JPH05303978A - Sealed nickel-zinc battery - Google Patents

Abstract

PURPOSE:To prevent the leak of an electrolyte from a battery jar or the reduction of the moisture in the electrolyte, and provide a sealed nickel-lead battery having excellent life performance. CONSTITUTION:A sealed nickel-lead battery has an electrode plate group 5 and a liquid holding layer 6. The electrode plate group 5 has a positive electrode plate 1, a negative electrode plate 4, a separator 2, and a retainer 2. The liquid holding layer 6 has an electrolyte contained in a cellulose fiber 0.5-50mm in length and 5-100mum in diameter, and the liquid holding layer 6 is arranged around the electrode plate group 5. The cellulose fiber may be changed to a porous spherical cellulose fiber 0.1-7mum in diameter or an organic fiber 0.5-50mm in length and 5-100mum in diameter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved sealed nickel-zinc battery.

[0002]

2. Description of the Related Art In recent years, there has been a great demand for higher energy density or higher performance of batteries in electric vehicles and portable devices. Among them, the battery using zinc as the negative electrode active material has an advantage that it has a large energy density per unit weight and is inexpensive. On the other hand, when the zinc electrode is operated as the negative electrode of a storage battery, the zinc active material is dissolved and deposited during the discharging process or the charging process, causing problems such as so-called shape change and dendrite short circuit.

During the charging process, zinc metal crystals deposited from zincate ions are apt to become dendrite crystals due to the catalytic action of hydrogen, especially when accompanied by the generation of hydrogen gas, which causes a battery short circuit. For this reason, the capacity of the negative electrode is increased from that of the positive electrode so that hydrogen will not be generated from the negative electrode even at the end of charging, and the oxygen gas is preferentially generated from the positive electrode even at the end of charging by charging the battery. In the entire charging process, hydrogen gas is not generated from the negative electrode due to electrochemical decomposition of water, and dendrite-like deposition is not generated. In addition, when the above battery is charged and discharged and used as a secondary battery in a cycle, if oxygen generated from the positive electrode leaks out of the system of the battery, the capacity balance between the positive electrode and the negative electrode is disturbed, and eventually the hydrogen from the negative electrode is lost. It is generated, and the dendrite of zinc is deposited to extend the battery life. Therefore, in order to maintain the capacity balance between the positive electrode and the negative electrode during cycle use, there is a sealed nickel-zinc battery in which the amount of electrolytic solution of the battery is limited and oxygen gas generated at the end of charging is absorbed and recycled by the negative electrode.

In addition, especially for stationary use, for electric vehicles, etc., the battery capacity is larger than that for portable use, the electrode plate height becomes higher, and accordingly, the electrolyte retaining property tends to deteriorate. .. When the electrolytic solution cannot be sufficiently retained, the zinc electrode plate is covered with the overflowing electrolytic solution, and the area effective for absorbing oxygen gas cannot be maintained, the oxygen gas absorbing capacity becomes insufficient, and dendrite short circuit is caused. Therefore, the amount of electrolyte to be added must be reduced especially as the capacity of the battery increases.

Further, as described above, when the amount of the electrolytic solution of the battery is limited and the battery is hermetically sealed, it is effective in preventing zinc dendrite short circuit, but it causes zinc shape change. Therefore, in such a case, the cause of the life of the sealed nickel-zinc battery is not the short circuit but the shape change. Further, this shape change is closely related to the amount of electrolyte in the battery, and as the amount of electrolyte is reduced in order to improve the oxygen gas absorption efficiency, the capacity decrease is accelerated and the life of the battery is shortened. That is, as long as it is limited to shape change, the larger the amount of electrolytic solution, the better, but as described above, especially when the amount of electrolytic solution is large, the electrolytic solution that is not retained in the pole group exists in a free state, As mentioned above, the electrolyte in the free state overflows onto the surface of the retainer, separator or zinc electrode and covers the surface, which impedes the permeability of oxygen gas and reduces the oxygen gas absorption capacity of the battery, resulting in dendrite short circuit. Therefore, the amount of electrolyte in the conventional standard sealed nickel-zinc battery is approximately 98% of the total voids in the pole group in order to keep these two elements in appropriate ranges.
It is set below.

[0006]

Since the sealed nickel-zinc battery as described in the prior art has a limited amount of electrolytic solution, even a small amount of electrolytic solution leaking from the electrode plate is leaked to the outside of the battery case. When liquid is used, there are problems that the capacity and life will be extremely reduced and that peripheral devices will be corroded, and water will evaporate during long-time use or water will be generated due to self-discharge of the negative electrode. There is a problem in that it is consumed, the internal resistance increases, and it becomes difficult to discharge.

The present invention has been made in view of the above problems, and an object of the present invention is to prevent the electrolytic solution from leaking from the inside of a battery case and to reduce the water content of the electrolytic solution.
An object is to provide a sealed nickel-zinc battery with excellent life performance.

[0008]

In order to solve the above problems, the present invention relates to a sealed nickel-zinc battery having an electrode plate group 5 and a liquid retaining layer 6, wherein the electrode plate group 5 is , Positive electrode plate 1, negative electrode plate 4, separator 3, and retainer 2, and the liquid retaining layer 6 has a length of 0.5 to 50 m.
m, the electrolytic solution is contained in cellulose fibers having a diameter of 5 to 100 μm, and the liquid retaining layer 6 is arranged around the electrode plate group 5. In addition,
The cellulose fibers are porous spherical cellulose fibers having a diameter of 0.1 to 7 μm or a length of 0.5 to 50 mm and a diameter of 5
It may be replaced with an organic fiber having a thickness of 100 μm.

[0009]

Since the liquid retaining layer is arranged around the electrode plate group, the electrolytic solution leaking from the electrode plate group is scattered by the liquid retaining layer and hardly leaks to the outside. Further, even when the water content of the electrolytic solution with which the electrode plate group is impregnated is consumed, the water content can be supplemented from the liquid retaining layer.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the sealed nickel-zinc battery of the present invention, 1 is a positive electrode plate made of a sintered nickel electrode plate, 2 is a retainer, the material thereof is a polyolefin-based non-woven fabric, 3 is a polypropylene porous film and a surfactant. Treated separator, 4
Is a negative electrode plate in which metallic zinc powder and zinc oxide powder are mixed with polytetrafluoroethylene resin and rolled into a sheet, and the sheet is pressed onto a copper or silver current collector. This is an electrode plate group in which five plates 1 and six negative plates 4 are alternately arranged, and the retainer 2, the separator 3, and the retainer 2 laminated in this order are inserted between them. Reference numeral 6 is a liquid-retaining layer in which a length of 6 mm and a diameter of 25 μm of cellulose fibers or organic fibers, which are arranged in close contact with the upper and side portions of the electrode plate group 5, are impregnated with an electrolytic solution. Reference numeral 7 is a positive electrode terminal that connects the positive electrode plates 1 to each other, and 8 is a negative electrode terminal that connects the negative electrode plates 4 to each other. 9 is a liquid retaining layer 6 on the upper side of the electrode plate group 5
Is an inner lid that closely contacts the electrode plate group 5, and 10 is an ABS battery case that houses the electrode plate group 5, the liquid retaining layer 6, the terminals 7 and 8, and the inner lid 9.

The electrolytic solution is an aqueous solution mainly composed of potassium hydroxide having a specific gravity of about 1.30 to 1.40, and its amount is
An amount corresponding to 90 to 98% of the total void volume of the electrode plate group 5 and the liquid retaining layer 6 is injected into each.

A battery of the present invention of 10 Ah having such a structure was produced, and a conventional battery in which the liquid retaining layer 6 was not arranged around the electrode plate group 5 was used for an electric brush cutter.
The electrolyte leakage rate and cycle characteristics at every 0,300 cycles were investigated. The results are shown in Table 1 and FIG. The leakage rate A is A = (ab) / a, where a is the initial electrode plate group weight in the 100% charged state and b is the 100% charged state electrode plate group after each cycle. × 100 (%), the charge was 0.1 c, and the discharge was 1 c on average.

[0013]

From these results, the product of the present invention is
It was found that the liquid leakage rate was small and the cycle characteristics were excellent. Next, the length α was changed with the diameter β of the cellulose fiber and the organic fiber used in the liquid retaining layer 6 as a parameter, and the number of cycles until the volume decreased to 60% of the initial capacity was investigated. The result is shown in FIG.

From this result, the length α is 0.5 to 50 m.
When m and the diameter β are 5 to 100 μm, the number of cycles is significantly superior to the number of cycles (150 cycles) of the conventional product shown in FIG.

Further, the cellulose fibers used in the liquid retaining layer 6 were replaced with porous spherical ones, and it was investigated how the cycle number changes if the diameter γ of the spheres changes.
The result is shown in FIG. From this result, the diameter γ is 0.1
In the range of 7 mm, it is about 155 cycles or more, which is extremely superior to the conventional product, but if it is less than 0.1 or more than 7 mm, it is almost the same as the conventional product.

[0017]

Since the present invention is configured as described above, it has the following effects. (1) Even if the electrolytic solution leaks or the water content decreases during use of the battery, the electrolytic solution rarely leaks from the electrode group or the water content does not decrease. A sealed nickel-zinc storage battery is obtained. (2) The retention of the electrolytic solution can be enhanced by specifying the fibers constituting the liquid retaining layer, and a sealed nickel-zinc battery having excellent cycle performance can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cycle characteristic diagram comparing the life performances of the product of the present invention and the conventional product.

FIG. 3 is a characteristic diagram showing the number of cycles when the length and diameter of the fibers of the liquid retaining layer are changed.

FIG. 4 is a characteristic diagram showing the number of cycles when the diameter of a porous spherical cellulose fiber is changed.

[Explanation of symbols]

 1 Positive Electrode Plate 2 Retainer 3 Separator 4 Negative Electrode Plate 5 Electrode Plate Group 6 Liquid Retaining Layer

Claims (3)

[Claims] 1. A sealed nickel-zinc battery having an electrode plate group (5) and a liquid retaining layer (6), wherein the electrode plate group (5) comprises a positive electrode plate (1) and a negative electrode plate (1). 4)
And a separator (3) and a retainer (2). The liquid retaining layer (6) has a length of 0.5 to 50 mm and a diameter of 5 to 5.
A sealed nickel-zinc battery, characterized in that the electrolyte solution is contained in 100 μm cellulose fibers, and the liquid retaining layer (6) is arranged around the electrode plate group (5). 2. The sealed nickel-zinc battery according to claim 1, wherein organic fibers are used instead of the cellulose fibers. 3. The cellulose fiber has a diameter of 0.1 to 7
The sealed nickel-zinc battery according to claim 1, which is a porous spherical cellulose fiber having a diameter of mm.