JP2946894B2 - Zinc 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 a zinc-alkaline battery in which a negative electrode active material is a mercury-free zinc alloy powder, generates less hydrogen gas in the battery, and has improved liquid leakage resistance.

[0002]

2. Description of the Related Art In an alkaline battery using zinc as a negative electrode active material, hydrogen gas is generated during the storage of the battery due to the corrosion reaction of zinc, the internal pressure of the battery increases, and the electrolytic solution is pushed out to the outside. There is a problem in that the battery may explode, and in some cases, the battery may be ruptured.

As a countermeasure, it has been common practice to use a zinc alloy powder to which mercury is added for the purpose of suppressing the generation of hydrogen gas on the surface of zinc as a negative electrode active material. Conventionally, copper or a copper alloy has been generally used as the current collector of the zinc negative electrode, and the surface of the current collector has been turned into mercury by contact with the zinc negative electrode. For this reason, generation of hydrogen gas could be suppressed as in the case of the zinc negative electrode even if the collector had some oxides or impurities on the surface thereof.

Further, conventionally, in order to remove impurities on the surface of the current collector and suppress generation of hydrogen gas, the surface of the current collector has been subjected to alkali degreasing cleaning, acid or hydrogen peroxide before assembling the battery. A method of polishing by chemical polishing has been used.

[0005] On the other hand, with concerns about the environmental destruction caused by industrial products worldwide, there has been a strong demand for reduction of mercury contained in alkaline batteries or development of batteries free of mercury.

[0006]

However, the above-mentioned methods of cleaning the current collector and chemical polishing also make
When a zinc alloy powder containing no mercury is used, an alkaline battery having excellent corrosion resistance, little variation in product quality, and achieving a high level of stabilization has not been obtained.

The reason is described below. For example, in the case of a cylindrical alkaline manganese battery, a collector rod made of a zinc alloy such as copper or brass is generally used as a negative electrode current collector, but this collector rod has a predetermined wire diameter. In general, those drawn by several stages of wire drawing manufacturing processes are used. In the manufacturing process, fine pieces of metal such as iron and nickel adhere to the surface of the current-collecting rod made by such drawing, and the fine pieces are
In many cases, it is stuck to the surface of the current collector rod.

The current collecting rod is electrically connected to the bottom plate serving as the negative electrode terminal, and is incorporated into the battery through several steps of manufacturing to form a sealing portion. Even during such an assembling process, metal fine powder such as iron and nickel adheres, and moreover, the fine powder often penetrates and adheres to the surface of the current collecting rod.

Therefore, even if the surface of the current collector is polished by alkaline degreasing or chemical polishing using an acid or hydrogen peroxide before assembling the battery, fine metal powder adheres in the assembling process of the battery, and after the assembling of the battery, It becomes a factor of generating hydrogen gas.

Particularly, in a battery using a zinc alloy powder containing no mercury for a negative electrode, since there is no mercury having an excellent anticorrosion effect, the corrosion reaction of the zinc alloy is remarkably accelerated, and the generation of hydrogen gas is increased. Become.

The present invention solves the above-mentioned conventional problems. Even if a zinc alloy powder containing no mercury is used for the negative electrode of an alkaline battery, it is possible to improve the corrosion resistance by suppressing the generation of hydrogen gas and improve the resistance to liquid leakage. It is an object of the present invention to provide a mercury-free alkaline battery having excellent easiness and reduced variation in product quality.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to increase the hardness of the surface of a current collecting rod to effectively prevent the adhesion of impurities.

Conventionally, a current collector rod has been made of a copper or copper alloy wire having a Vickers hardness of about 130. For this reason, impurities are easily fixed in the wire-drawing manufacturing process of the current collector rod and the battery assembling process, which significantly promotes the corrosion reaction of the zinc alloy and easily increases the generation of hydrogen gas.

In the alkaline battery of the present invention, by using a current collecting rod made of a material such as copper or copper alloy having a Vickers hardness of 150 or more, impurities adhered to the surface of the current collecting rod are reduced to reduce the generation of hydrogen gas. It is intended to reduce it.

[0015]

[Function] When a fine powder of heavy metal such as iron or nickel adheres to the surface of a current collecting rod made of copper or a copper alloy, the metal has a small hydrogen overvoltage. Occurs.

In particular, when mercury-free zinc alloy powder is used as a negative electrode active material for an alkaline battery, hydrogen gas is remarkably generated as compared with a zinc alloy powder that has been turned into mercury. Therefore, in the current collecting rod, by using a current collecting rod made of a material such as copper or copper alloy having a Vickers hardness of 150 or more, it is possible to attach iron, nickel, and the like in a wire drawing manufacturing process of the current collecting rod and a battery assembling process. By reducing the metal powder from biting and sticking to the surface of the current collector rod, the generation of hydrogen gas is suppressed, the leakage resistance is excellent, the variation in battery performance is reduced, and the quality of mercury-free alkaline batteries is stabilized. be able to.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A zinc alkaline battery according to one embodiment of the present invention will be described below with reference to the drawings.

A brass material having an alloy number of 2700 from the range based on JIS H 3260 was work-hardened into a drawn wire having a diameter of 1.5 mm to obtain a drawn wire having a Vickers hardness shown in (Table 1).

[0019]

[Table 1]

Using the current-collecting rod thus obtained as a negative electrode current collector, an alkaline manganese battery LR6 shown in FIG.
Was assembled. As shown in FIG. 1, mercury-free zinc alloy powder is dispersed together with a gelling agent in an alkaline electrolyte solution in which zinc oxide is dissolved inside a positive electrode mixture 1 formed by adding graphite as a conductive material to manganese dioxide. Gelled zinc negative electrode 2
Is disposed with the separator 3 interposed therebetween, and the negative electrode current collecting rod 4 is inserted into the lower center of the negative electrode 2. The positive electrode mixture 1 is connected to the positive electrode terminal cap 5 via the metal case 6 at the upper part. The negative electrode current collector 4 penetrates the resin sealing body 8 and is in contact with the bottom plate 9.
The positive electrode terminal cap 5 and the bottom plate 9 are sealed by an outer can 7.

As shown in Table 1, Vickers hardness 1
Using a current collecting rod having 20 to 230, 100 batteries were manufactured, and a partial discharge was performed under a temperature condition of 20 ° C. with a constant resistance of 1Ω and a discharge duration of up to 25% of a discharge duration up to a final voltage of 0.9 V. After storing the batteries at 60 ° C. for 2 months, the number of leaked batteries (visual judgment) was counted and shown in Table 1 (Table 1). In addition, 10,000 batteries each using a current-collecting rod having Vickers hardness shown in Table 1 were produced, and the open-circuit voltages of the batteries were measured immediately after the production and after the batteries were stored at 20 ° C. for 3 months. (Table 1) shows the number of batteries having an average value of −20 mV or less as an index indicating the degree of variation.

According to the results shown in Table 1, the battery of this example does not leak at all when a current collector rod having a Vickers hardness of 150 or more is used even after storage at 60 ° C. for 2 months, and has a practical leak resistance. Was secured. However, in a battery having a Vickers hardness of 150 or less, liquid leakage occurs. This is Vickers hardness 1
It is considered that when the value is 50 or less, the current collecting rod comes into contact with or collides with the assembling equipment and other parts in the current collecting rod manufacturing process and the battery assembling process, so that the fine powder such as iron or nickel is easily fixed to the surface.

Regarding the open-circuit voltage of the battery, the number of the batteries having an average value of −20 mV or less in the initial stage is 0,
When stored at 20 ° C. for 3 months, in the case of a battery using a current collecting rod having a Vickers hardness of 150 or less, a battery having an average value of −20 mV or less appears, and the variation in battery voltage increases. Clearly, the variation is small, indicating that the product quality is stable.

From the above, the Vickers hardness of the current collecting rod needs to be 150 or more. The leakage of the battery and the variation in voltage after storage are caused by impurities such as iron and nickel adhering to the surface of the negative electrode current collector rod, causing gas generation and promoting self-consumption of the battery. Conceivable.

[0025]

As is apparent from the above description of the embodiment, according to the present invention, even when a zinc alloy powder containing no mercury is used as a negative electrode active material of an alkaline battery, generation of hydrogen gas is suppressed and corrosion resistance is reduced. Thus, it is possible to improve the liquid leakage resistance, reduce variations in battery performance, and stabilize product quality.

[Brief description of the drawings]

FIG. 1 shows an alkaline manganese battery LR according to one embodiment of the present invention.
Sectional drawing which shows the structure of 6

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode mixture 2 Negative electrode 3 Separator 4 Negative electrode collector 5 Positive electrode terminal cap 6 Metal case 7 Outer can 8 Resin sealing body 9 Bottom plate

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Inoue 1006 Kazuma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A 64-59769 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) H01M 4/66 H01M 4/75

Claims (1)

(57) [Claims] 1. A negative electrode mainly composed of a zinc alloy powder containing no mercury as a negative electrode active material and provided in a central portion of a battery.
A positive electrode provided with a separator on the outer periphery of the negative electrode, and an alkaline battery including a current collecting rod made of copper or a copper alloy inserted as a current collector in the negative electrode, and has a Vickers hardness of 150 as the current collecting rod. A zinc-alkaline battery using a copper or copper alloy wire having a lower limit hardness.