JPH0689719A - Sealed type nickel zinc storage battery - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the charge / discharge cycle life of sealed nickel-zinc storage batteries. [Structure] An electrode group consisting of a zinc negative electrode, a nickel positive electrode, and a separator, and the zinc negative electrode is covered with an alkali-resistant, non-conductive sheet having fine pores. [Effect] Since the zincate ions are moved only through the micropores, the progress of the shape change of the zinc electrode can be suppressed, the deterioration of the function of the separator can be suppressed, and the charge / discharge cycle life can be shortened. It is possible to improve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed nickel-zinc storage battery, and more particularly to a sealed nickel-zinc storage battery capable of improving charge / discharge cycle life characteristics.

[0002]

2. Description of the Related Art Due to the rapid spread of electronic equipment, the demand for rechargeable secondary batteries is increasing. Such secondary batteries are required to have high energy density due to the downsizing and weight reduction of equipment.

As a secondary battery that meets the above demands, a sealed nickel-zinc storage battery has been receiving attention in recent years.

In such a sealed nickel-zinc storage battery, a separator is provided with a liquid retaining layer impregnated with an electrolytic solution, and zincate ions dissolved in the electrolytic solution move through the liquid retaining layer. .

[0005]

In the sealed nickel-zinc storage battery as described above, the dendrite of zinc grows during charging to cause a short circuit through the separator, or the shape change of the zinc electrode due to the movement of zincate ions. There is a problem that it causes the above phenomenon and shortens the charge / discharge cycle life.

Further, since the entire surface of the zinc negative electrode comes into contact with the separator and the liquid retaining layer, there is a problem that the function of the separator is deteriorated.

[0007]

In order to solve the above problems, the present invention provides a zinc negative electrode containing zinc oxide and metallic zinc as a main component, a nickel positive electrode, and a zinc negative electrode and a nickel positive electrode. In a sealed nickel-zinc storage battery having a pole group consisting of a separator impregnated with an electrolytic solution, the zinc negative electrode is characterized by being encapsulated with an alkali-resistant, non-conductive sheet having micropores. .

[0008]

[Operation] Therefore, in the present invention, since the zinc negative electrode is covered with the alkali-resistant, non-conductive sheet having micropores, the movement of zincate ions can be regulated, and the shape change of the zinc electrode can be suppressed. The progress can be suppressed.

Further, since the zinc negative electrode comes into contact with the separator and the liquid retaining layer only through the fine pores, it is possible to suppress the deterioration of the function of the separator.

In the sealed nickel-zinc storage battery of the present invention, the reaction during charging occurs near the current collector inside the zinc negative electrode, and the gas absorption by the zinc negative electrode occurs near the surface of the zinc negative electrode through the micropores. Therefore, the zinc dendrite does not grow through the micropores.

[0011]

1 is a sectional view of a sealed nickel-zinc storage battery of the present invention.

In FIG. 1, 1 is a sinter-type nickel positive electrode, 2 is a separator having a liquid-retaining layer, 3 is a paste-type zinc negative electrode, and the nickel positive electrode 1 comprises 3 sheets and the zinc negative electrode 3 comprises 4 sheets. It is arranged so as to enclose the nickel positive electrode. Reference numeral 4 denotes a polypropylene sheet as an alkali-resistant, non-conductive sheet having micropores according to the present invention, which is arranged so as to enclose the zinc negative electrode 3 and to be interposed between the zinc negative electrode 3 and the separator 2. There is.

The polypropylene sheet 4 as the alkali-resistant and non-conductive sheet has fine holes 41 as shown in the perspective view of the essential part of the zinc negative electrode 3 in FIG. In FIG. 2, 31 is a paste-like negative electrode active material mainly containing zinc oxide and metallic zinc, and 32 is a negative electrode current collector made of a copper punching plate.

The above-mentioned pole group is housed in a battery case 5, and an aqueous potassium hydroxide solution having a specific gravity of 1.3 to 1.4 as an electrolytic solution is injected and sealed.

Next, the sealed nickel-zinc storage battery A of the present invention and the conventional sealed nickel-zinc storage battery B having no polypropylene sheet 4 are discharged at a discharge current of 1.4 A to a discharge depth of 100%. After that, a charge / discharge cycle test in which the battery was charged to 105% of the nominal capacity with a charging current of 0.7 A, and the result is shown in FIG.

From FIG. 3, the conventional sealed nickel-zinc storage battery B has a discharge capacity of 120% reduced to 60% of the initial capacity, while the sealed nickel-zinc storage battery A of the present invention has a discharge capacity of the initial capacity. It is 20 that fell to 60% of
It can be seen that 0 cycles have elapsed.

Next, the change of the initial capacity of the battery of the present invention was investigated by changing the aperture ratio of the polypropylene sheet 4 having a pore diameter of 1 mm, and the result is shown in FIG.

From FIG. 4, when the opening ratio of the polypropylene sheet 4 is 30% to 80%, the initial capacity is almost 100%.
It turns out that

Next, the charge / discharge cycle life characteristics of the battery of the present invention were investigated by changing the aperture ratio of the polypropylene sheet 4 having a pore diameter of 1 mm, and the results are shown in FIG.

From FIG. 5, when the opening ratio of the polypropylene sheet 4 is 30% to 70%, the charge / discharge cycle life is 1.
It turns out that it becomes 50 cycles or more.

Next, the pore diameter of the polypropylene sheet 4 was changed in the range of 0.2 mm to 4.0 mm so that the opening ratio would be 50%, and the charge / discharge cycle life characteristics of the battery of the present invention were investigated. As shown in FIG.

From FIG. 6, it can be seen that when the polypropylene sheet 4 has a pore size of 0.5 mm or more and 3.0 mm or less, the charging / discharging cycle life is close to 200 cycles.

From the above, the polypropylene sheet 4 in the battery of the present invention has an opening ratio of fine pores of 30% to 70%.
%, It is understood that the average pore diameter may be 0.5 mm or more and 3.0 mm or less.

[0024]

As described above, the sealed nickel-zinc storage battery of the present invention can improve its charge / discharge cycle life.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a sealed nickel-zinc storage battery of the present invention.

FIG. 2 is a perspective view of a zinc negative electrode plate used in the sealed nickel-zinc storage battery of the present invention.

FIG. 3 is a diagram comparing charge and discharge cycle lives.

FIG. 4 is a diagram showing the relationship between the aperture ratio and the initial capacity of an alkali-resistant, non-conductive sheet.

FIG. 5 is a diagram showing the relationship between the aperture ratio of an alkali-resistant, non-conductive sheet and the charge / discharge cycle life.

FIG. 6 is a diagram showing the relationship between the pore size of an alkali-resistant and non-conductive sheet and the charge / discharge cycle life.

[Explanation of symbols]

 1 Nickel positive electrode 2 Separator 3 Zinc negative electrode 4 Polypropylene sheet 5 Battery case

Claims (3)

[Claims] 1. A pole group comprising a zinc negative electrode mainly composed of zinc oxide and metallic zinc, a nickel positive electrode, and a separator which is interposed between the zinc negative electrode and the nickel positive electrode and impregnated with an electrolytic solution. A sealed nickel-zinc storage battery, characterized in that the zinc negative electrode is covered with an alkali-resistant, non-conductive sheet having micropores. 2. The sealed nickel-zinc storage battery according to claim 1, wherein the aperture ratio of the fine holes of the alkali-resistant, non-conductive sheet is 30% to 70%. 3. The sealed nickel-zinc storage battery according to claim 1, wherein the average pore diameter of the micropores of the alkali-resistant, non-conductive sheet is 0.5 mm or more and 3.0 mm or less.