JPS59130072A - Manufacturing method of collector for battery - Google Patents

Abstract

PURPOSE:To make up an embossing part into a specified form without entailing any cracks there, by having one side of molds constituted of a steel while the other side one of relatively soft metals including aluminum, brass, copper, zinc and the like, in time of embossing operation. CONSTITUTION:A current collector 21 used for a spiral type nonaqueous electrolytic battery is made up of forming a lot of openwork holes (a)... in a sheet of stainless steel or iron, and when a steel plate is used, a multihold plate being additionally nickel-plated and having corrosion resistance, namely, a punched metal is made up and then a lot of embossing parts (b)... are formed all over the surface. And, when these embossing parts (b)... are machined, a drag 32 provided with a convex part 31 corresponding to these embossing parts (b)... is set down to what is made of steel while a cope 34 provided with a concave part 33 corresponding to other embossing parts (b)... is made up of relatively soft metals, for example, aluminum, brass, copper, zinc and suchlike. As a result, any cracks around each openwork hole (a) caused by the edge of each mold can be surely prevented, while each of these embossing parts (b)... comes possible to be amply drawn out to the extent of reaching the specified form.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a battery current collector that also serves as a core material that holds a positive electrode active material in a thin layer, such as a positive electrode side current collector of a non-aqueous electrolyte battery.

As is well known, non-aqueous electrolyte batteries can easily be made compact and have a large discharge capacity due to the high theoretical energy density of the negative electrode such as lithium, but on the other hand, the low conductivity of the organic electrolyte makes it difficult It is difficult to produce output, and in order to compensate for this, for example, in cylindrical batteries, the centering element has a spiral structure to increase the polarization area. FIG. 1 shows a specific example of its configuration. In detail, this non-aqueous electrolyte battery consists of a cylindrical stainless steel battery case 1 with an open top, and a battery case 1 that is housed inside the battery case 1. The power generating element 2 is mainly composed of a power generating element 2, a positive electrode terminal 3 which also serves as a lid of the d-oil case 1, and a gasket 4.
．． Positive electrode6. A structure in which negative electrodes 7 are alternately stacked and wound in a spiral shape is used. The power generating element 2 is housed in the battery case 1 with an insulating plate 8 disposed thereon, and after injecting the non-aqueous electrolyte 9 therein, the battery case 1 is sealed with the positive terminal 3 and the gasket 4. be. 1, the positive terminal 3 is connected to the positive terminal 6 by the positive lead wire 10.
The battery case 1 is connected to the negative electrode 7 by a negative electrode lead wire 11.

The negative electrode 7 is made of, for example, a lithium metal ribbon crimped onto a nickel strip, and the separator 5 is made of a volupubilene nonwoven fabric, each of which is formed into a strip.

On the other hand, the positive electrode 6 is made of a porous strip-shaped current collector as a core material, and a paste-like positive electrode mixture is coated on both sides of the core material in a thin layer and dried and solidified, and the positive electrode active material includes:
For example, a material that is mainly composed of manganese dioxide, mixed with carbon as a conductive agent, and further kneaded with a binder is used.

Here, as the porous current collector in the conventional positive electrode 6, a so-called expanded metal made by expanding a thin metal plate with a large number of slits in a direction perpendicular to the slits, or a thin metal plate with a large number of slits formed therein, is used. A so-called punched metal with through holes was used. The above-mentioned punched metal has the advantage of being much cheaper than expanded metal, which has been widely used in the past, but on the other hand, it is slightly inferior to expanded metal in terms of retention of the positive electrode mixture, and it is difficult to assemble batteries. A drawback has been pointed out that the active material is likely to peel off during or after completion.

Therefore, in order to supplement the retention performance of such a positive electrode mixture, the present applicant has previously proposed forming a larger number of embossed portions on the punched metal. Punched metal with embossed parts formed in this way can secure sufficient retention performance for the positive mixture like the expanded metal described above, and even if this embossing process is taken into account, it is far more effective. It can be provided at low cost.

However, it is of course not easy to perform good embossing on an extremely thin metal plate in which a large number of through holes have been formed in advance. This type of embossing is usually
This is done by squeezing the metal plate with a pair of non-uniform molds that have four parts and a convex part corresponding to the embossed part, but if the through hole is not formed in advance as mentioned above, Cracks are likely to occur from the periphery. And this crack is
When the positive electrode 6 is spirally wound, it not only causes poor adhesion with the positive electrode mixture, but also especially when a nickel-plated iron plate is used as the punched metal. The iron base is exposed, causing corrosion, which increases the internal resistance of the battery and reduces storage performance. Additionally, attempts have been made to construct one of the molds from elastically deformable rubber, but in this case, although the occurrence of the above-mentioned cracks can be prevented, the embossed part cannot be sufficiently compressed into a predetermined shape. As a result, the retention performance of the positive electrode mixture cannot be significantly improved.

This invention was made in view of the above circumstances,
As a result of various attempts by the present inventor, during embossing, one mold was made of steel, and the other mold was made of aluminum, brass, etc.
It was discovered that if the electrode is made of relatively soft metal such as copper or zinc, the embossed part can be formed into a predetermined shape without any cracking. The purpose of the present invention is to provide a current collector that has good retention performance and is inexpensive.

That is, the method for manufacturing a battery current collector according to the present invention is as follows:
In a method for manufacturing a battery current collector that also serves as a core material that holds a positive electrode mixture in a thin layer, after forming a large number of through holes in a thin metal plate, one mold made of steel and one mold made of aluminum, brass, copper, This method is characterized in that the thin metal plate is pressed between the mold and the other mold made of a relatively soft metal such as zinc to form a large number of embossed portions.

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

First, FIG. 2 shows an example in which the above-mentioned positive electrode 6 for a spiral type non-aqueous electrolyte battery is constituted by a current collector 21 manufactured according to the present invention. The current collector 21 is used as a core material, and a paste-like positive electrode mixture n is applied to both sides of the core material, and this is dried and solidified.

Here, the above-mentioned collection c1 body 21 is a perforated plate, that is, a punch, which is made by forming a large number of through holes a... in a thin plate of stainless steel or iron, and when using an iron plate, it is plated with nickel to make it corrosion resistant. After that, a large number of embossments -ib... are formed over the entire surface. When processing the embossed portions b..., as shown in FIG.
On the other hand, the upper mold part in which the recessed part corresponding to the embossed part b is formed is made of a relatively soft metal such as aluminum, brass, zinc, etc., and between the two mold parts 32 and 34 The above-mentioned punched metal is sandwiched between the two and pressurized. The same thing can be done if the lower mold 32 is made of a relatively soft metal such as aluminum and the upper mold is made of steel, and both molds are roller-shaped and the belt-shaped punched metal is sequentially embossed. It can also be applied when

As a result of forming one of the embossing molds 32 and 34 from aluminum, brass, copper, zinc, etc., it is possible to reliably prevent cracks around the periphery of the through-hole a that would otherwise occur due to the edges of the mold. At the same time, it is possible to sufficiently squeeze out the embossed portion b... into a predetermined shape. Therefore, the retention performance of the positive electrode mixture 4 is much better than that of punched metal with only through holes a, which have been attempted in some cases in the past. Even if the embossed part b... is used, corrosion will not occur from the embossed part b.

The above description has mainly been about the cylindrical non-aqueous electrolyte battery shown in FIG. 1, but it goes without saying that the present invention is not limited to this. It can be applied to various thin positive electrodes that require a current collector such as a dead metal.

As is clear from the above explanation, according to the method for producing an assembly according to the present invention, it can be used as a substitute for expensive expanded metals, is inexpensive, has excellent positive electrode mixture retention performance, and is free from corrosion due to cracks. It is possible to provide a metal-type current collector with no defects.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of the configuration of a cylindrical non-aqueous electrolyte battery, FIG. 2 is a perspective view showing the structure of the positive electrode to which the present invention is applied, and FIG. It is an explanatory diagram. DESCRIPTION OF SYMBOLS 1... Battery case, 2... Power generation element, 5... Separator, 6... Positive electrode, 7... Negative electrode, 21...: Current collector, η... Positive electrode mixture, 32... ...lower mold, 34...upper mold. Patent applicant: Fujitun Kei Kagaku Co., Ltd. Agent Patent attorney - Kensuke Iro Figure 1

Claims (1)

[Claims] ) In a method for manufacturing a battery current collector that also serves as a core material that holds a positive electrode active material in a thin layer, after forming a large number of through holes in a thin metal plate, one mold made of steel and one mold made of aluminum, brass,
The above-mentioned gold 1. @A method for manufacturing a current collector for a battery, characterized by forming a large number of embossed portions by pressing a thin plate.