelled zinc negative electrode does not flow, it is difficult to perform a stable filling operation. Therefore, it has been practiced to add a fluorine-based surfactant to a gelled zinc negative electrode to facilitate the filling operation.

[0005]

However, it has been found that the addition of such a fluorine-containing surfactant acts as an internal resistance of the battery, thus causing a problem of shortening the discharge duration.

The present invention has been made in view of the above circumstances, and has as its object to provide a low-pollution zinc-alkali battery using a non-melting zinc alloy powder for the gelled zinc negative electrode. The present invention is to facilitate the filling of the resin, improve the safety by maintaining good impact resistance, and enhance the discharge performance.

[0007]

That is, the present invention relates to a zinc-alkaline battery having a gelled zinc negative electrode containing a non-melonized zinc alloy powder, a gelling agent and an alkaline electrolyte. A crosslinked polyacrylate having a 0.5% by weight aqueous dispersion viscosity of 10,000 to 20,000 cps and a particle size of mainly 100 to 500 μm, and a 0.5% by weight aqueous dispersion dispersion viscosity at 25 ° C. Is used in combination with a linear polyacrylic acid or a salt thereof having a particle size of 3,000 to 12,000 cps and a particle diameter of 100 μm or less.

In the present invention, the gelled zinc negative electrode is prepared by using the above two kinds of gelling agents in combination, so that the viscosity of the gelled zinc negative electrode can be increased to such an extent that the impact resistance of the battery can be maintained. It is possible to provide a zinc-alkali battery having lubricating properties and facilitating the filling of the gelled zinc negative electrode into the battery. As a result, both the impact resistance and the discharge performance of the battery are excellent, and the workability is also improved. it can. The amount of the two gelling agents used is such that the concentration of the crosslinked polyacrylic acid salt is 2.0 to 3.5% by weight based on the alkaline electrolyte, and the concentration of the chain polyacrylic acid or salts thereof. Is preferably in the range of 0.05 to 0.5% by weight based on the alkaline electrolyte.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention and comparative examples will be described in detail. First, a gelling agent A and a gelling agent B are added to 100 g of an electrolytic solution composed of an aqueous solution of potassium hydroxide and zinc oxide, and a non-melonized zinc alloy powder is further added to prepare a 300 g gelled zinc negative electrode. did. Gelling agent A has a 0.5% aqueous dispersion viscosity at 25 ° C. of 15,000 cps and a particle size of 100 to 50.
It is a crosslinked polyacrylate salt having an average particle diameter of 300 μm mainly composed of 0 μm.
It is a linear polyacrylic acid having a 5% aqueous dispersion viscosity of 9,000 cps, a particle size of 100 μm or less, and an average particle size of 10 μm. The amounts of these gelling agents (% by weight based on the amount of the electrolyte) are as shown in Table 1. Using the gelled zinc negative electrode thus prepared, JI shown in FIG.
An S standard LR6 (AA) alkaline battery was assembled.

In FIG. 1, reference numeral 1 denotes a bottomed cylindrical metal can also serving as a positive electrode terminal. In the metal can 1, three positive electrode materials 2 formed into a cylindrical shape by pressure are separately filled. . The positive electrode mixture 2 is obtained by mixing a manganese dioxide powder and a carbon powder and pressing the mixture into a hollow cylinder at a predetermined pressure using a molding die. In the hollow portion of the positive electrode mixture 2, a bottomed cylindrical separator 3 made of a nonwoven fabric of acetalized polyvinyl alcohol fiber is disposed. The gelled zinc negative electrode 4 produced by the above method is filled through the separator. In the gelled zinc negative electrode 4, a negative electrode current collector rod 5 made of brass is mounted so that its upper end protrudes from the gelled zinc negative electrode 4. An insulating gasket 6 made of a double annular polyamide resin is provided on the outer peripheral surface of the protruding portion of the negative electrode current collecting rod 5 and the upper inner peripheral surface of the metal can 1.
A ring-shaped metal plate 7 is disposed between the double annular portions of the insulating gasket 6, and a cap-shaped metal sealing plate 8 serving also as a negative electrode terminal is provided on the head of the current collecting rod 5. It is arranged to abut. The inside edge of the metal can 1 is sealed by the gasket 6 and the metal sealing plate 8 by bending the opening edge of the metal can 1 inward. The workability and impact resistance of each of the LR6 alkaline batteries assembled as described above were examined.

That is, the state of flow in the vessel wall of the filling device when each of the above-mentioned gelled zinc negative electrodes was filled in a battery was examined. In Table 1, ◎ is very good,
○ indicates good, Δ indicates acceptable, and × indicates unacceptable. In addition,-indicates that the amount of the gelling agent was small, sedimentation and separation of zinc particles occurred, and the gel did not work.

[0012]

[Table 1]

As shown in Table 1, when the gelling agent A is used alone, it becomes a gel at 2.5% or more.
It can be seen that the gel has a high viscosity because the ability to retain zinc particles is strong, and the workability is deteriorated. When the gelling agent B is added to this, workability is improved. This is because the chain polyacrylic acid dissolves and distributes on the surface of the non-melonized zinc alloy powder or cross-linked polyacrylate and acts as a lubricant, reducing friction with the wall of the filling device. It is considered that the filling of the gelled zinc negative electrode can be facilitated.

However, if the total of the gelling agent A and the gelling agent B exceeds 4.0%, the workability also deteriorates due to the high viscosity. In addition, in the case of a gel having a high viscosity which contains too much gelling agent, the supply of the electrolytic solution tends to be insufficient during discharge, and this is particularly noticeable during heavy load discharge, and there is a problem that the duration is reduced.

Next, the results of an examination on the impact resistance are shown.
The impact resistance test was performed by freely dropping a battery discharged with a discharge load of 2Ω from a height of 2 m and measuring the amount of change in operating voltage at that time with an oscilloscope. The results are shown in Table 2 (average value of n = 3). In Table 2, ◎ indicates a change of 100 mV.
Below, ○ is 100-200 mV, Δ is 200-500 mV
V and x indicate 500 mV or more.

[0016]

[Table 2]

As shown in Table 2, when the gelling agent A is used alone, the gelling agent A is used in an amount of 2.5% or more with respect to the electrolytic solution. 2.0%
As described above, if the amount of the gelling agent B is not more than 0.05% with respect to the electrolyte, the viscosity of the gel electrolyte becomes low and the zinc particles cannot maintain a stable state in the gel electrolyte. It turns out that the property is inferior.

When the gelling agent B is used alone, the impact resistance is not improved even if the amount added is increased. This is because the gelling agent A absorbs the electrolyte and expands, thereby improving the impact resistance by fixing the zinc particles, whereas the gelling agent B has a high viscosity due to the chain structure. This is considered to be because zinc particles cannot be retained.

In the above embodiment, the gelling agent A is
The dispersion viscosity of a 0.5% by weight aqueous solution at 25 ° C. is 15.0
Although a crosslinked polyacrylate of 00 cps was used, the same effect can be obtained if the aqueous dispersion viscosity is in the range of 10,000 to 20,000 cps. When the viscosity is out of this range, the viscosity of the gel electrolyte increases or decreases, which adversely affects the battery characteristics. For example, if the 0.5% by weight aqueous dispersion viscosity is less than 10,000 cps, the viscosity of the gelled zinc negative electrode is too low, and the zinc particles settle and separate. Further, the dispersion viscosity of a 0.5% by weight aqueous solution is 2
If it is not less than 000 cps, the gelled zinc negative electrode is too high in viscosity and deteriorates the discharge performance.

As for the gelling agent B, the dispersion viscosity of a 0.5% by weight aqueous solution at 25 ° C. is 9.0,
Although a chain polyacrylic acid of 00 cps was used, the same effect can be obtained when the aqueous dispersion viscosity is in the range of 3,000 to 12,000 cps, and if it deviates from this range, the viscosity of the gel electrolyte also increases. Or, the decrease causes the same problem as described above, and causes deterioration of the discharge performance due to separation of the gelled negative electrode and high viscosity. Therefore, the 0.1% of the gelling agent.
The dispersion viscosity of the 5% by weight aqueous solution is 10,000 to 20,000 cps for the crosslinked polyacrylate, and 3,000 to 12,000 c for the linear polyacrylic acid or a salt thereof.
ps.

When the particle size of the gelling agent is less than 100 μm for the crosslinked polyacrylate, the impact resistance is deteriorated, and
If the thickness is more than 00 μm, the dispersion of the filling amount becomes large.
A particle size range of 100 to 500 μm is preferred. On the other hand, in the case of chain polyacrylic acid or a salt thereof, even if the particle size exceeds 100 μm, the impact resistance is not so much improved, but rather the density of the gelled zinc negative electrode decreases and the amount of zinc as an active substance cannot be secured. Therefore, the particle size range is preferably 100 μm or less.

[0022]

As described above, according to the present invention,
The use of non-melonized zinc alloy powder achieves low pollution of the battery, and also improves the workability and impact resistance due to the use of non-melonized zinc alloy powder to improve the discharge performance. be able to.

[Brief description of the drawings]

FIG. 1 is a sectional view of an alkaline battery according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Metal can, 2 ... Positive electrode mixture, 3 ... Separator, 4 ... Gelled zinc negative electrode, 5 ... Negative electrode current collecting rod, 6 ... Insulating gasket, 7
... ring-shaped metal plate, 8 ... metal sealing plate.

Claims (2)

[Claims] 1. A zinc alkaline battery having a gelled zinc negative electrode containing a non-melonized zinc alloy powder, a gelling agent and an alkaline electrolyte, wherein the gelling agent has a 0.5% by weight aqueous dispersion dispersion viscosity at 25 ° C. 10,000-20,000
A crosslinked polyacrylate having a particle size of 100 cps and a particle size of 100 to 500 μm, and a 0.5% by weight aqueous solution dispersion viscosity at 25 ° C. of 3,000 to 12,
A zinc-alkaline battery comprising 000 cps and a chain polyacrylic acid or a salt thereof mainly having a particle size of 100 μm or less. 2. The addition concentration of the cross-linked polyacrylic acid salt is 2.0 to 3.5% by weight based on the alkaline electrolyte, and the addition concentration of the linear polyacrylic acid or salts thereof is 0. 2. The zinc alkaline battery according to claim 1, wherein the content is in the range of 0.5 to 0.5% by weight.