JPS6048865B2 - Manufacturing method for electrode plates for alkaline storage batteries - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing electrode plates for alkaline storage batteries, particularly cadmium cathode plates for nickel-cadmium storage batteries, and provides a method for obtaining electrode plates with excellent high rate discharge characteristics with good workability. It is intended to provide.

The cadmium cathode plate of a sealed nickel-cadmium storage battery is manufactured using a sintered electrode plate manufactured by impregnating a sintered nickel body with an aqueous solution of cadmium salt, and a sintered plate manufactured by impregnating a sintered nickel body with an aqueous solution of cadmium salt, and a cadmium oxide powder, conductive material powder such as carbonyl nickel, and adhesive. A paste-type electrode plate is generally used, which is manufactured by mixing appropriate amounts of the material, its solvent, and reinforcing single fibers, applying the mixture as a paste to both sides of a porous core material that is a support, and drying it. .

The present invention is an improvement on the latter method of manufacturing paste-type electrode plates, which has excellent workability and battery performance.

As shown in FIG. 1, the conventional method for producing a paste-like cathode plate is to use a strip-shaped nickel or nickel-plated iron core material 1a with a porous central portion 1 and non-porous side edges 2, 2'. A paste-like cathode active material 3 is applied to both sides of the plate, and the finished cathode plate after cutting is passed through a doctor knife or slitter 5 having an appropriate gap 4 as shown in FIGS. 2 and 3. After scraping off the paste-like cathode active material 3 on both sides of the core material with a soft rubber 6 interposed in the gap between the knives 5 at positions corresponding to the current collector parts, and then drying,
It was chemically converted by charging and discharging in an alkaline aqueous solution.

After this, in order to prevent the entire core material from bending or bending, both edges of the core material are stretched a certain amount in the longitudinal direction of the core material, and the entire core material is pressurized to reduce the porosity of the active material coated area. After applying a roller press to adjust the thickness to a constant value, the cathode plate was cut to a predetermined size to obtain the desired cathode plate. However, in this conventional method, when forming a large-sized electrode plate before chemical formation into a substrate of a predetermined width, adhesive material and reinforcing single fibers are mixed into the paste cathode active material, and the cathode active material paste is Due to its viscous state, it was difficult to scrape off only a predetermined portion of the paste to form a current collector.

In other words, in the process of scraping off the paste in the part that forms the current collector with the soft rubber interposed between the doctor knives when applying the active material in paste form as shown in Figure 2, the reinforcing single fibers mixed in the paste cannot be completely cut. , and the adhesive also acts, so not only the current collector forming part but also the cathode active material at both ends peels off from the core material and becomes uneven. Therefore, it is difficult to assemble the battery using the cut cathode plate. This resulted in non-uniformity in battery performance after formation. Furthermore, since the paste is not completely removed from the current collector portion and a thin layer of paste remains, there are other problems such as the remaining paste falling off during battery formation and causing a short circuit accident.

The present invention applies a paste-like cathode active material to both sides of a nickel or nickel-plated iron core material, dries it to form a large-sized electrode plate, and then cuts both sides of the part that will become the current collector of the desired cathode plate. Using a sharp knife material such as a round knife or a cutter knife, make a score with a certain width only on the cathode active material, and then use a cutter with multiple cutting edges such as a slotted milling cutter to cut between the marks without damaging it. By scraping off only the cathode active material, a cathode active material portion with a uniform width and a core current collector portion completely exposed on both the top and bottom surfaces are formed, which eliminates the above-mentioned problems and improves battery performance. There are some that provide excellent electrode plates.

Embodiments of the present invention will be described below with reference to the drawings. 1st
A large number of through holes are provided in the central portion 1 similar to that shown in the figure, and both side edge portions 2, 2' are made non-porous with a thickness of 0. IT
WL nickel or nickel metal. A core material 1a made of a metal plate is prepared, and as shown in FIG.
After drying, the substrate is passed between a pair of pressure rollers 7 for temporarily adjusting the thickness of the substrate. Next, a pair of round knives 8 with a cutting edge thickness of 30 μm and an outer diameter of 10077!771 are applied to the edge of the portion that will form a current collector with a width of 2 wfm on both the upper and lower surfaces, and the core material is pressed at a certain pressure, for example within the range of 4 to 6 k9/go. Incisions are made only in the paste-like cathode active material 3 that has been applied and dried on both the upper and lower surfaces of the core material. As a result, the paste inside and outside of the reinforcing single fibers and muscles mixed in the paste is completely separated. After this, the cathode active material 3 in the scored part is cut into a slotted milling cutter 9 with a blade width of 1.9 to 2.0 m (771) and an outer diameter of 70 Tnm, and the electrode plate feed rate is increased to 60 to 1 tn. The active material in the interstitial areas is scraped off at the rotational speed. In this step of making the creases and scraping off the active material between the creases, in order to form sharp edges on the active material on both edges of the part that will become the current collector, first make the creases, then remove the active material between the creases. It is best to scrape off the paste-like cathode active material on the part that will become the body.

At this time, a round knife is placed above and below the electrode plate to make the incision.
If the gap between the top and bottom of each slotted milling cutter used to scrape off the active material is set to a certain size, it will bite into the paste-like active material and damage the surface of the core metal due to deflection or warpage, or in extreme cases, the core metal surface will be damaged. Cutting of the material occurs. In order to solve this problem, the round knife and slotted milling cutter have a spring mechanism that bites into the paste-like cathode active material on both sides of the core material under constant pressure, thereby preventing variations in the amount of active material applied on both sides of the core material. Even if this happens, the round knife and slotted milling cutter only come into contact with the surface of the core metal under a constant pressure, and the excess pressure is released, so the core metal will not be damaged or cut. After forming the current collector in this way, the electrode plate is chemically formed in the chemical conversion device 10 as in the conventional case, and the cathode active material is electrolytically reduced in an alkaline solution in order to increase the active material utilization rate during charging and discharging. Oxidize.

Next, in order to prevent the entire core material from bending or bending,
Then, the core material is stretched by a stretching device 11 by about 3 Tnm in the longitudinal direction. After that, in order to adjust the porosity and thickness of the active material part to a constant level, the cutter 1 is passed through the roller press 12.
If the electrode plate is cut to a predetermined width in step 3, a rectangular unit electrode plate 14 corresponding to the battery size can be obtained. Figure 5 shows a spring mechanism that applies constant pressure to the round knife and slotted milling cutter placed above the electrode plate, 15 and 16 are coil springs;
17 and 18 are pressure adjusting rods to which one end of a coil spring is fixed.

The one on the lower side of the electrode plate is constructed in the same way. Further, FIG. 6 is a top view of the active material in the scored portion removed by a slot milling cutter, and the porous core material 1a is exposed in a thin band shape.

This applies not only to the upper side of the electrode plate but also to the lower side. As described above, in the manufacturing method of the present invention, after coating the paste-like cathode active material on both sides of the core material and drying, the paste-like active material in the part that will form the current collector part of the desired cathode plate after cutting is streaked with a knife material. By cutting off the active material between the streaks with a slotted milling cutter, the boundary between the current collector part and the active material coated part becomes a straight line with sharp edges, resulting in uniform battery performance. It is possible to provide an excellent electrode plate.

[Brief explanation of the drawing]

Figure 1 is a partial cross-sectional view of a conventional porous strip core material coated with a paste cathode active material, and Figure 2 is a top view of a part of the paste active material scraped off with soft rubber. , FIG. 3 is a cross-sectional view taken along the line ■-■' in FIG. FIG. 6 is a side view of the spring mechanism that provides a pressing force, and a top view with the active material of the current collector portion removed. 1... Porous center, 2,2'...
・Non-porous side edges, 1a... Band-shaped core material, 3...
... Paste cathode active material, 5 ... Doctor knife, 6 ... Drying oven, 8 ...
Knife material, 9... Slit milling cutter, 10...
...Chemical conversion equipment.

Claims (1)

[Claims] 1. On both sides of a porous belt-shaped core material with non-porous edges,
A process of continuously applying and drying a paste-like cathode active material mixed with conductive material powder, adhesive material, and reinforcing single fibers, and a process of continuously applying and drying the paste-like active material mixed with conductive material powder, adhesive material, and reinforcing single fibers, and applying the desired amount after cutting of the paste-like active material that has been applied and dried on both sides of the core material. The process includes scoring the portion of the cathode plate that will become the current collector with a pair of knife materials, and cutting off the active material between the streaks with a slotted milling cutter. A method for manufacturing an electrode plate for an alkaline storage battery, characterized in that the pressing force of the slotted milling cutter for cutting off the core material is adjusted so that it contacts the core material at a constant pressure from both the upper and lower surfaces.