JPH0765817A - Alkaline battery - Google Patents

Abstract

(57) [Summary] [Objective] In an alkaline battery using a gel negative electrode in which zinc powder is dispersed in a gel electrolyte composed of an alkaline electrolyte and a gelling agent, continuous vibration and impact are continuously applied for a long time. Also provides an alkaline battery having stable discharge characteristics. [Structure] A crosslinked polyacrylic acid salt-type water-absorbing polymer having a carboxylate group and a crosslinked branched polyacrylic acid or a salt thereof are used in combination, and further, indium, tin, bismuth oxide, hydroxide, and sulfide It is characterized in that at least one kind is added to the electrolytic solution to obtain a gel electrolyte.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkaline battery using a gelled negative electrode, and more particularly to improvement of a gelling agent for the gelled negative electrode.

[0002]

2. Description of the Related Art Conventionally, a cross-linked branched polyacrylic acid or its sodium salt is generally used as a gelling agent. The cross-linked branched polyacrylic acid used as a gelling agent has a high viscosity to uniformly disperse the zinc powder in the gelled negative electrode. (For example, Japanese Patent Laid-Open No. 2-1190
Further, the contact between zinc particles and the current collector is increased to enhance the current collecting effect.

[0003]

In order to suppress the corrosion of zinc and maintain the storage characteristics of the battery, zinc hydride prepared by adding mercury to zinc powder has been conventionally used. Further, this mercury has a function of increasing the contact property between zinc particles and the zinc particles and the current collector to enhance the current collecting effect. However, due to recent environmental pollution problems, it is necessary to reduce mercury contained in the negative electrode of the battery. For this reason, if mercury is removed from the zinc powder, the contact between the zinc particles will deteriorate, so if a continuous vibration / shock is applied for a long time, the zinc particles in the gelled negative electrode will be The electric effect becomes worse. Further, when vibration and impact are applied while discharging, the surface of the zinc particles becomes zinc oxide due to the discharge reaction and the particles become smaller, so the current collecting effect becomes worse. For this reason, when vibration and impact were continuously applied for a long time while discharging, the voltage suddenly dropped and the discharge performance deteriorated.

According to the present invention, two kinds of gelling agents are used in combination, and further, at least one oxide, hydroxide or sulfide of a metal selected from indium, tin or bismuth is contained. Strong vibration during discharge
It is an object of the present invention to provide an alkaline battery that can withstand a shock for a long time.

[0005]

The present invention provides a gelled negative electrode comprising an alkaline electrolyte, a gelling agent, and zinc powder for an alkaline battery, which has a dispersion viscosity of 15% by weight of a 0.5 wt% aqueous solution at 25 ° C. as a gelling agent. Cross-linked polyacrylate-type water-absorbing polymer having a carboxylate group whose main particle size is more than 1,000 cps and whose particle size is 100 to 900 microns, and 0.5% by weight aqueous dispersion viscosity at 25 ° C. A cross-linked branched polyacrylic acid having a carboxylic acid mainly having a particle size of 15,000 cps or more and a particle diameter of 100 microns or less or a cross-linked branched polyacrylic acid salt having a carboxylic acid group is used in combination, At least one kind of oxide, hydroxide or sulfide of a metal selected from indium, tin and bismuth is added and contained.

[0006]

The present invention occurs when a conventional gelled negative electrode is used by using the above two types of gelling agents together with at least one metal compound selected from indium, tin and bismuth. It is intended to improve the deterioration of vibration resistance. The gelling agent of cross-linked and branched polyacrylic acid swollen in the gelled negative electrode or its salt has a poor elastic force, so that it is a drawback that contact between zinc particles is deteriorated by impact. Further, since the zinc particles become smaller due to the discharge, a space is created between the particles, and contact is deteriorated when vibration or impact is applied during the discharge. The disadvantage is that the space is filled by adding a cross-linked polyacrylate type water-absorbing polymer having a high liquid retention and an excellent elastic force, and further, a gel-like composition in which the inorganic compound according to claim 3 is dispersed. In the negative electrode, a part of it is electrodeposited on the surface of the zinc alloy by the principle of displacement plating, which improves the contact property between zinc particles, and can withstand vibration and shock for a long time while discharging. .

[0007]

EXAMPLE FIG. 1 is a half sectional view of a cylindrical alkaline battery LR6 used in an example of the present invention. The positive electrode mixture 1 made of manganese dioxide and graphite was put in the metal case 6 and separated.
After inserting, the gelled negative electrode 2 is injected into the separator-3. Negative electrode current collector 4 in which resin sealing body 8 and bottom plate 9 are integrated
Is inserted into the gelled negative electrode to form a unit cell. Reference numeral 5 is a positive electrode terminal cap, and 7 is an outer can.

The above-mentioned gelled negative electrode is composed of an alkaline electrolytic solution containing zinc oxide and a 40% potassium hydroxide aqueous solution, a gelling agent, and zinc powder twice as much as the electrolytic solution.

Next, examples of the present invention will be described. As a gelling agent, the dispersion viscosity of a 0.5 wt% aqueous solution at 25 ° C. is 20,000 cps, and the particle size is 100 to 90.
Crosslinked polyacrylate-type water-absorbing polymer (gelling agent A) having a carboxylate group having an average particle size of 0 micron and having a mean particle size of 500 microns, and 0.5% by weight at 25 ° C.
An aqueous solution having a dispersion viscosity of 20,000 cps, a crosslinked branched polyacrylic acid (gelling agent B) having a carboxylate group having a particle size of 100 μm or less and an average particle size of 10 μm, and an electrolyte solution of 100 g are used. On the other hand, the addition amount of the gelling agent shown in (Table 1) and 0.2 g of indium hydroxide were added to prepare 300 g of a gelled negative electrode. 20 cylindrical alkaline batteries LR6, into which the gelled negative electrode was injected, were prepared and subjected to a vibration test. In the vibration test, the discharge sustaining voltage is measured when the battery is discharged with a load resistance of 1Ω and a height of 2 cm is dropped 100 times for 1 hour. The test results are shown in (Table 1).

[0010]

[Table 1]

In Table 1, ⊚ indicates a normal voltage behavior (voltage drop within 100 mV), ∘ indicates a normal voltage behavior (voltage drop within 200 mV), and × indicates a sharp voltage drop (voltage drop). (500 mV or more), △ is not completely dropped, but there is a sign that it will drop (voltage drop 200 mV ~
500 mV). As a result of the test, an abnormal voltage drop was observed in the battery using each gelling agent alone,
When a certain amount of both gelling agent A and gelling agent B were used together, normal voltage behavior was exhibited. This is because the cross-linked and branched polyacrylic acid has poor elasticity, and since zinc particles become smaller due to discharge, a drop impact creates a space between the zinc particles, resulting in poor contact. Fall to. Therefore, by adding a water-absorbing polymer having a high liquid-retaining power and an excellent elastic force, the network between zinc particles becomes finer and a sharp drop in voltage can be improved. However, even if the water-absorbent polymer is used alone, the impact resistance becomes poor.

This is because the water-absorbing polymer has a strong liquid-retaining power, so that the liquid required for discharge is insufficient, and at the end of discharge, the electrolytic solution for the reaction becomes difficult or insufficient to be smoothly supplied, and also the vibration is generated. Is added, the voltage drops suddenly. Furthermore, when the total amount of each gelling agent added is 1.10% by weight or less based on the gel electrolyte, the viscosity of the gel electrolyte is low, so that the zinc particles are stably dispersed in the gel electrolyte. Can't keep. Further, if the total amount of the gelling agent added exceeds 4.0% by weight with respect to the gel electrolyte, there is a problem that the viscosity of the electrolyte is too high and the discharge does not proceed smoothly. From this test result, the addition amount range in which two kinds of gelling agents can be used in combination is that the addition amount range of the gelling agent A is 1.0 to 3.0% by weight with respect to the electrolytic solution, and the addition amount of the gelling agent B is The range was determined to be 0.1-1.0% by weight. In this region, the performance of the alkaline battery against impact resistance is stable.

If the dispersion viscosities of the gelling agent A and the gelling agent B in 0.5% by weight aqueous solution are less than 15,000 cps, the addition concentration of the gelling agent A is 1.0 to 3.0% by weight. In a gelled negative electrode in which the concentration of the gelling agent B added is 0.1 to 1.0% by weight, the viscosity is too low, and the zinc powder particles settle out and separate. The dispersion viscosity should be above 15,000 cps. Furthermore, if the particle size of the gelling agent A is 100 microns or less,
Can no longer withstand vibration and shock, and has a particle size of 900
When the particle size exceeds micron, the flowability of the gelled negative electrode deteriorates and the dispersion of the filling amount increases, so that the particle size range of 100 to 900 micron is preferable. On the other hand, the particle size of the gelling agent B is 10
Even if it exceeds 0 micron, it cannot withstand vibration and impact, and since the density of the gelled negative electrode decreases and the amount of zinc active material cannot be secured, the particle size range is preferably 100 micron or less.

Next, the effect of addition of the metal oxide, hydroxide or sulfide additive will be described.

A gel electrolyte containing indium hydroxide was prepared by using the two kinds of gelling agents used in the above examples in combination. Actually, the gelling agent A is added to 100 g of the electrolytic solution.
2.0 g, gelling agent B 0.5 g, and indium hydroxide in the amounts shown in Table 2 were added to give 300 g.
A gelled negative electrode was prepared. Using the gelled negative electrode thus prepared, an AA alkaline battery LR6 was prepared and the same vibration test as in Example 1 was conducted. The test results (Table 2)
It was shown to.

[0016]

[Table 2]

It was confirmed that in the alkaline electrolyte, a part of indium hydroxide was ionized and electrodeposited on the surface of the zinc alloy powder by the principle of displacement plating. It is considered that the indium electrodeposited on the zinc powder particles has a function of improving the contact property between the zinc powder particles and strengthening the network of the zinc particles. For this reason, even in the vibration test while discharging, the discharge is normal without a sharp drop in voltage. Furthermore, the effect of the amount of indium hydroxide added to the zinc alloy is from 0.005 wt% to 0.5
The result of the vibration test becomes better with the increase of the addition amount up to the weight%, but further addition is not so good.
Note that the addition effect was not exhibited at 0.001% by weight or less. Similar effects were obtained with oxides and sulfides instead of indium hydroxide.

Similar effects were obtained for tin and bismuth.

[0019]

As described above, by using the present invention, it is possible to provide an alkaline battery having excellent resistance to vibration and shock during discharge.

[Brief description of drawings]

FIG. 1 is an AA alkaline battery L according to an embodiment of the present invention.
Longitudinal section of R6

[Explanation of symbols]

 1 Positive Electrode Mixture 2 Gel Negative Electrode 3 Separator 4 Current Collector 5 Positive Electrode Terminal Cap 6 Metal Case 7 Exterior Can 8 Resin Sealing Body 9 Bottom Plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Asaoka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. An alkaline battery comprising a gelled negative electrode containing zinc alloy powder, a gelling agent and an alkaline electrolyte,
As the gelling agent, the dispersion viscosity of a 0.5 wt% aqueous solution at 25 ° C. is 15,000 cps or more, and the particle size is 1
A crosslinked polyacrylate-type water-absorbing polymer having a carboxylate group, which is mainly in the range of 00 to 900 microns, and a 0.5 wt% aqueous dispersion viscosity at 25 ° C. of 1
A cross-linked branched polyacrylic acid having a carboxylic acid mainly having a particle size of 5,000 cps or more and having a particle size of 100 microns or less, or a cross-linked branched polyacrylic acid salt having a carboxylic acid group is used in combination, An alkaline battery characterized in that the gelled negative electrode contains at least one oxide, hydroxide or sulfide of a metal selected from indium, tin and bismuth. 2. The addition concentration of the crosslinked polyacrylate-type water-absorbing polymer is 1.0 to 1.0 with respect to the alkaline electrolyte.
The alkaline battery according to claim 1, wherein the addition concentration of the cross-linked branched polyacrylic acid or its salt is in the range of 0.1 to 1.0% by weight. 3. The addition concentration of at least one of the oxides, hydroxides, and sulfides of the metal selected from indium, tin, and bismuth is 0.
The alkaline battery according to claim 1, which is in a range of 005 to 0.5% by weight.