JPH0638376Y2 - Alkaline zinc storage battery - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention relates to an alkaline zinc storage battery using a zinc electrode as a negative electrode such as a silver-zinc battery or a nickel-zinc battery. The present invention relates to a cylindrical alkaline zinc storage battery provided with an electrode body that is wound in a spiral shape.

(B) Conventional Technology Zinc as a negative electrode active material has the advantages that it has a large energy density per unit weight and is inexpensive. However,
Zinc dissolves in alkaline electrolyte during discharge and becomes zincate ion, and during charge, zincate ion is deposited on the surface of zinc electrode in dendritic or sponge form. As a result, there is a drawback that an internal short circuit occurs, which results in a short cycle life of the alkaline zinc storage battery.

In order to improve the cycle life, JP-A-55-29548 proposes to regulate the amount of electrolyte solution to prevent the diffusion of zincate ions, which improves the cycle life. However, the deformation of the zinc electrode peripheral portion due to the edge effect and the like could not be sufficiently suppressed even by the above method.

Further, in alkaline storage batteries, the electrode body is generally used in a spiral shape. For example, a separator is interposed between the positive electrode and the negative electrode, and these are spirally wound to form an electrode body, which is disclosed in Japanese Utility Model Publication No. 58-26461. As shown in FIG. 3, an adhesive tape is attached to the outer peripheral surface of the electrode body, fixed so that the winding pressure is maintained, and then housed in a battery outer can to form a battery. However, in the alkaline zinc storage battery, when the electrode body is formed into a spiral shape in this manner, the electrolytic solution is likely to accumulate at the outermost periphery of the electrode body, and therefore, the zinc electrode is particularly likely to be deformed in the above-described peripheral edge portion of the zinc electrode where shape deformation easily occurs. Electric current concentrates on the end of winding, and dendritic zinc grows well. Furthermore, since the end of winding of the zinc electrode receives the strongest pressure toward the center of the electrode body, the edge of the electrode may break the separator, which causes the end of winding of the zinc electrode. An internal short circuit occurred and a sufficient cycle life was not obtained.

(C) Problems to be solved by the present invention The present invention will prevent an internal short circuit at the end of winding of a zinc electrode in an alkaline zinc storage battery having a spiral electrode body and improve cycle life. It is what

(D) Means for Solving the Problems The alkaline zinc storage battery of the present invention is provided with a spiral electrode body, and the winding end end portion of the zinc electrode located on the outer periphery of the electrode body and this winding body. An insulating adhesive tape is interposed between the positive electrode and the positive electrode located on the inner peripheral side of the end portion, and the insulating adhesive tape is wound around the outer peripheral surface of the electrode body.

(E) Action When an insulating adhesive tape is interposed between the winding end end of the zinc electrode located on the outer peripheral portion of the spirally wound electrode body and the positive electrode located on the inner peripheral side of the winding end end, the insulating adhesive tape is formed. The tape relaxes the current concentration at the end of winding of the zinc electrode and makes the current distribution between the zinc electrode and the positive electrode uniform, so that the growth of dendritic zinc from the zinc electrode at this part is Can be suppressed. Further, the insulating adhesive tape interposed between the zinc electrode and the positive electrode can mechanically prevent the edge of the winding end of the zinc electrode from coming into contact with the positive electrode.

(F) Example FIG. 1 is a cross-sectional view of a spirally wound electrode body used in the battery of the present invention, which is constructed as follows. That is, a separator (a) is provided between a zinc electrode (1) having an active material layer containing zinc oxide as a main component formed on both sides of a negative electrode current collector made of punching metal and a known sintered nickel electrode (2). 3) is always interposed so that these three members are spirally wound to form an electrode body, and then the end of winding (5) of the zinc electrode (1) is in contact with the inner circumference side of the electrode body. The polypropylene insulating pressure-sensitive adhesive tape (4) attached to the end of the separator (3) at the position is wound around the outer peripheral surface of the electrode body to be attached, whereby the winding pressure of the electrode body is maintained. ing. The insulating adhesive tape (4) has a width larger than that of the zinc electrode, and the winding end portion (5) of the zinc electrode is covered with the insulating adhesive tape (4).

FIG. 2 is a cross-sectional view of a spirally wound electrode body prepared for comparison, and the same components as those in FIG. 1 are designated by the same reference numerals. This electrode body starts to be wound by sticking one end of a polypropylene insulating adhesive tape (4) to the outer peripheral surface of the electrode body, and the only difference from the electrode body of the battery of the present invention is the winding method of this insulating adhesive tape.

FIG. 3 shows a charge / discharge cycle characteristic diagram when a battery (A) was manufactured using the electrode body of the battery of the present invention and a battery (B) was manufactured using the comparative electrode body and charging and discharging were repeated. As is apparent from the drawings, the battery (A) has a long cycle life and is superior to the battery (B). When the battery was disassembled after the end of the cycle test, internal short-circuit occurred at the end of winding of the zinc electrode in battery (B), whereas the shape at the end of winding of the zinc electrode in battery (A) There was little deformation and no internal short circuit was observed.

In the embodiment, an insulating adhesive tape was placed between the end of winding of the zinc electrode and the separator at the position where the end of winding is in contact with the inner peripheral surface of the electrode body. Suppresses current concentration at the end of winding of the zinc electrode, even if it is placed between the separator that is in contact with the end end on the inner surface side of the electrode body and the positive electrode that is in contact with the separator at this position. At the same time, it is possible to mechanically prevent the edge of the electrode at the end portion from coming into contact with the positive electrode, so that the same effect can be obtained.

(G) Effect of the Invention The alkaline zinc storage battery of the present invention is provided between the winding end end of the zinc electrode located on the outer peripheral portion of the spiral electrode body and the positive electrode located on the inner peripheral side of the winding end end. An insulating adhesive tape having a width larger than that of the zinc electrode is interposed between the electrodes and the insulating adhesive tape is wound around the outer peripheral surface of the electrode body. Conventionally, the insulating adhesive tape is attached to the outer peripheral surface of the electrode body to maintain a winding pressure. The short circuit between the zinc electrode and the positive electrode at the end of winding of the zinc electrode can be prevented by simply changing the width of the insulating adhesive tape and changing the winding method, improving cycle life. Can be made.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an electrode body used in the battery of the present invention, FIG. 2 is a cross-sectional view of an electrode body prepared for comparison, and FIG. 3 is a charge of the battery of the present invention (A) and a comparative battery (B). It is a discharge cycle characteristic view. (1) …… Zinc electrode, (2) …… Nickel electrode, (3) ……
Separator, (4) ... Insulating adhesive tape

Claims (1)

[Scope of utility model registration request] 1. An electrode body comprising a positive electrode and a zinc electrode spirally wound together with a separator interposed between these electrodes, wherein a winding end portion of the zinc electrode is provided on an outer peripheral portion of the electrode body. And an insulating adhesive tape having a width larger than that of the zinc electrode is interposed between the winding end end of the zinc electrode and the positive electrode located on the inner circumference side of the winding end end and the outer periphery of the electrode body. Alkaline zinc storage battery characterized by being wound on the surface.