JPH10247493A - Method for producing battery electrode and alkaline storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the quantitative dispersion of a filled active material and simply and surely form a lead fitting compression section at the prescribed position by applying ultrasonic vibration to a part of a metal porous body filled with an active material kneaded object, removing the kneaded object, pressurizing the portion from both the surface and back face, and providing the lead fitting compression section at the center section of the thickness. SOLUTION: An active material paste is discharged from a nozzle while a belt-like metal porous body is moved, and an active material is filled into the space section of the metal porous body. The prescribed process is applied to the metal porous body filled with the active material paste, then ultrasonic vibration is applied to a part continued to the end edge of the metal porous body to remove the active material, the portion removed with the active material is pressurized from both the surface and back face, and a compression section 3 is provided at the center section of the thickness. The metal porous body is cut so that the compression section 3 is located at the center in the length direction to form an electrode A. The electrode A is constituted of a portion (a) filled with the active material and a portion (b) filled with no active material.

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 an electrode thereof, in which a variation in the amount of an active material to be filled in a space of a porous metal body having a three-dimensionally connected space. While reducing
The lead mounting compression section can be easily and reliably formed at a predetermined position.

[0002]

2. Description of the Related Art As electrodes for alkaline storage batteries, there are pocket type electrodes, sintered type electrodes, and paste type electrodes. In recent years, paste-type electrodes have been adopted, particularly from the viewpoint of increasing the capacity, and as a method for producing the paste-type electrode, a method of filling a paste-like kneaded material into a base made of a sponge-like porous metal body having a space connected in three dimensions is often used. Have been.

[0003] Since this porous metal body has a porosity of 95% and a pore diameter of a space portion as large as several hundred µm, it can be directly filled with a paste-like active material or an active material powder. Electrodes can be manufactured by the construction method. A typical method for producing such a conventional paste-type electrode is, for example, to apply pressure to at least a part of at least one edge of one surface of a band-shaped sponge-like porous metal body having a space connected three-dimensionally. After the compression parts are provided at predetermined intervals, the paste-like kneaded material mainly composed of the active material is formed on both surfaces of the porous metal body while moving the porous metal body while opening the same width as the width of the porous metal body. A method of discharging from a nozzle having a length and filling the inside of the space from both left and right surfaces of the porous body or from one surface to the other surface has been adopted.

[0004] In this case, the compressed portion provided in advance in the sponge-like porous metal body is substantially non-porous due to pressurization, so that the compressed portion is hardly filled with the active material. Then, the electrode is cut into a predetermined size, and one end of a lead piece is spot-welded to the compressed portion to form an electrode.

[0005]

In the above-mentioned paste filling method, a method of filling the paste from one side is provided with a pressurized compression part on a part of one surface of the porous metal body, and the other side is filled from the opposite side. When the active material is filled, the compressed portion serves as a barrier, and the active material to be filled is rebounded and enters the space of the porous body from the cutout of the concave portion facing the compressed portion. In the vicinity of, the filling amount of the active material becomes larger than in other portions apart from the compression portion.

On the other hand, when the active material is filled from the same side as the compressed portion, the compressed material is almost non-porous, so that the active material is directly bounced back, hardly filled, and faces the compressed portion. A part of the filled active material escapes to the outside by being pushed by the filling pressure around the cut portion of the concave portion. As a result, the filling amount of the active material is smaller in the vicinity of the compression part than in other parts.

As described above, the amount of the active material most involved in the discharge capacity of the battery is different from the other portions in the porous portion facing the concave portion near the compression portion connecting one end of the lead. There is a big problem of variation. In particular, there is a problem that the discharge capacity of the battery varies at a low level when the active material filling amount near the compression section is small.

Further, in this method of forming an electrode, the compressed portion is provided in the porous metal body at a predetermined interval before filling with the paste-like kneaded material. The size of the porous metal sponge must be changed, and the production efficiency is very poor.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is to discharge a paste-like kneaded material mainly composed of an active material into a strip-shaped sponge-like porous metal body having a three-dimensionally connected space. After filling the space inside the porous metal body, before or after cutting the porous metal body to a predetermined size,
Ultrasonic vibration is applied to the part connected to the edge of the porous metal body to remove the paste-like kneaded material, and the part is pressed from both front and back surfaces to provide a compression part for attaching lead pieces in the center of the thickness for batteries This is a method for manufacturing an electrode.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION
A method for manufacturing an electrode having the above-mentioned contents, which defines the quantitative variation of the active material to be filled into the space of the porous metal body, and easily and surely forms the lead mounting compression portion at a predetermined position. Can be. Further, according to this method, it is possible to process a single large-sized electrode into electrodes having various sizes according to the battery size, and it is possible to efficiently cope with the production of many kinds in small quantities.

As a method of removing a part of the active material at the edge of the porous metal body, a method of removing the active material with a brush may be used, but the method of removing the active material by applying ultrasonic vibration to the active material is the most reliable. Optimum because automation is easy and productivity is good.

The invention according to claim 2 is characterized in that the ultrasonic vibration is applied to a part of the edge of the porous metal body having a three-dimensionally connected space and filled with an active material therein. After removing the active material, this portion is pressed from both front and back surfaces, and a strip-shaped positive plate in which one end of a lead piece is connected to a compressed portion provided in the center of the thickness, and a spiral-shaped plate made of a strip-shaped negative plate and a separator It is an alkaline storage battery with a group.

By adopting such a battery configuration, an alkaline storage battery having a small variation in discharge capacity can be configured.

Further, since the lead piece attaching compression section is provided at the center of the thickness of the positive electrode plate, the lead piece can be attached to the compression section regardless of the front and back of the positive electrode plate. Moreover, since the attached lead pieces do not protrude in the thickness direction of the positive electrode plate, the configuration of the spiral electrode plate group can be smoothly performed.

[0015]

Next, specific examples of the embodiments of the present invention will be described.

15 parts by weight of a cobalt oxide powder is added to 100 parts by weight of nickel hydroxide and mixed with powder. Water is added to the mixture so that the ratio of water to the pre-paste becomes 25% by weight, and the mixture is kneaded. A material paste was made.

FIG. 1 shows a state in which an electrode is filled with an active material according to an embodiment of the present invention. As shown in FIG.
0mm, thickness 3.0mm, porosity 98%
On one surface of the porous metal body 1 having a three-dimensionally continuous space in the form of a strip having an average pore diameter of 200 μm, a length of 60
mm nozzle 2 was placed in a fixed state.

One side (lower surface) of the porous metal body 1 is supported, and while the porous metal body 1 is moved at a speed of 7 m / min in the length direction of the porous metal body 1, the active material paste is supplied from the nozzle 2 at a rate of 10 g / min.
The space portion of the porous metal body 1 was filled at a discharge speed of seconds. At this time, the distance between the porous metal body 1 and the nozzle 2 was 0.1 mm.

The porous metal body 1 filled with the active material paste is dried at 90 ° C. for 1 hour, pressurized with a roll press to reduce the thickness from 3.0 mm to 1.0 mm, and filled with the active material. After the density was increased, a horn (ultrasonic vibrator) of an ultrasonic oscillator was applied to a continuous portion of the edge of the porous metal body 1 while applying a pressure of 3 kgf, and a frequency of 40 kHz and an amplitude were applied to the active material. 70 μm ultrasonic vibration for 30 msec
Then, the active material is removed, and the removed portion is pressurized with the same pressure from both the front and back surfaces to obtain a width of 8 mm, a length of 7 mm,
A compression section 3 having a thickness of 0.2 mm was provided at the center of the thickness. The compressed portion 3 is attached to the edge of the porous metal body 1 in the longitudinal direction by 110 mm.
mm. FIG. 2 shows a front view of the porous metal body 1 provided with the compression section 3.

In this case, the active material filled in a part of the edge of the porous metal body 1 is first removed, and after the compression part 3 is provided, pressure is applied by a roll press machine to reduce the packing density of the active material. Although it can be raised, the metal porous body 1 at each position at the time of pressurization between the compressed part 3 without the active material and the part with the active material is
Since the elongation differs, it is somewhat difficult to reliably determine the position and size of the compression section 3.

According to the method shown in the above embodiment, since there is no large difference in the elongation of the porous metal body 1, the packing density of the active material can be made uniform and the position of the compression section 3 can be ensured. preferable.

The porous metal body 1 has a length of 110 mm and a width of 60 m so that the compressed portion 3 is located at the center in the length direction.
The electrode manufactured by cutting into m is referred to as an electrode A in the example of the present invention, and a schematic plan view thereof is shown in FIG. The electrode A is filled with the active material paste from one side and the discharge speed thereof.
It comprises a portion a filled with the active material and a portion b made of an extremely thin layer not filled with the active material.

As described above, in the embodiment of the present invention, the compression unit 3
Is provided on the porous metal body 1 and then cut into a predetermined size to form an electrode. However, the compression unit 3 may be provided after the porous metal body 1 is cut into a predetermined electrode size first.

For comparison, a compressed portion is provided in advance on a part of the edge of the porous metal body on the same side as the active material filling surface, and a concave portion facing the compressed portion is provided on the opposite side. Was filled in a porous metal body and cut to obtain an electrode of a comparative example.

In this case, in the comparative example, the compressed portion is provided on the same side as the filling surface in the porous metal body. When the active material is filled in the space of the porous metal body, the compressed portion becomes substantially non-porous. Therefore, the active material is directly bounced off, and can hardly be filled, and from the cut end of the recess facing the compression part,
A part of the active material escapes to the outside by being pressed by the surrounding filling pressure. As a result, the filling amount of the active material is smaller in the vicinity of the compression part than in other parts, and thus the dispersion of the filling amount of the active material increases.

In the embodiment, since the compressed portion is provided after filling the porous metal body with the active material, the active material is uniformly distributed over the entire porous body excluding the compressed portion without variation in the filling amount of the active material. The substance is filled.

Next, the electrode A prepared above was used as the positive electrode 4A, and the compressed portion 3 was 3 mm wide, 10 mm long and 0.15 thick.
One end of a 5 mm lead piece 5 was spot-welded to the surface side of the thin metal portion b of the compressed portion 3 where the active material was not filled. FIG. 4 shows a front view of the positive electrode 4A, and FIG. 5 shows a schematic plan view thereof. As shown in FIG. 5, the lead piece 5 is accommodated in the compression section 3 and does not protrude in the thickness direction of the positive electrode 4A, so that the configuration of the spirally-shaped electrode group described below can be smoothly performed.

The positive electrode 4A, the hydrogen-absorbing alloy negative electrode 6, and an electrode plate group formed by spirally winding the two between the two via a polypropylene nonwoven fabric separator 7 are inserted into a metal battery case 8, After injecting a predetermined amount of the alkaline electrolyte, the upper part of the case 8 is sealed with a sealing plate 9 also serving as a positive electrode terminal, and a long A size (outer diameter 16.5 mm, height 66.0).
mm) of the nickel-hydrogen storage battery (nominal capacity 3300 mAh) in the example of the present invention. FIG. 6 shows a configuration diagram of this battery.

For comparison, ten batteries having the same configuration as the example of the present invention except that the electrode of the comparative example was used as the positive electrode were configured as batteries of the comparative example.

The results of variations in the average discharge capacity and the discharge capacity of each of the 10 batteries of the example of the present invention and the comparative example when the battery was discharged at a current value of 3300 mA until the battery voltage reached 1.0 V are shown in FIG. Shown in 1).

[0031]

[Table 1]

As shown in Table 1, the average discharge capacity of the battery of the example was 3300 mAh, and that of the battery of the comparative example was 3300 mAh.
It is 200 mAh, and it can be seen that the discharge capacity of the example is larger than that of the comparative example. Further, it can be seen that the variation in the discharge capacity of the example is 4.4% smaller than that of the comparative example.

This is because, in the battery of the embodiment, since the positive electrode 4A having a small variation in the active material filling amount is used, the variation in the discharge capacity is as small as 0.9% as shown in Table 1, and the average discharge capacity is small. Although the capacity of 3300 mAh comes out as in the case of the nominal capacity, in the comparative example, the vicinity of the concave portion facing the compression portion connected to the lead piece involved in the discharge has a smaller amount of the active material than the other portions, and the variation is smaller. Because of the increase, the average discharge capacity of the battery of the comparative example is lower than the nominal capacity by 100 mAh, and the variation thereof is also increased.

In the embodiment of the present invention, the electrode is formed by filling the active material paste on one side of the porous metal body 1 having a three-dimensionally connected space. A similar effect can be obtained by filling the paste to form an electrode.

[0035]

As described above, according to the electrode manufacturing method of the present invention, the active material is filled into the space of the strip-shaped porous metal body having the three-dimensionally connected space without quantitative variation. At the same time, an electrode in which the lead mounting compression section is formed simply and reliably can be formed, and by using the electrode to form an alkaline storage battery, an alkaline storage battery with less variation in discharge capacity can be provided.

Further, in the method of the present invention, the compressed portion for attaching the lead piece is provided after filling the active material into the porous metal body, so that the electrode having a large size has various dimensions of the compressed portion for attaching the lead. Electrodes and electrodes having various dimensions can be prepared, and it can efficiently cope with the production of various types of batteries in small quantities.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which a porous metal body is filled with an active material according to an embodiment of the present invention.

FIG. 2 is a front view of the same electrode provided with a compression section.

FIG. 3 is a schematic plan view of the electrode A.

FIG. 4 is a front view of a positive electrode 4A obtained by welding one end of the lead piece.

FIG. 5 is a schematic plan view of the positive electrode 4A.

FIG. 6 is a configuration diagram of the nickel-hydrogen storage battery.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Porous metal body having three-dimensionally connected space 2 Nozzle 3 Compressor 4 Positive electrode 5 Lead piece 6 Hydrogen storage alloy negative electrode 7 Separator 8 Battery case 9 Sealing plate

Claims (2)

[Claims] 1. A paste-like kneaded material mainly composed of an active material is discharged onto a strip-shaped sponge-like porous metal body having a space three-dimensionally connected and filled into the space of the porous metal body. Before or after cutting the porous body to a predetermined size, ultrasonic vibration is applied to a part connected to the edge of the porous metal body to remove the paste-like kneaded material at the part, and the part is added from both front and back surfaces. A method for producing an electrode for a battery in which a compression portion for attaching a lead piece is provided at the center of the thickness by pressing. 2. After removing the active material by applying ultrasonic vibration to a part of an edge of a porous metal body having a space connected in a three-dimensional manner and filled therein with an active material. An alkaline storage battery comprising a band-shaped positive electrode plate in which one end of a lead piece is connected to a compressed portion provided in the center of the thickness by pressing this portion from both front and back surfaces, and a spiral electrode plate group including a band-shaped negative plate and a separator .