JP3350359B2 - Manufacturing method of positive electrode plate for alkaline storage battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkaline storage battery, and more particularly to a method for manufacturing a positive electrode plate thereof.

[0002]

2. Description of the Related Art For a positive electrode plate of an alkaline storage battery such as a nickel-cadmium storage battery and a nickel-hydrogen storage battery, a metal porous body such as a foamed metal substrate, a metal fiber substrate, or a punching metal is used as a support, and a hydroxide is formed thereon. A mixture containing an active material such as nickel is filled and used. Such a positive electrode plate 1
After continuously filling the voids of a long metal porous body 1a used as a support with an active material mixture, the metal porous body 1a is sheared to a predetermined size by a cutter 2 as shown in FIG. It is made.

However, when the metal porous body is sheared, as shown in FIG. 3 (c), a burr 3 protrudes from the end of the shearing surface of the positive electrode plate 1, and the assembled alkaline storage battery has this problem. Caused a short circuit. In particular, this phenomenon appears remarkably when a foamed metal substrate is used for the support.

A group of electrode plates in which a positive electrode plate and a negative electrode plate are alternately stacked with a separator interposed therebetween is arranged in a state where a constant pressure is applied in the stacking direction of the positive electrode plates when inserted into a battery case. When assembling an alkaline storage battery using such a positive electrode plate, the separator disposed opposite to the positive electrode plate,
A large pressure is locally applied to the portion where the burr comes into contact. As a result, the separator locally deteriorates, causing a short circuit between the electrode plates.

To solve this problem, Japanese Patent Laid-Open Publication No.
No. 0 discloses a method of making the thickness of the peripheral portion of the positive electrode plate smaller than the thickness of the central portion. In this report, it was reported that the short-circuit occurrence rate, which was about 5% in the conventional method, was reduced to about 3% by making the thickness of the end portion of the positive electrode plate 0.01 mm thinner than the thickness of the central portion. Have been. But,
This value is not sufficient, and it is required to further reduce the short-circuit occurrence rate.

[0006]

SUMMARY OF THE INVENTION The present invention provides a highly reliable positive electrode plate for an alkaline storage battery capable of suppressing a short circuit between the positive electrode and the negative electrode due to a burr generated at the end of the shearing surface of the positive electrode plate. The purpose is to provide.

[0007]

According to the method for producing a positive electrode plate for an alkaline storage battery of the present invention, the end face of the positive electrode plate on which burrs are generated by shearing is formed with a chamfer width of 0.5 or more relative to the thickness of a separator used . In addition, chamfering is performed by polishing at a chamfer angle of 30 to 60 degrees . This makes it possible to remove burrs extending in the thickness direction of the positive electrode plate, or to shorten the length of the positive electrode plate in the thickness direction even if the burrs cannot be completely removed. In addition, a short circuit with the negative electrode plate can be suppressed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a positive electrode plate for an alkaline storage battery according to the present invention comprises the steps of: filling a sheet-like porous metal body with an active material mixture; shearing the porous metal body to a predetermined size; The burrs of the sheared surface of the metal porous body have a chamfer width of 0.5 or more relative to the thickness of the separator used by being laminated on the electrode plate , and a chamfer angle of 30 to 60.
And a step of removing by polishing. Preparation of other alkaline storage battery positive electrode plate of the present invention includes the steps of shearing a sheet-like metallic porous body into a predetermined size, a step of filling an active material mixture to the metallic porous body, the metallic porous the generated ends of the burr of shear plane of the body, 0.5 or more faces in a ratio to the thickness of the separator used to laminate the plates
It includes a step of polishing and removing at a chamfer width and a chamfer angle of 30 to 60 degrees .

[0009]

Embodiments of the present invention will be described below in detail. Nickel hydroxide powder and cobalt hydroxide powder in a weight ratio of 10
After mixing at 0:10, water was added to the mixed powder to form a paste. This paste is used as a support for a thickness of 1.
Filled into a 5 mm foamed nickel substrate. Next, the foamed nickel substrate was dried and molded under pressure, and then immersed in an aqueous dispersion of polytetrafluoroethylene powder. Thereafter, it is dried again, and the width is 90 mm and the length is 70 mm.
To obtain a positive electrode plate.

The end of the shear surface 6 of the obtained positive electrode plate 1 is
Polishing was performed with a grinder 4 shown in FIG.
The grinder 4 is made of stainless steel, and has a cylindrical shaft portion 4a and a cylindrical portion 4b having the same shaft as the shaft portions 4a arranged at both ends.
And a conical tapered portion 4c between the shaft portion 4a and the cylindrical portion 4b, the surface of which is polished with diamond. The grinder 4 rotates about this axis, and the tapered portion 4c
The edge of the sheared surface 6 of the positive electrode plate 1 where the burrs 3 are generated is polished. In the drawings, the vertical direction is the thickness direction of the positive electrode plate 1. As described above, the flat polished surface 5 was formed at the end of the shear surface 6 as shown in FIG. The chamfer angle β was fixed at 45 degrees, and the chamfer width α was varied.

On the other hand, a slurry was prepared by mixing hydrogen storage alloy powder, carbon powder as a conductive material, and carboxymethylcellulose and styrene-butadiene rubber as binders and dispersing them in water. This slurry was applied to a punching metal, dried, and then rolled with a roller to a width of 90 m.
m and a length of 70 mm were sheared to obtain a negative electrode plate.

[0012] Lead pieces are respectively connected to the ten positive electrode plates and eleven negative electrode plates thus obtained, and these are alternately laminated with a 0.2 mm-thick polypropylene non-woven fabric interposed therebetween as a separator. And inserted into the battery case.
Next, an aqueous solution of potassium hydroxide having a specific gravity of 1.30 was injected into the battery case as an electrolytic solution, and the opening of the battery case was closed to produce a unit cell.

[0013] For each of the 1000 single cells having different chamfer widths α of the positive electrode plate, it is assumed that the cells having a voltage of 0.5 V or less after being charged at 0.1 C for 1 hour and left for 10 minutes are short-circuited. And the short circuit occurrence rate was measured. FIG. 4 shows the result. According to this, it is understood that the short-circuit occurrence rate decreases as the chamfer width α increases. In particular,
It can be seen that when the ratio of the chamfer width α to the thickness of the separator is 0.5 or more, the short-circuit occurrence rate is almost constant at 0.6% and shows an excellent value.

Next, the chamfer angle β was examined.
Here, the ratio of the chamfer width α to the separator thickness is 0.6
, And 1000 single cells each using a positive electrode plate having a chamfer angle β of 10 to 80 degrees were prepared, and the short-circuit occurrence rate was determined in the same manner as described above. The result is shown in FIG. According to this, when the chamfer angle β is in the range of 30 to 60 degrees, the short circuit occurrence rate is almost constant at 0.4 to 0.5% and shows an excellent value .

In the above embodiment, after the support was filled with the active material mixture, the support was sheared to a predetermined size and used for the positive electrode plate.
After the support is sheared to a predetermined size in advance, the support may be filled with the active material mixture. In this case, the degree of burrs at the time of shearing is larger than in the case where the active material mixture is filled first, but the same effect can be obtained by polishing within the range of the chamfer width. Furthermore, although the edge of the shearing surface of the positive electrode plate is chamfered and processed into a flat shape, the same effect can be obtained by processing into a curved shape with an R. The radius of curvature in this case may be in the same range as the above-described chamfer width.

[0016]

According to the present invention, it is possible to suppress a short circuit between the positive electrode and the negative electrode due to burrs at the end of the positive electrode plate. Also,
By using this, a highly reliable alkaline storage battery can be provided.

[Brief description of the drawings]

FIG. 1 is a front view showing a means for polishing a shear surface of a positive electrode plate according to an embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing the positive electrode plate, wherein FIG. 2A is a front view of a main part, and FIG. 2B is a perspective view of the main part.

FIGS. 3A and 3B are front views showing generation of burrs in a shearing step of the positive electrode support, wherein FIG.
(C) shows the state after shearing.

FIG. 4 is a characteristic diagram illustrating a chamfer width of a shear surface of a positive electrode plate and an occurrence rate of a short circuit of an alkaline storage battery using the same according to an example of the present invention.

FIG. 5 is a characteristic diagram illustrating a chamfer angle of a shear surface of a positive electrode plate and a short-circuit occurrence rate of an alkaline storage battery using the same according to an example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode plate 1a Porous metal body 2a Cutter 3 Burr 4 Grinder 4a Shaft part 4b Tube part 4c Tapered part 5 Polished surface 6 Shear surface α Chamfer width β Chamfer angle

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Munehisa Ikoma 1006 Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-6-89717 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01M 4/02-4/04 H01M 4/14-4/34

Claims (2)

(57) [Claims] 1. A step of filling a sheet-shaped porous metal body with an active material mixture, a step of shearing the porous metal body to a predetermined size, and an end of the sheared surface of the porous metal body where burrs are generated. Part, with a chamfer width of 0.5 or more relative to the thickness of the separator used by laminating the electrode plate , and the chamfer angle
A method for producing a positive electrode plate for an alkaline storage battery, comprising a step of removing at 30 to 60 degrees . 2. A step of shearing a sheet-shaped porous metal body to a predetermined size, a step of filling the porous metal body with an active material mixture, and an end of the sheared surface of the porous metal body where burrs are generated. Part, with a chamfer width of 0.5 or more relative to the thickness of the separator used by laminating the electrode plate , and the chamfer angle
A method for producing a positive electrode plate for an alkaline storage battery, comprising a step of polishing and removing at 30 to 60 degrees .