JP3371577B2 - Alkaline battery - Google Patents

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 for alkaline batteries, for example, alkaline dry batteries. The cross-linked branched polyacrylic acid used as a gelling agent is
Due to its high viscosity, the zinc powder in the gelled negative electrode is uniformly dispersed, and further, the zinc particles work together to increase the contact property between the zinc particles and the current collector to enhance the current collecting effect (see, for example, Japanese Patent Laid-Open Publication No. HEI-HEI-KOKAI). No. 2-119053).

Further, in order to suppress the corrosion of zinc and maintain the storage characteristics of the battery, zinc fluoride, which is obtained by adding mercury to zinc powder, has been conventionally used. This mercury is zinc particles,
It also had the effect of increasing the contact property between the zinc particles and the current collector to enhance the current collecting effect.

[0004]

However, due to recent environmental pollution problems, it has become necessary to use no mercury in the negative electrode of the battery. Therefore, when mercury is removed from the zinc powder, the contact properties of the zinc particles drop,
When the battery is subjected to continuous vibration / shock for a long time, the zinc particles in the gelled negative electrode are hardened in the negative electrode, and the current collecting effect is deteriorated. Further, when discharged under such conditions, the surface of the zinc particles becomes zinc oxide due to the discharge reaction and the particles become smaller, so that the current collecting effect becomes worse.
Therefore, when vibration and impact are continuously applied for a long time while discharging, a phenomenon occurs in which the voltage suddenly drops and the discharging performance deteriorates.

The present invention provides an alkaline battery which can endure strong vibration and shock during discharge for a long time by using a specific gelling agent together, and a gel electrolyte containing these gelling agents. Further, by providing at least one of oxides, hydroxides and sulfides of metals selected from indium, tin and bismuth, an alkaline battery capable of further improving vibration resistance and impact characteristics is provided. The purpose is to

[0006]

Means for Solving the ProblemsAlkaline batteries
To achieve the above objectives, ALucari electrolyte, gelling agent
And a gelled negative electrode containing zinc or zinc alloy powder,
As a gelling agent, 0.5% by weight aqueous solution at 25 ° C.
Diffusivity is over 15,000 cps and particle size is 10
Cross-linked polyac, mainly for 0-900 microns
Lilate type water-absorbing polymer and 0.5 weight at 25 ° C
Amount% aqueous dispersion viscosity20More than 1,000 cps
Chain polyacrylic acid or its saltUsed,
Furthermore, specify the concentration of each addition and the total concentrationWhat to do
Is characterized by.

Specifically, the addition concentration (X) of the crosslinked polyacrylate type water-absorbing polymer is within the range of 1.0% by weight ≤X≤3.0% by weight with respect to the alkaline electrolyte.
The addition concentration (Y) of the linear polyacrylic acid or salt thereof is within the range of 0.05% by weight ≦ Y ≦ 1.0% by weight, and the sum (T) of the addition concentrations is based on the gel electrolyte. which Te is in the range of 1.25 wt% ≦ T ≦ 3.5 wt%
Is.

Further, in the present invention, in the gelled negative electrode using the above gelling agent, the gelled negative electrode is further made of an oxide, hydroxide or sulfide of a metal selected from indium, tin and bismuth. It is preferable to contain at least one selected compound.

When the compound contains at least one compound selected from oxides, hydroxides and sulfides of metals selected from the above-mentioned indium, tin and bismuth, the total content thereof is zinc or zinc alloy. 0 for powder.
005-l. It is preferably in the range of 0% by weight.

[0010]

According to the present invention, by using the gelling agent in combination, deterioration of vibration resistance and impact characteristics which would occur when a conventional gelled negative electrode is used is prevented, and a gel containing the gelling agent is also used. Vibration resistance and impact resistance by using at least one compound selected from the oxides, hydroxides and sulfides of metals selected from indium, tin and bismuth for the negative electrode. It can be further improved.

The crosslinked polyacrylate type water-absorbing polymer swollen in the gelled negative electrode has high elasticity and liquid retention,
Since the gelling agent particles do not completely dissolve in the alkaline electrolyte and remain in the gel electrolyte, the zinc or zinc alloy particles are prevented from settling and the contact points between the zinc or zinc alloy particles are increased to collect the particles. The electric effect is enhanced. However, since this water-absorbing polymer has too high a liquid-retaining ability, it is difficult to release it when the electrolytic solution is held, and thus there is a drawback that the electrolytic solution required for discharging cannot be smoothly supplied into the battery at the end of discharge.
Also, the contact points between zinc or zinc alloy particles increase,
Since the adhesiveness is weak, zinc or zinc alloy particles flow when subjected to continuous vibration or impact. In order to compensate for these drawbacks, if a linear polyacrylic acid having spinnability or a salt thereof is added to this water-absorbing polymer, the viscosity of the gelled negative electrode and It is possible to secure contact between zinc or zinc alloy particles, and also to prevent liquid shortage. This is because the linear polyacrylic acid having spinnability or its salt has a high viscosity, and thus a high viscosity can be obtained even in a small amount. Furthermore, it is presumed that the zinc or zinc alloy particles are tightly wrapped and fixed as a lump due to the spinnability and adhesiveness, and the precipitation or flow of the zinc or zinc alloy particles is suppressed to strengthen the network.

By using these two types of gelling agents in combination, the elasticity and spinnability of each gelling agent can be fully utilized, the contact between zinc or zinc alloy particles is improved, and the network is improved. Will also be strengthened. Therefore, it is possible to withstand vibration and shock for a long time while discharging.

Furthermore, in a gelled negative electrode in which at least one compound selected from oxides, hydroxides and sulfides of metals selected from indium, tin and bismuth is dispersed, a part of the compound is used. Is deposited on the surface of zinc or a zinc alloy by the principle of displacement plating, and the contact property between zinc or zinc alloy particles is improved, so that the vibration resistance / impact characteristics for a long time while discharging can be improved.

[0014]

EXAMPLES The present invention will be described in detail below based on examples and comparative examples.

FIG. 1 is a half-cut vertical sectional view of a cylindrical AA alkaline battery LR6 used in an embodiment of the present invention. Positive electrode mixture 2 consisting of manganese dioxide and graphite in metal case 1
Then, after inserting the separator 3, the gelled negative electrode 4 is injected into the separator 3. The resin sealing body 5 in which the negative electrode current collector 6 and the bottom plate 7 are integrated is inserted into the gelled negative electrode to form a unit cell.

The above gelled negative electrode contains zinc oxide and 40%
It is composed of an alkaline electrolyte containing an aqueous solution of potassium hydroxide, a gelling agent, and zinc or zinc alloy powder in an amount twice as much as the weight of the electrolyte.

First, as a gelling agent, the dispersion viscosity of a 0.5 wt% aqueous solution at 25 ° C. is 20,000 cps,
Cross-linked sodium polyacrylate (gelling agent A) having an average particle size of 500 to 500 microns and a gel strength of 30,000 guin / cm ² , and a particle size of 0. 5% by weight aqueous solution has a dispersion viscosity of 40,000 cps and a molecular weight of 2,500,000 to 500.
In addition, a linear sodium polyacrylate (gelling agent B) having an average particle size of 100 to 900 μm and an average particle size of 500 μm was used.
A gelled negative electrode was prepared by adding the gelling agent in the amount shown in 1 and the zinc or zinc alloy powder in an amount twice that of the gelling agent.

Twenty cylindrical AA alkaline batteries LR6, each containing a predetermined amount of the gelled negative electrode thus obtained, were prepared and subjected to a vibration test. The vibration test was performed by measuring the fluctuation range of the discharge curve when discharging 100 times from a height of 2 cm per minute for 1 hour while discharging with a load resistance of 1Ω. The gel strength of the gelling agent was measured by the following method.

The amount (A g / g) of the water-absorbent polymer absorbed in physiological saline was measured in advance by the tea bag method.
A 75% physiological saline solution corresponding to the liquid absorption amount A was placed in a beaker, and 1 g of the water-absorbing polymer was added to the beaker with stirring to uniformly absorb the water-absorbing polymer to prepare a water-absorbent gel having a smooth surface. The water-absorbent gel was kept warm at 25 ° C., and the gel strength was measured using a neocard meter under the following operating conditions.

Load: 200g Diameter of pressure sensitive shaft: 8mmφ Pressure-sensitive axis descending speed: 0.36 cm The results of the vibration test conducted by the above method are shown in Table 1.

[0021]

[Table 1]

Table 1 shows the results of testing by making a gel electrolyte with two kinds of gelling agent A and gelling agent B. In the table, ◎ indicates normal discharge power (voltage fluctuation range within 100 mV), ○
Is a normal discharge curve (voltage fluctuation range within 200 mV),
× indicates a sharp drop in voltage on the discharge curve (voltage fluctuation range of 500 mV or more), Δ indicates that it does not completely drop but there is a sign of decrease (voltage fluctuation range of 200 m)
V to 500 mV). According to these results, the voltage drops sharply with each gelling agent alone, but when gelling agent A and gelling agent B are used together, the behavior of the voltage can be improved, and the vibration and shock resistance characteristics are improved. You can see that it can be improved. However, if the amount of any one of the gelling agents added is too large, the vibration resistance / impact characteristics deteriorate.

When the gelling agent A having high elasticity was used alone, the fluctuation range of discharge was increased, and the duration of discharge was shortened by about half as compared with the normal curve marked with ⊚. This is because the liquid retention capacity of the water-absorbent polymer causes a liquid shortage at the end of discharge, which makes it difficult or insufficient to supply the electrolyte solution for the reaction, and the discharge is not performed smoothly. The voltage suddenly drops when vibration is applied. Further, since it is a gelling agent lacking adhesiveness, when vibration or impact is applied, the zinc or zinc alloy particles flow, the number of contact points decreases, and current collection deteriorates.

When the gelling agent B having spinnability is used alone, it is inferior in elasticity and the gelling agent itself does not remain as particles, so that the zinc or zinc alloy particles are not in good contact with each other and vibration or impact is applied. Zinc or zinc alloy particles settle in the gelled negative electrode, the current collecting effect deteriorates, and the voltage suddenly drops.

However, when these two types of gelling agents are used in combination, the excellent elasticity and water absorption of the gelling agent A improve the contact between particles, and the addition of the gelling agent B improves the spinnability of the particles. By making the network of zinc or zinc alloy particles more viscous and stronger, it is possible to prevent the flow of zinc or zinc alloy particles which occurs when vibration or shock is applied, and improve the sharp drop in voltage. In addition, since the addition amount of the gelling agent A can be reduced by adding the gelling agent B, it is possible to prevent the liquid shortage at the end of discharge, which is caused by the liquid holding power of the gelling agent A.

Furthermore, the total amount of each gelling agent added is 1. If it is less than 25% by weight, the viscosity of the gel electrolyte is low, so that zinc or zinc alloy particles settle in the gel electrolyte and a stable dispersed state cannot be maintained. If the total amount of the gelling agent added exceeds 3.5% by weight with respect to the gel electrolyte, the viscosity of the electrolyte is too high and the discharge cannot proceed smoothly. From this test result, the addition amount range in which two kinds of gelling agents can be used in combination is such that the addition concentration (X) of the gelling agent A to the electrolytic solution is 1.0 ≦ X.
By setting the range of ≦ 3.0% by weight and the addition concentration (Y) of the gelling agent B in the range of 0.05 ≦ y ≦ 1.0% by weight,
It has been found that the performance of the alkaline battery with respect to impact resistance characteristics is stable.

The dispersion viscosity of a 0.5 wt% aqueous solution of gelling agent A is less than 15,000 cps, and that of gelling agent B is 0.5.
When the weight% aqueous dispersion viscosity is less than 20,000 cps, the addition concentration of the gelling agent A is 1.0 ≦ X ≦ 3.0% by weight.
, The addition concentration of the gelling agent B is 0.05 ≦ Y ≦ l. 0
Since the viscosity of the gelled negative electrode in the range of wt% is too low, zinc or zinc alloy powder particles were precipitated and separated. Therefore, the dispersion viscosity of the 0.5% by weight aqueous solution of the gelling agent A should be 15,000 cps or more and the dispersion viscosity of the 0.5% by weight aqueous solution of the gelling agent B should be 20,000 cps or more.

Furthermore, if the particle size of the gelling agent A is less than 100 microns, it will not be able to withstand vibration and shock, and if the particle size exceeds 900 microns, the fluidity of the gelled negative electrode will deteriorate and the filling amount will be reduced. Variation will increase,
The density of the gelled negative electrode also decreased. Therefore, 100 to 900
The micron particle size range is preferred.

Regarding the gel strength of the gelling agent A,
When it is in the range of 15,000 to 50,000 dynes / cm ² , the elasticity, which is the characteristic of the water-absorbent polymer, is most effective for vibration resistance and impact, and the gelling agent B has the necessary spinnability. The molecular weight is 2.5 million to 50
It is preferable to use an uncrosslinked polymer having a molecular weight of 0,000.

In this example, the sodium salt of polyacrylic acid was used as both the gelling agent A and the gelling agent B, but other salts (eg potassium polyacrylate) may also be used. The same effect was obtained by using polyacrylic acid in the agent B.

Next, an oxide of a metal selected from indium, tin and bismuth as an additive used in the present invention,
The effect of adding hydroxide or sulfide will be described.

A gel electrolyte containing the two types of gelling agents used in the above examples and indium hydroxide was prepared. A gelled negative electrode was prepared by adding 2.0% by weight of gelling agent A, 0.4% by weight of gelling agent B, and indium hydroxide in the amounts shown in Table 2 to the electrolytic solution. Using the gelled negative electrode thus prepared, an AA alkaline battery LR6 was prepared and a vibration test similar to that in the above-mentioned example was conducted. The results are shown in Table 2.

[0033]

[Table 2]

Table 2 shows the voltage fluctuation range of the discharge curve when the vibration test was conducted on the battery prepared by using the gelled negative electrode to which the gelling agent A, the gelling agent B and the indium hydroxide were added. From these results, it is found that the addition of indium hydroxide reduces the voltage fluctuation range. In the alkaline electrolyte, part of indium hydroxide is ionized and electrodeposited on the surface of zinc or zinc alloy by the principle of displacement plating. The indium electrodeposited on zinc or zinc alloy particles is the same as zinc or zinc alloy particles. It is thought that it has the function of improving the contact property of (3) and strengthening the network of zinc or zinc alloy particles. For this reason, even in the vibration test while discharging, the voltage does not drop sharply, and the discharge is normal with little fluctuation in voltage. Furthermore, the effect of the amount of indium hydroxide added to zinc or a zinc alloy is
0.005% by weight to l. Up to 0% by weight, the vibration test results improved as the amount of addition increased, but further addition did not improve. If it is less than 0.001% by weight, the effect of addition does not appear.

With respect to the effect of such addition, similar results can be obtained by addition of indium oxide, sulfide, tin oxide, bismuth oxide, hydroxide and sulfide, and composite addition of these compounds. Was obtained.

[0036]

As described above, according to 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.
The longitudinal cross-sectional view of R6.

[Explanation of symbols]

l Metal case 2 Positive electrode mixture 3 separator 4 Negative electrode 5 Resin sealing plate 6 Negative electrode current collector 7 Bottom plate

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-1-231272 (JP, A) JP-A-2-119053 (JP, A) JP-A-59-215663 (JP, A) JP-A-2- 267863 (JP, A) JP 4-366550 (JP, A) JP 6-84521 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 4/06-4 / 08 H01M 4/62

Claims (3)

(57) [Claims] 1. An alkaline battery using a gelled negative electrode in which zinc or zinc alloy powder is dispersed in a gelled electrolytic solution comprising an alkaline electrolytic solution and a gelling agent , wherein the gelling agent is 0 at 25 ° C. Dispersion viscosity of a 5% by weight aqueous solution is 15,000 cps or more and the particle size is 10
A crosslinked polyacrylate type water-absorbing polymer mainly composed of 0 to 900 microns and a linear polyacrylic acid or a salt thereof having a 0.5 wt% aqueous solution dispersion viscosity at 25 ° C. of 20,000 cps or more. Including the rack
Addition concentration of bridge polyacrylate type water-absorbing polymer (X)
Is 1.0% by weight ≦ X ≦ 3.0 weight with respect to the alkaline electrolyte
Is within the range of 40% by weight, and the linear polyacrylic acid or
The addition concentration (Y) of the salt is 0.05% by weight ≦ Y ≦ 1.0
It is in the range of wt%, and the total (T) of each addition concentration is gel.
1.25 wt% ≤ T ≤ 3.5 wt% of the electrolyte solution
Alkaline battery characterized by being in the range . 2. The gelled negative electrode comprises indium, tin and
And oxides of metals selected from bismuth and bismuth
And at least one compound selected from sulfides
The alkaline battery according to claim 1, containing the same . 3. The total content of at least one compound selected from oxides, hydroxides and sulfides of metals selected from indium, tin and bismuth is based on zinc or zinc alloy powder. 0.005-l. 0% by weight
The alkaline battery according to claim 2 , which is within the range of.