JPH06267587A - Sealed alkali-zinc secondary battery - Google Patents

Abstract

PURPOSE:To provide a sealed alkali-zinc secondary battery whose charging/ discharging cyclic life can be lengthened. CONSTITUTION:Each negative plate 1 containing oxygen depresant, and each positive plate 2 are housed in a battery jar 7 while being enclosed by liquid hold layers 4 and separators 3 in such a way that negative plates 11 and 12 are positioned at the outermost sections, and each zinc electrode 8 which the zinc content against zinc oxide is higher than that of each negative plate 1 is interposed between each negative plate 11 and 12 at the aforesaid outermost sections and the inner wall of the battery jar 7. Therefore, this constitution thereby enables oxygen generated out of the positive electrode at the end of charging and at the time of overcharging to be efficiently led to the entire single surface of each zinc electrode, and also enables oxygen around the periphery of each negative plate to be restrained from being absorbed, the charging/ discharging cyclic life of the battery can thereby be lengthened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed alkaline zinc secondary battery, and more particularly to a laminated structure of its electrode plate, separator and liquid retaining layer.

[0002]

2. Description of the Related Art Recently, a sealed alkaline zinc secondary battery, which is lightweight and easy to maintain, has been attracting attention as a power source for electronic devices and various portable and stationary devices.

In such a sealed alkaline zinc secondary battery, it is necessary to absorb oxygen emitted from the positive electrode at the end of charging or overcharge at the negative electrode, so that the amount of the electrolytic solution is limited, and the electrolytic solution is separated from the separator or the protective solution. It is held in a liquid layer.

As described above, when oxygen is absorbed in the negative electrode, the reduction of zinc oxide in the negative electrode can be suppressed, and the occurrence of penetrating short circuit in the separator and the liquid retaining layer due to the growth of zinc dendrites during charging, It is possible to suppress the decrease in the utilization rate of the negative electrode active material due to the shape change.

A conventional example of the above-mentioned conventional sealed alkaline zinc secondary battery will be described with reference to FIG.

In FIG. 2, 1 is a negative electrode plate in which a negative electrode active material mainly containing zinc and zinc oxide is applied to both sides of a current collector made of copper punching metal, and 2 is the same size as the negative electrode plate 1,
A positive electrode plate made of nickel-metal hydride mainly composed of nickel hydroxide. The negative electrode plate 1 has a liquid retaining layer 4 made of nylon nonwoven fabric or polypropylene nonwoven fabric on the inside and a separator 3 made of a microporous film on the outside. The positive electrode plate 2 is surrounded by the same liquid retaining layer 4 and the separator 3 on three sides except the upper side. The negative electrode plate 1 and the positive electrode plate 2 configured as described above are alternately stacked so that the negative electrode plate is located at the outermost part and housed in the battery case 7.

[0007]

Since the zinc electrode as the negative electrode used in the above-mentioned conventional sealed alkaline zinc secondary battery has a high oxygen absorbing ability, most of the generated oxygen is absorbed in the peripheral portion of the negative electrode. As a result, zinc oxide is likely to be present in the peripheral portion of the negative electrode and metallic zinc is present in the central portion of the negative electrode, so that there is a problem that the discharge capacity is lowered in the initial stage of the charge / discharge cycle.

In order to make such uneven absorption of oxygen uniform, a separator having a high oxygen permeability is used, or a water repellent layer is provided around the zinc electrode as a negative electrode,
Providing a groove for oxygen permeation has been proposed, but although it is effective in efficiently guiding oxygen to the negative electrode, it has not yet been possible to make uneven absorption of oxygen by the negative electrode uniform.

On the other hand, Japanese Patent Application No. 4-300535 discloses an attempt to introduce oxygen to a zinc electrode disposed between the outermost negative electrode plate and the inner wall of the battery case. Oxygen is now absorbed by the zinc electrode as the negative electrode, and there is a problem that the discharge capacity decreases with the progress of the charge / discharge cycle.

[0010]

In order to solve the above problems, the present invention provides a positive electrode plate surrounded by a liquid retaining layer and a separator, an oxygen absorption inhibitor and at least one of zinc and zinc oxide. In a sealed alkaline zinc secondary battery mainly composed of a negative electrode plate surrounded by a liquid-retaining layer and a separator, alternately stacked, and housed in a battery case so that the negative electrode plate is located at the outermost part, At least one of zinc and zinc oxide is the main component between the outermost negative electrode plate and the inner wall of the battery case, and a zinc electrode having a higher zinc content relative to zinc oxide than the negative electrode plate is arranged. .

[0011]

[Operation] Therefore, according to the present invention, the negative electrode plate facing the positive electrode plate is surrounded by the liquid-retaining layer and the separator to reduce its oxygen absorption capacity, and the outermost negative electrode plate and the inner wall of the battery case are provided. The zinc electrode disposed between the two is made to have a higher content of zinc relative to zinc oxide than the negative electrode plate, and the oxygen generated on one side of the zinc electrode is guided, so that the absorption capacity of oxygen is not reduced and charging is performed. The uniformity of the negative electrode plate that contributes to discharge can be maintained.

Further, according to the present invention, the absorption of oxygen in the peripheral portion of the negative electrode plate can be suppressed by including the oxygen absorption inhibitor in the negative electrode plate.

[0013]

EXAMPLE FIG. 1 is a sectional view of a sealed alkaline zinc secondary battery of the present invention.

In FIG. 1, reference numeral 1 denotes a negative electrode plate in which zinc and zinc oxide are the main components, and a negative electrode active material containing tin oxide as an oxygen absorption inhibitor is applied to both sides of a copper punching metal current collector. Is a positive electrode plate having the same size as that of the negative electrode plate 1 and made of a nickel-based combustion-type nitrite. The separator 3 made of a porous film is surrounded on all sides, and the positive electrode plate 2 is surrounded by the same liquid retaining layer 4 and the separator 3 on all sides except the upper side.

The negative electrode plate 1 and the positive electrode plate 2 are alternately stacked so that the negative electrode plates 11 and 12 are located on the outermost side and housed in the battery case 7. ，
A zinc electrode 8 having at least one of zinc and zinc oxide as a main component and having a higher content ratio of zinc to zinc oxide than the negative electrode plates 1, 11 and 12 is arranged between the anode 12 and the inner wall of the battery case 7.

In the sealed alkaline zinc secondary battery shown in FIG. 1, a separator film 5 made of cellophane or the like is arranged between the outermost negative electrode plates 11 and 12 and the zinc electrode 8 and the zinc electrode 8 is used.
And a water-repellent net spacer 6 between the inner wall of the battery case 7 and
Are arranged.

An aqueous solution of potassium hydroxide having a specific gravity of 1.35, to which lithium hydroxide as an electrolytic solution is added, is placed in a battery case 7 in which the electrode group having the above-mentioned structure is housed. The solution was poured to 80 to 95% to obtain a sealed alkaline zinc secondary battery having a capacity of 10 Ah.

In comparison with the above-mentioned battery A of the present invention, comparative battery B
As the negative electrode plate 1 containing no tin oxide as an oxygen absorption inhibitor, the negative electrode plate 1 has a zinc content relative to zinc oxide.
And a zinc electrode 8 which is the same as the above, and a conventional battery C as shown in FIG.

Next, the present invention battery A and comparative battery B described above
A charge / discharge cycle life test was performed on the conventional battery C and the result is shown in FIG. The test condition is 25
The battery was charged with a current of 0.1 C at a temperature of ° C and then discharged with a current of 0.5 C to 80% of the capacity.

From FIG. 3, the battery A of the present invention and the battery B of the comparison do not have a reduced discharge capacity at the beginning of the charging / discharging cycle, and the battery A of the present invention has a life of about 300 cycles and the battery B of the comparison has a life of about 200 cycles. I understood it. On the other hand, it was found that the discharge capacity of the conventional battery C decreased from the beginning of the charge / discharge cycle and reached the end of its life at about 120 cycles.

FIG. 4 shows the results of measurement of changes in oxygen absorption efficiency during the above charge / discharge cycle life test by changes in the weight of the battery.

From FIG. 4, the oxygen absorption efficiency of the conventional battery C was about 90% throughout the charge / discharge cycle life test, whereas the battery A of the present invention and the comparative battery B were almost 100% up to around 100 cycles. It was about. However, it was found that the comparative battery B gradually decreased in oxygen absorption efficiency after 100 cycles and reached about 90% at the end of its life.

In the battery A of the present invention and the battery B of the prior art, oxygen generated from the positive electrode at the end of charging or overcharging is introduced to the entire one surface of the zinc electrode 8 via the net-shaped spacer 6, and the efficiency is uniformly and efficiently. It shows that it is well absorbed, and at the same time, suppresses the absorption of oxygen in the peripheral portion of the negative electrode plate 1 surrounded by the liquid retaining layer 4 and the separator 3, and It shows that the existence can be prevented from becoming non-uniform.

Further, in the battery A of the present invention, the negative electrode plate 1
Since the oxygen absorption inhibitor is contained therein and the zinc electrode 8 having a higher content ratio of zinc to zinc oxide than the negative electrode plate 1 is used, the above effect can be further enhanced.

[0025]

As described above, according to the battery of the present invention, oxygen can be uniformly and efficiently absorbed by the zinc electrode, so that the charge / discharge cycle life of the sealed alkaline zinc secondary battery is improved. be able to.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view of a conventional sealed alkaline zinc secondary battery.

FIG. 3 is a diagram showing the results of a charge / discharge cycle life test.

FIG. 4 is a diagram showing changes in oxygen absorption efficiency by a negative electrode plate during a charge / discharge cycle life test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Negative electrode plate 2 Positive electrode plate 3 Separator 4 Liquid retention layer 5 Separation film 6 Net spacer 7 Battery case 8 Zinc electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Bogauchi Takehito 6-6 Josaimachi, Takatsuki City, Osaka Prefecture Yuasa Corporation

Claims (4)

[Claims] 1. A positive electrode plate surrounded by a liquid retaining layer and a separator, and a negative electrode plate containing an oxygen absorption inhibitor and containing at least one of zinc and zinc oxide as a main component and surrounded by the liquid retaining layer and a separator. Alternately stacked, and in a sealed alkaline zinc secondary battery which is housed in a battery case so that the negative electrode plate is located on the outermost side, between the outermost negative electrode plate and the inner wall of the battery case, zinc Alternatively, a sealed alkaline zinc secondary battery is characterized in that a zinc electrode having at least one of zinc oxide as a main component and having a higher content ratio of zinc to zinc oxide than the negative electrode plate is arranged. 2. The sealed alkaline zinc secondary battery according to claim 1, wherein the oxygen absorption inhibitor is tin oxide. 3. A separator is arranged between the outermost negative electrode plate and the zinc electrode, and / or a water-repellent net-like spacer is arranged between the zinc electrode and the inner wall of the battery case. The sealed alkaline zinc secondary battery according to claim 1 or 2. 4. The positive electrode plate is surrounded by a liquid-retaining layer and a separator on three sides except the upper side, and the negative electrode plate is surrounded on four sides, and the positive electrode plate is surrounded by four sides.
The sealed alkaline zinc secondary battery according to the item.