JPH05266881A - Alkaline battery and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide an alkaline battery without any use of amalgamated zinc by preliminarily positioning the zinc on the surface of a negative collector body where it is in contact with a negative electrode active material and an electrolyte. CONSTITUTION:A zinc layer 1a is laid on the internal surface of a negative electrode can 1. A negative electrode mix 2 is mainly composed of non- amalgamated zinc powder or non-amalgamated zinc alloy powder. A sealing agent 9 is laid between the can 1 and a gasket 8. Also, the application of plating, mask plating, deposition or the like to a negative collector body is available as a means for laying zinc or zinc containing an additive on the surface of the body where in contact with a negative electrode active material and an electrolyte. The negative electrode can 1l covered with zinc can be easily manufactured by using a can material where the zinc is hoop plated on a four-layer clad material of nickel, stainless steel, lead and zinc, or the copper surface of a three-layer clad material comprising nickel, stainless steel and copper, particularly in a button type alkaline battery where the negative collector body is used as the can 1 in common.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a mercury-free alkaline battery and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, in alkaline batteries using zinc as a negative electrode active material, mercury is attached to the surface of zinc. As a current collector for the negative electrode, brass is generally arranged in a cylindrical battery and copper is arranged in a button-shaped battery on the surface in contact with the negative electrode active material. When dissimilar metals, namely zinc and brass (Cu-Sn), or zinc and copper are present in the alkaline electrolyte, a local battery is formed, water in the electrolyte is decomposed, and hydrogen gas is emitted from the brass or copper surface. To occur. When mercury is added to zinc, the surface of the current collector is covered with mercury. The reason why mercury is attached to the surface of zinc to make it an amalgam is that since mercury has a higher hydrogen overvoltage than zinc, the hydrogen overvoltage of zinc itself increases, and the dissimilar metal contained in zinc with a low hydrogen overvoltage is easily removed from the amalgam surface. This is because it is difficult to construct the local battery because it is detached.

[0003]

However, in the conventional alkaline battery, since zinc hydride is used as the negative electrode active material, there is a problem of pollution when the battery is discarded. Further, in the conventional alkaline battery, even if an attempt was made to use zinc that was not hydrogenated as the negative electrode active material, zinc was not disposed on the surface of the negative electrode current collector that was in contact with the negative electrode active material and the alkaline electrolyte. Therefore, when zinc unprecipitated as an active material is brought into contact with this negative electrode current collector, gas is generated until the zinc is deposited on this current collector, or a metal mold is used when this current collector is pressed. Therefore, there is a problem that gas is generated from different metal impurities such as nickel mixed in the surface of the current collector.

Therefore, an object of the present invention is to obtain a mercury-free alkaline battery that does not use any zinc deuterated with mercury.

[0005]

In order to solve the above problems, in the present invention, zinc is provided in advance on the surface of the negative electrode current collector which is in contact with the negative electrode active material and the electrolytic solution. Further, when using zinc added with lead, indium, bismuth, gallium, tin, etc. as an active material so as to reduce the gas generation of zinc itself, the zinc alloy used as this active material and the negative electrode current collector It is desirable that the surfaces of the same have the same composition, and a further effect can be obtained.

As means for disposing zinc or zinc containing an additive on the surface of the negative electrode current collector that contacts the negative electrode active material and the electrolytic solution, plating on the negative electrode current collector, mask plating,
There is a vapor deposition method. In particular, in a button-type alkaline battery in which the negative electrode current collector also serves as a negative electrode can, the can material itself is a 4-layer clad material of nickel, stainless steel, copper and zinc, or a 3-layer clad of nickel, stainless steel and copper. By using a material in which the copper surface of the material is hoop-plated with zinc, a negative electrode can covered with zinc can be easily manufactured. Further, it is also possible to arrange the negative electrode can and the gasket by a method such as plating, vapor deposition or pressure bonding, adhesion, welding of zinc foil, etc. after the negative electrode can and the gasket are combined in the middle of the manufacturing process of the battery.

[0007]

[Function] Zinc is a metal with a large ionization tendency,
Similar to mercury, it has a high hydrogen overvoltage, and when zinc alone is immersed in an alkaline electrolyte, the amount of water decomposed is extremely small. However, when brass, copper, or the like, which is the current collector, comes into contact with zinc, the zinc potential is reached in the alkaline electrolyte, and water is rapidly decomposed. In the present invention, since the current collector is covered with zinc from the beginning, brass and copper are not exposed to the electrolytic solution at the zinc potential, and the gas generation is at the level of zinc alone, which is extremely high. Less. Thereby, an alkaline battery using mercury-free zinc as a negative electrode active material is put into practical use.

Zinc provided on the current collector also acts as an active material, but the zinc particles, which are the original active material, have a large surface area, and the zinc particles are consumed first in the battery reaction. Even if brass or copper on the surface of the current collector were exposed, no gas was generated during the discharge reaction. As soon as the discharge is stopped, zinc is deposited on the surface of the current collector, so that the state covered with zinc is maintained.

[0009]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partial sectional view of a silver oxide battery showing an embodiment to which the present invention is applied. The battery has an outer diameter of 6.8 mm and a height of 2.6 mm.

In the figure, reference numeral 1 is a negative electrode can, and a zinc layer 1a is provided on the inner surface of the negative electrode can 1. Reference numeral 2 denotes a negative electrode mixture, which is mainly composed of unarranged zinc powder or unarranged zinc alloy powder. Reference numeral 4 is an electrolytic solution impregnating material, and 5 is a separator. 6 is a positive electrode mixture, which is mainly composed of silver oxide. 7 is a positive electrode can
8 is a gasket. 9 is a sealant, and the negative electrode can 1
And the gasket 8.

(Embodiment 2) FIG. 2 is a partial sectional view of a negative electrode can which also serves as a negative electrode current collector, showing an embodiment to which the present invention is applied. In the figure, the negative electrode can 1 is composed of a nickel layer 1d, a stainless steel layer 1c, and a copper layer 1b from the outside, and a zinc layer 1a is disposed inside the negative electrode can 1. This Example 2
Then, a sheet-shaped sheet in which these four layers 1a, 1b, 1c, and 1d are clad is drawn by a press to finish the shape shown in FIG.

As shown in FIG. 2, since the zinc layer 1a is provided on the inner surface of the negative electrode can 1, even if the zinc layer 1a is brought into contact with the negative electrode mixture described in Example 1, no gas is generated. .. Using this negative electrode can 1, the silver oxide battery shown in Example 1 was assembled. Next, a conventional battery without the zinc layer 1a,
For the batteries of the present invention in which this zinc layer 1a was arranged, the self-discharge rates of the batteries were compared. This self-discharge rate is 60 ℃
20 batteries were discharged every 20 days, and calculated from the battery discharge capacity before storage and the battery discharge capacity of the stored number. As a result, the self-discharge rate decreased almost linearly with the storage period. The self-discharge rate of the battery of the present invention was 1-3% / 20 days, and the self-discharge rate of the conventional battery was 3-5% / 20 days. It was

The reason why the self-discharge rate of the battery of the present invention is smaller than that of the conventional battery is that since the zinc layer 1a is disposed on the inner surface of the negative electrode can 1, the negative electrode can 1 and the negative electrode mixture, which are the current collectors, are used. It is presumed that this is because the formation of a local battery between the powder and a certain unhydrogenated zinc powder is eliminated. (Embodiment 3) This embodiment 3 is all except that the zinc layer 1a contains at least one element of lead, indium, bismuth, gallium, aluminum and tin and an amount of 1 ppm or more and 2% or less. The same as in Example 2. The generation of gas from unfluorinated zinc in the alkaline electrolyte is at a level that causes almost no problem during the period in which the button type silver oxide battery is used for about 5 years.

However, in order to further suppress the gas generation due to the self-dissolution of the uncondensed zinc in the alkaline electrolyte and improve the reliability of the silver oxide battery, the above-mentioned additive is added to the uncondensed zinc. That is why it is included. When the amount of this additive is 1 ppm, the amount of gas generated is the same as that of unadded zinc, and when it is 2% or more, the amount of gas generated does not change. Therefore, the optimum range of addition amount is 1 ppm to 2
% Or less is suitable.

In the gas generation test from this zinc, 1 g each of non-added zinc powder and added zinc powder was put in a graduated glass tube together with a 30% ROH aqueous solution containing no ZnO, and the graduated glass tube was kept at 60 ° C. It is carried out by immersing it in a constant temperature water bath and reading the rising value of the scale every 20 days. The larger this scale is, the larger the amount of hydrogen gas generated for self-dissolving zinc is. A battery was assembled in the same manner as in Example 1. The negative electrode mixture 2 is the zinc layer 1
It is an unstructured zinc powder containing the same constituent elements as a.
Both the zinc powder and the zinc layer 1a contain indium of 0.
Contains 5%. When the self-discharge rate of the battery of the present invention assembled in this way was examined, it was found that the battery exhibited excellent storage characteristics at 1 to 1.5% / 20 days.

(Embodiment 4) The same as Embodiment 2 except that the zinc layer 1a in Embodiment 2 is formed by plating.
The same effect as in Example 2 was obtained. The plating may be performed by hoop plating the copper layer surface of the three-layer clad material including the nickel layer, the stainless steel layer, and the copper layer, and then pressing the negative electrode can. The inner surface of the manufactured negative electrode can may be galvanized.

(Embodiment 5) The plating in which the zinc layer 1a in Embodiment 2 contains one or more elements of lead, indium, bismuth, gallium, aluminum and tin in an amount of 1 ppm or more and 2% or less. All were the same as Example 3 except that they were layers, and the same effect as Example 3 was obtained.

(Embodiment 6) FIG. 3 is a partial cross-sectional view in which a zinc layer is provided on the inner surface of the negative electrode can according to the present invention. Zinc layer 1
The symbol a is a zinc foil having a thickness of 15 μm, which is punched out in a circular shape and fixed to the inner surface of the negative electrode can 1 by means such as welding, adhesion, and press-compression bonding, and the same effect as in Example 2 was obtained.

Example 7 In Example 6, the zinc layer 1
Example 3 is the same as Example 3 except that a is a zinc foil containing at least one element of lead, indium, bismuth, gallium, aluminum, and tin.
The same effect as was obtained.

[0020]

As described above in detail, since the present invention uses unhydrogenated zinc, it is possible to provide a mercury-free battery, help prevent pollution when the battery is discarded, and have a great industrial utility value.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a battery showing an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a negative electrode can that also serves as a negative electrode current collector, showing an embodiment to which the present invention is applied.

FIG. 3 is a partial cross-sectional view of a negative electrode can in which a zinc layer is provided on a part of the inner surface shown in an example to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Negative electrode can 1a Zinc layer 1b Copper layer 1c Stainless steel layer 1d Nickel layer 2 Negative electrode mixture 4 Electrolyte impregnating material 5 Separator 6 Positive electrode mixture 7 Positive electrode can 8 Gasket 9 Sealing agent

Claims (8)

[Claims] 1. An alkaline battery characterized in that zinc is provided on the surface of the negative electrode current collector which is in contact with the negative electrode active material and the electrolytic solution, and zinc particles containing no mercury are the main negative electrode active material. 2. The alkaline battery according to claim 1, further comprising a negative electrode can also serving as a negative electrode current collector, the negative electrode can being composed of four layers of nickel, stainless steel, copper and zinc. 3. The negative electrode can comprises nickel, stainless steel,
The alkaline battery according to claim 2, which is a four-layer clad material of copper and zinc. 4. The negative electrode can comprises nickel, stainless steel,
3. The alkaline battery according to claim 2, wherein a copper three-layer clad material is galvanized on the copper surface. 5. Zinc disposed on the surface of the current collector, which is in contact with the negative electrode active material and the electrolyte, contains 1 ppm or more and 2% or less of lead, indium, bismuth, gallium, aluminum and tin. The alkaline battery according to claim 1, claim 2, claim 3, or claim 4, wherein the alkaline battery contains an element. 6. A step of forming and manufacturing a negative electrode can that also serves as a negative electrode current collector, a step of coating a surface of the negative electrode can that does not come into contact with the negative electrode active material and the electrolytic solution with a plating mask, and the negative electrode can by plating, vapor deposition, etc. The step of adhering zinc or an alloy mainly containing zinc to the surface not masked, the step of removing the plating mask adhering to the negative electrode can, and the negative electrode can manufactured by the above-mentioned steps The alkali according to claim 2, claim 4 or claim 5, further comprising a step of manufacturing a battery by combining with other components of the battery such as an active material, an electrolytic solution, a separator, a positive electrode can and a gasket. Battery manufacturing method. 7. A process of assembling a negative electrode can made of a clad material of nickel, stainless steel and copper also serving as a negative electrode collector with a gasket made of plastic with a sealing agent such as asphalt, epoxy resin, polyamide resin, rubber or the like, plating , A step of depositing zinc or a zinc alloy on the surface of the negative electrode can contacting the negative electrode active material and the electrolytic solution by means such as vapor deposition, and the negative electrode can in combination with the gasket to which the zinc is adhered The manufacturing of an alkaline battery according to claim 2, 4, or 5, further comprising a step of manufacturing a battery in combination with other battery constituents such as a negative electrode active material, a separator, and an electrolytic solution. Method. 8. The alkaline battery according to claim 1, wherein a zinc foil is provided on the inner surface of the negative electrode can that also serves as the negative electrode current collector by means such as press-compression bonding, adhesion, and welding.