JPH06314563A - Battery - Google Patents

Abstract

PURPOSE:To prevent welding strength from varying or deteriorating by forming a battery can using an armoring can having a coarse outside surface and a dense inner surface, and reducing fluctuations in the electrical resistance of a spot welded portion and in the amount of electricity transmitted to the welded portion, thereby reducing sputtering of sparks. CONSTITUTION:A negative electrode 6 having metal lithium therein as active material and a positive electrode 5 having manganese dioxide therein as active material are arranged into a spiral structure with a separator 7 therebetween. A power generating element, comprising the spiral structure of the positive and negative electrodes in which lead plates 2 for connection to external terminals, is put in an armoring can 1 with the positive lead plate 9 up and the negative lead plate 2 down. The positive lead plate 9 is then connected to a sealing body 10 which serves also as an external positive terminal, and the negative lead plate 2 is spot welded to the armoring can 1 which serves also as an external negative terminal. Thereafter, an electrolyte is injected into the battery and the sealing body 10 and the upper portion of the armoring can 1 are calked into a cylindrical shape, together with insulating packing 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery, and more particularly to a battery outer can, and more particularly to a battery outer can whose surface is modified.

[0002]

2. Description of the Related Art As a battery outer can, a thin steel or stainless steel plate is pressed into a can. Usually, this outer can not only stores the power generating element such as the electrode plate and the electrolytic solution, but also serves as an external electrode terminal for taking out electricity from the power generating element to the outside.
Therefore, even in the case of the final product, a part of the outer can that becomes the external electrode terminal is exposed to the outside. Therefore, it is necessary to prevent the exposed portion from deteriorating the appearance of the battery and reducing the commercial value of the battery. Therefore,
It is desirable to use a clean outer finish for the battery outer can from the beginning, but since the battery outer can can be damaged by scratches during battery manufacturing work, it is not only a good finish. It is desirable that the material is such that the scratches are not noticeable.

In particular, in a battery of a type such as a nickel-cadmium battery, a nickel-hydrogen battery, a lithium battery, and a lithium-ion battery, which takes out a large current with high efficiency, there is a strong demand for an outer can that is not easily scratched. This type of battery has a structure in which the area of the positive electrode plate is widened to extract a large current, and the electrode plate is spirally wound through a separator. It is configured to be electrically connected to the outer can which is an external electrode terminal by spot welding inside the bottom. Then, since high heat is applied to the outer can during this spot welding, welding marks are left on the exposed portion, and it is necessary to make the welding marks inconspicuous.

By the way, a so-called dull finish specification can material in which the surface of a steel plate such as steel or stainless steel is appropriately roughened is
It has characteristics that the surface is not easily scratched and scratches and welding marks are not noticeable, and it is suitable as a can material for battery outer cans. Therefore, a can material obtained by subjecting a steel plate to a dull finish is widely and generally used for battery outer cans. Conventionally, the dull finish of the steel sheet has been performed by rolling a nickel-plated steel sheet raw material having a predetermined thickness with a rolling device as shown in FIG. 3 using a roll having a moderately rough surface. In order to prevent the steel sheet from warping after finishing, this surface finishing process is performed integrally on the front and back sides by using rolls having the same roughness on the upper and lower sides. Therefore, the conventional dull-finished steel sheet has dull finish specifications on both the front and back sides.Of course, the battery outer can manufactured using this dull-finish steel sheet has a dull finish specification not only on the outer surface but also on the inner surface. Was there.

[0005]

However, when the inside of the outer can has a dull finish, there are the following inconveniences. That is, as described above, in high-power type batteries such as nickel-cadmium batteries, it is necessary to weld the lead plate to the inner surface of the bottom of the can, but the conventional dull-finished outer can has a dull finish on the inside as well. The surface to be spot-welded is rough. Therefore, in spot welding,
The contact between the lead plate and the surface becomes unstable or insufficient, and the amount of electricity supplied and the electric resistance fluctuate. Therefore, the heat generation temperature during welding fluctuates, and as a result, the welding strength varies. Further, when the contact is insufficient, the sparks fly, and so-called dust (a molten metal solidified into a needle shape) occurs. Since this dust has a needle-like and brittle property, in addition to lowering the welding strength, it has fallen off from the weld and enters the inside of the battery, causing a battery short circuit and other troubles.

As described above, in the battery prepared by using the conventional outer casing having the dull finish specification, sufficient welding strength cannot be obtained, so that the welded portion is detached due to vibration or the like, and the electric potential between the electrode plate and the outer can is increased. Poor connection is likely to occur, and dust entering the battery may cause deterioration of the battery. Therefore,
There was a problem that the electric capacity that the battery originally had could not be taken out completely.

Therefore, an object of the present invention is to provide a battery outer can in which scratches and welding marks on the outer surface are less noticeable and spot welding can be suitably performed on the inner surface.

[0008]

In order to achieve the above-mentioned object, the present invention provides a battery outer can, which also serves as one external terminal of an electrode, in which the outer surface is rough and the inner surface is densely prepared. It is a can.

[0009]

According to the present invention, since the outer surface of the battery outer can is roughened, it is less likely to be damaged by scratches or the like during the battery manufacturing work, and even if scratched, it is not noticeable. Therefore, the appearance of the battery can be kept good, especially
Weld marks due to heat during spot welding can be made inconspicuous.

On the other hand, since the inner surface of the battery outer can is densely prepared, spot welding can be suitably performed.
That is, since the inner surface of the battery, which is the welding surface, is dense, the contact state between the surface and the object to be welded (lead plate) is stabilized during spot welding. Therefore, fluctuations in electric resistance and energization amount in the spot welding area are reduced, and fluctuations in welding temperature and sparks are prevented. Therefore, the electrode lead plate can be reliably welded to the inside of the outer can, and the deterioration of the battery such as a short circuit due to dust can be prevented.

Further, in the present invention, since the outer surface of the outer can is roughly prepared as described above, the welding marks formed on the outer surface by the heat during the spot welding can be made inconspicuous. Therefore, the deterioration of the battery appearance due to spot welding can be reduced.

[0012]

〔Example〕

(Preparation of outer can) A battery outer can used for the battery of the present invention was prepared as follows. First, using a rolling device as shown in FIG. 3, a grid finishing roller having an iron powder sprayed on the surface is mounted as the upper roll, and a smoothing roller finished by a grinder is mounted as the lower roll. The nickel-plated steel sheet produced by the method was prepared into a thin plate (0.25 mm thick) having a bright finish on one side and a dull finish on the other side. The center line average roughness (Ra) defined in JIS B060 1976 of this thin plate surface was 0.4 μm on the dull finish surface side and 0.1 μm on the bright finish surface side. The thickness of nickel plating of the thin plate was 10 μm or less.

Then, the outer can of the present invention having a diameter of 16.3 mm with a dull finished surface on the outside and a bright finished surface on the inside was prepared by press drawing using this thin plate. The outer can of the present invention, the outer surface of which is dull-finished and the inner surface of which is bright-finished, is called outer can A. (Preparation of Battery) FIG. 2 shows the structure of the battery of the present invention. The battery of the present invention has a negative electrode having metallic lithium as an active material through a separator, and a positive electrode having manganese dioxide as an active material in a spiral structure, and the positive and negative spiral structure electrodes have external electrode terminals respectively. A lead plate (thickness 0.1 mm, width 4 mm) for connection is provided. Then, this power generation element provided with the lead plate is put in the outer can A so that the positive electrode lead plate is led out and the negative electrode lead plate is led out (the outer can bottom side), and the positive electrode lead plate is attached to the external positive electrode. The negative electrode lead plate was spot-welded to the outer can A (bottom portion) which also functions as an external negative electrode terminal. After that, an electrolytic solution was injected, and the sealing body and the upper part of the outer can were caulked together with the insulating packing to prepare a cylindrical sealed manganese dioxide lithium battery.

Here, a spot welding method for the bottom of the outer can and the negative electrode lead plate will be described. As shown in Figure 1,
In the center hole of the spiral structure electrode housed in the outer can,
An electrode rod (tip diameter 1.5 mm) is inserted, while a receiving electrode (diameter 12 mm) is set on the outer bottom of the outer can so as to cover the bottom. Then, with a weight of 10 kg added to the electrode rod, a welding current of 1.70 KA, 1.6
Spot welding was performed at 5 KA and 1.55 KA. [Comparative Example] In the preparation of the above-mentioned outer can, a steel plate having a surface finish of bright / dull, bright / bright, dull / dull (front surface / back surface) was prepared by changing the combination of the upper and lower rolling rolls. Using the same method as above, an outer can made bright / dull, bright / bright, dull / dull (outside / inside) was prepared. Then, using this outer can, a battery having the same structure as that of the above-described embodiment of the present invention was prepared, and spot welding was performed in the same manner. Among the batteries prepared in this way, a battery in which the surface finish of the outer can is bright / dull is referred to as a comparative battery B, a bright / bright battery is referred to as C, and a dull / dull battery is referred to as a comparative battery D.

[Experiment] This Example Battery A and Comparative Example Battery B
The welding strength and the appearance of the exposed portion were examined for each of the 20 to D batteries. The results are shown in Table 1.

[0016]

[Table 1]

As is clear from Table 1, in the case of a welding current of 1.70 KA, a sufficient strength of 3.0 to 3.2 Kg was obtained for all the batteries A to D. However, occurrence of dust was confirmed in B and D where the inner surface was dull specification, and welding marks were conspicuous in B and C where the outer surface was bright specification.

When the welding current was 1.65 KA, the welding strength was the same as in the above case, and almost no change was observed. Further, although the degree of dust generation was somewhat suppressed, it was still observed in B and C. When the welding current was further reduced to 1.55 KA, the welding strength was insufficient in all the batteries A to D, and the lead plate was peeled off only by applying a load such as lightly pulling it by hand. Especially in B and D, the degree was large.

From the above results, from the viewpoint of welding strength, 1.
A welding current of 65 KA or more is desirable, but with this welding current, if the inside of the outer can is dull-finished (B and D), dust will occur, and if the outer surface is bright-finished, it will impair the appearance of the battery. It can be seen that the welding marks become noticeable. Further, when the inner and outer surfaces of the outer can are both bright-finished (C), it is good in terms of welding strength and occurrence of dust, but it is found that the appearance of the battery deteriorates due to welding marks. On the other hand, the battery A of the present invention in which the inner surface was bright-finished and the outer surface was dull-finished had good results in terms of welding strength, occurrence of dust, and appearance.

In this embodiment, the center average roughness (Ra) of the dull finished surface was 0.4 μm and the center average roughness (Ra) of the bright finished surface was 0.1 μm. From 0.2 μm or more, the effect of making scratches and welding marks during spot welding less noticeable appears, and about 0.4 μm is particularly preferable. Therefore, it is desirable to set the roughness of the front and back surfaces to 0.2 μm or more for the dull finish on the outer surface and less than 0.2 μm for the bright finish on the inner surface.

[0021]

As described above, according to the present invention, since the outer surface of the battery outer can is roughened, it is less susceptible to damage such as scratches during the battery manufacturing work, and is associated with scratches and spot welding. It has the effect of making welding marks less noticeable. Therefore, the appearance of the battery can be kept good.

On the other hand, since the inner surface of the battery outer can is densely prepared, the contact state between the object to be welded (lead plate) and the surface can be made suitable and stable. For this reason, fluctuations in electric resistance and energization amount at the spot welding site are reduced, and spark scattering due to poor contact is reduced. Therefore, it is possible to prevent variations in welding strength and decrease in welding strength due to fluctuations in heat generation temperature and dust, and it is possible to reliably spot weld the object to be welded to the inside of the outer can and eliminate dust that enters the battery. It is possible to prevent battery deterioration such as short circuit caused by

In the sealed battery, the stored power generating element is sealed in the outer can by using a resin insulating packing. At this time, if the inner side of the outer can is smooth, the adhesion with the packing is improved. Therefore, the battery outer can of the present invention is particularly convenient as an outer can for a sealed battery.

[Brief description of drawings]

FIG. 1 is a diagram showing a spot welding state with respect to a battery outer can containing a power generation element.

FIG. 2 is a diagram showing a structural example of a sealed complete battery.

FIG. 3 is a diagram showing a surface finishing process of an outer can original plate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichizo Abe 2-18 Keihan Hondori, Moriguchi City Sanyo Electric Co., Ltd. (72) Inventor Fukuoka Satoru 2-18 Keihan Hondori, Moriguchi City Sanyo Electric Co., Ltd. In-house (72) Inventor Hidetaka Hatanaka 2-18 Keihan Hondori, Moriguchi Sanyo Electric Co., Ltd. In-company (72) Inventor Michiyoshi Tanaka 1302 Higashi-Toyoi, Shimomatsu-shi, Yamaguchi Toyo Kohan Co., Ltd. Shimomatsu Factory

Claims (3)

[Claims] 1. A power generation element comprising a positive electrode, a negative electrode, and a separator, an electrolytic solution, a battery outer can that also serves as one external terminal of an electrode, and an electrical insulation from the battery outer can that also serves as the other external terminal of the electrode. A battery including a sealing body, wherein the battery outer can is made of a conductive member having a rough outer surface and a tightly adjusted inner surface. 2. The battery according to claim 1, wherein the conductive member is a metal plate. 3. The average roughness of the outer surface of the battery outer can is 0.2 μm or more, and the average roughness of the inner surface is 0.2 μm.
It is less than m, Claim 1 or Claim 2 characterized by the above-mentioned.
Battery described.