JPH10162816A - Electrode for secondary battery and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent jumping-out of metallic fiber, eliminate leakage failure, and reduce dispersion of a battery characteristic by forming embossments on a base board for an electrode, and forming a crack of an applied layer of paste in a straight line shape along the embossments in a paste type secondary battery using the metallic fiber as a current collecting material. SOLUTION: Embossments 54 juxtaposed in parallel in a straight line shape are formed on at least one surface side of a base board 5a for an electrode, and a paste layer 5b containing metallic fiber as a current collecting material is applied, and a paste applied base board 5 is wound in a spiral shape. Therefore, a straight line-shaped crack is caused along the embossments 54 in the paste layer 5b, and since the metallic fiber does not jump out of such a straight line-shaped crack, leakage failure by projection of the metallic fiber is not caused. Since a crack shape is a straight line shape and is not a zigzag shape, an outer peripheral surface of the electrode becomes smooth, and the occurrence of dispersion in gas pressure at chaging time is reduced, and dispersion of a battery characteristic can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paste type electrode for an alkaline secondary battery containing metal fibers as a current collector, and a method for producing the same.

[0002]

2. Description of the Related Art An electrode group of an alkaline secondary battery is disclosed in
As disclosed in JP-A Nos. 0-10038, 60-130053, and 61-99278, respectively, a negative electrode containing a hydrogen storage alloy and a positive electrode containing nickel oxide are made of synthetic resin fibers. It is partitioned by a separator made of a nonwoven fabric, and is formed by winding these together. As described in the specification of Japanese Patent Application No. 7-26896, the electrode group is spirally wound so that the outermost end is the end of the negative electrode, and the outermost end of the negative electrode is a cylindrical container. It is structured to be in contact with the inner surface. These electrode groups are immersed in a strongly alkaline electrolyte such as a potassium hydroxide solution in a battery container. As shown in FIG. 4, in the nickel-metal hydride secondary battery 1, the sheets 4, 5, 6
Are spirally wound to form a spiral stacked electrode group 3.

[0003]

However, in the conventional secondary battery electrode, as shown in FIG. 6, since the winding curvature is small, the electrode surface of the electrode group 3 which is spirally wound is zigzag. A large number of cracks 7 are formed, and a large number of metal fibers 8 project outward from these cracks 7.
The protruding metal fibers 8 cause a leak failure of the battery,
The battery characteristics vary. In addition, since the crack 7 has a zigzag shape, a smooth bent surface (outer peripheral surface) cannot be obtained, which causes a variation in gas pressure at the time of charging or a variation in battery characteristics.

The present invention has been made to solve the above-mentioned problems, and the metal fibers in the paste do not fly outward even when spirally wound, and have a smooth and good outer peripheral surface.
An object of the present invention is to provide a secondary battery electrode excellent in battery characteristics that does not cause a leak failure and the like, and a method for manufacturing the same.

[0005]

The electrode for a secondary battery according to the present invention is a paste type electrode for a secondary battery containing metal fibers as a current collector, which is arranged substantially linearly in parallel on at least one side. A continuous or discontinuous emboss is formed,
It is characterized by comprising a spirally wound electrode substrate, and a paste containing metal fibers applied as a current collector applied to the embossed surface of the electrode substrate.

The method for manufacturing a secondary battery electrode according to the present invention is the method for manufacturing a paste-type secondary battery electrode including a metal fiber as a current collector, the method comprising: forming a substantially linear electrode on at least one side of the electrode substrate; Forming a continuous or discontinuous embossing arranged in parallel to the substrate, applying a paste containing metal fibers as a current collector to the embossed surface of the electrode substrate, rolling the paste applied substrate, and applying the paste applied substrate In a substantially spiral form in the paste along the embossment by spirally winding the paste.

In the method of manufacturing an electrode for a secondary battery according to the present invention, since the emboss is formed in advance on the electrode substrate before winding, when the spiral is wound, the paste coating layer follows the emboss. Cracks occur almost linearly. Since the metal fibers do not protrude from such linear cracks, no leak failure occurs. Further, since the crack shape is linear and does not become zigzag, the outer peripheral surface of the electrode becomes smoother than before, and the gas pressure during charging does not vary.

[0008]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Figure 1
Several methods for manufacturing the electrode for a secondary battery of the present invention will be described with reference to FIG.

A nickel substrate having a thickness of about 1 mm is used as a material for the electrode substrate. The both surfaces of the nickel substrate 5a are embossed using a special roller having an uneven surface (step S1). As shown in FIGS. 1 and 2, the embosses 54 are arranged linearly and parallel discontinuously in the paste application section 51. Further, the front side emboss 54 and the back side emboss 54 are formed at locations substantially corresponding to each other. In this embodiment, a case will be described in which both surfaces of the substrate 5a are embossed, but only one surface of the substrate 5a may be embossed. Further, the emboss 54 is not limited to the discontinuous linear shape, but may be formed in a continuous linear shape.

The emboss 54 shown in FIG. 2 has a depth of 0.2 to 0.4 mm (optimum of about 0.3 mm) and a width of 0.3 to 1.0 mm (approximately 0.5 mm). It is preferable to set the pitch interval to 2 to 3 mm (optimum is about 2.5 mm).

In a mixed powder consisting of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt monoxide powder, 0.1% of carboxymethyl cellulose was added to nickel hydroxide powder.
3 parts by weight of a suspension of polytetrafluoroethylene (specific gravity 1.5, solid content 60% by weight) is added in an amount of 0.5 part by weight in terms of solid content, and 45 parts by weight of distilled water is added thereto and kneaded. Thus, a paste was prepared. Further, a predetermined amount of the nickel metal fiber 8 is kneaded into the paste, which is applied to the electrode substrate 5a and dried to form the paste layer 5b (step S2).

Next, the paste-coated substrate 5 is rolled by a roller press until the entire thickness becomes 0.40 to 0.65 mm (step S3). Further, the non-paste application section 52
Is joined to a metal tab 53 to obtain a sheet before winding as shown in FIG. Embosses 54 are formed in the paste application section 51 of this sheet at predetermined pitch intervals in a linear intermittent manner and parallel to each other.

Next, the paste-applied substrate 5 is mounted on a winding device, and this is spirally wound together with the positive electrode 6 and the separator 4 (step S4). As shown in FIG. 3, a linear crack 7A was formed on the outer peripheral surface of the electrode group 3 along the embossed portion 54 by the winding process, but no protrusion of the metal fiber 8 was observed.

The electrode group 3 thus obtained was housed in the cylindrical container 2 with a bottom so that the lamination surface thereof was parallel to the depth direction of the container 2. Further, the obtained nickel-hydrogen secondary battery 1 not containing an electrolytic solution is incorporated in a liquid injection device with a distance of 0.5 mm between the upper end of the electrode group of the battery and the lower end of the outlet of the liquid injection member. , The pressure in the container is reduced to 110 Torr,
2.5 cc of an alkaline electrolyte composed of 7N KOH and 1N LiOH was injected into the container while applying a centrifugal force to the container at a rotation speed of 1000 rpm. A lead is attached to the edge of the positive electrode 6, and a tab as a current collector is joined to the lead. The tab 53 is joined to the cap, the tab 53 is bent, the cap is put on the container 2, and the two are joined to obtain the secondary battery 1 (step S).
5).

[0015]

According to the present invention, since the emboss is formed in advance on the electrode substrate before the winding, when the spiral is wound in a spiral shape, the paste coating layer is substantially linearly cracked along the emboss. Is generated. Since the metal fibers do not protrude from such linear cracks, no leak failure occurs.
In addition, since the crack shape is linear and does not become zigzag, the outer peripheral surface of the electrode becomes smoother than before, and the gas pressure during charging does not vary.

[Brief description of the drawings]

FIG. 1 is a plan view showing an electrode sheet before winding.

FIG. 2 is a cross-sectional view of the electrode sheet of the present invention.

FIG. 3 is a perspective view showing a spiral electrode group according to the present invention.

FIG. 4 is an exploded perspective view showing the internal structure of the secondary battery.

FIG. 5 is a process chart showing a method for producing an electrode for a secondary battery of the present invention.

FIG. 6 is a perspective view showing a conventional spiral electrode.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Secondary battery, 3 ... Electrode, 4 ... Separator, 5 ... Paste-applied substrate (negative electrode), 5a ... Substrate, 5b ... Paste layer, 6 ... Positive electrode, 7, 7A ... Cracking, 8 ... Projected metal fiber, 51 ... paste application part, 52 ... non-paste application part, 53 ... tab, 54 ... emboss.

Claims (2)

[Claims] 1. A paste-type secondary battery electrode containing metal fibers as a current collector, wherein a continuous or discontinuous embossment is formed on at least one side of the electrode in a substantially linear and parallel manner, and is spirally wound. An electrode for a secondary battery, comprising: an electrode substrate provided as described above; and a paste containing, as a current collector, metal fibers applied to an embossed surface of the electrode substrate. 2. A method for producing a paste-type secondary battery electrode including a metal fiber as a current collector, wherein a continuous or discontinuous embossment is formed on at least one side of the electrode substrate so as to be substantially straight and parallel. A step of applying a paste containing metal fibers as a current collector to the embossed surface of the electrode substrate; a step of rolling the paste-coated substrate; and a step of spirally winding the paste-coated substrate to form the embossed portion. Producing a substantially linear crack in the paste along the electrode.