JPH11207470A - Welded structural body between battery and lead material, and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably provide high welding strength by forming an organic insulation film on the surface of a battery and/or the surface of a lead material, and welding the lead material to the surface of the battery by the parallel resistance welding method. SOLUTION: Two nuggets 5 are formed between a surface 1a of a battery (container) of a battery 1 and a lead material 2, and the battery 1 and the lead material 2 are welded to each other. An organic insulation film 6 is interposed between the surface 1a of the container and a back side 2b of the lead material 2 except the parts of the nuggets 5. The thickness of the organic insulation film 6 is preferably 60-90 nm. The material of the organic insulation film 6 includes the mixture of the straight hydrocarbon of 15-20 in carbon number such as silicone oil and liquid paraffin, an electric insulation material such as the phenol resin and alkyl-phenol resin modified by rosin and rosin ester, and various kinds of rust preventive materials.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welded structure of a battery and a lead material and a method of manufacturing the same. More particularly, the present invention relates to a welded structure of a battery and a lead material suitable as a drive source of an electric vehicle and a method of manufacturing the same.

[0002]

2. Description of the Related Art With the spread of various electric and electronic devices, the number of cases in which a plurality of batteries as driving sources are packaged into a battery pack and the battery pack is directly incorporated into the device has been rapidly increasing. ing. Recently, an electric vehicle has been attracting attention as an environmentally friendly clean vehicle, and its driving source is a package in which a plurality of batteries are packaged.

[0003] As described above, when a plurality of batteries are packaged and actually used, the batteries must be charged or discharged.
It is necessary to electrically connect each battery or between the package terminal and the battery with a lead material. That is, it is necessary to fix the lead material to the outer surface of the battery, for example, to a part of the surface of the battery container such as the lid and the bottom. For connection between a battery and a lead material, generally, a parallel resistance welding method as described below is applied.

First, as shown in FIG. 7, a lead material 2 to be welded is arranged on a surface 1a of a battery container 1 (in the case of the figure, a bottom surface of the battery container). In addition, the battery case 1 has conventionally been made of, for example, Ni in which the surface of a low carbon steel plate is plated with Ni.
The lead material 2 is manufactured from a plated steel sheet, and a small piece of Ni alone or a Ni-plated steel sheet similar to that used in the battery case 1 is widely used as the lead material 2.

[0005] On the surface 2a of the lead material 2, two welding electrodes 3, 3 each having a small diameter at the tip 3a, are arranged in parallel at a predetermined interval. Then, a predetermined pressing force is applied to the lead material 2 from the welding electrodes 3 and 3 to bring the back surface 2b of the lead material 2 and the front surface 1a of the battery container 1 into close contact. In this state, a predetermined welding current is supplied from the power supply 4. The welding current is input to the lead material 2 from one of the welding electrodes, and a part of the current is returned from the other welding electrode to the power supply 4 through the lead material 2,
The remaining welding current flows in the thickness direction of the lead material 2 around the portion located immediately below the tip 3a of the welding electrode, reaches the surface 1a of the battery case 1, and then passes through the battery case 1 to the other welding electrode. It flows in the thickness direction of the lead material 2 around the portion located immediately below the tip 3a, and returns to the power source from the other welding electrode.

In this process, Joule heat is generated at the contact interface between the back surface 2b of the lead material located immediately below each welding electrode and the front surface 1a of the battery container 1, and both members near the contact interface are partially melted. To form a nugget, and the two members are spot welded. As a result, a welded structure of the battery and the lead material in which the lead material is welded and fixed to the surface of the battery container 1 is obtained.

[0007]

The battery case is made of Ni-plated steel sheet and the lead material is made of Ni alone or N
It has been pointed out that the following problem occurs when both are made of the i-plated steel sheet and are welded by the above-mentioned parallel resistance welding method. That is, there is a problem that the welding strength between the battery container and the lead material is not so high, and the welding strength obtained for each welding operation varies.

[0008] The fact that the welding strength is not high means that when a battery pack containing the welded structure is incorporated into an electric or electronic device and actually used, for example, when those devices are dropped, the impact is caused by the impact. The device may be damaged and the function of the device may be lost. Further, when the welded structure is mounted on an electric vehicle and actually used, the welded portion is damaged by external force such as violent vibration or the like, so that the traveling is stopped.

[0009] Also, that the welding strength varies,
Generally, considering that the welding operation is continuously performed in the line process, it also means reducing the welding reliability of the manufactured battery-lead material welded structure. For this reason, efforts have been made to optimize welding conditions such as welding current and welding time and to stably obtain high welding strength, but still satisfactory results have not been obtained.

The present invention solves the above-mentioned problems in a battery-lead material welded structure obtained by resistance-welding a lead material to a battery container, particularly a battery container made of a Ni-plated steel plate, by a parallel resistance welding method. It is another object of the present invention to provide a novel battery and lead material welded structure in which a high welding strength is stably realized between a battery container and a lead material, and a method of manufacturing the same.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, the following description has been made between the surface of the battery (container) and the lead material during the parallel resistance welding. It has been found that the interposition of the organic insulating film to be performed increases the welding strength between the battery and the lead material and stabilizes it, and has developed the battery and lead material welding structure of the present invention and the method for producing the same. .

That is, in the welded structure of a battery and a lead material according to the present invention, the surface of the battery and the lead material have an organic insulating film,
For example, it is welded through a film made of any one of silicone oil, a mixture of linear hydrocarbons having 15 to 20 carbon atoms, an electrical insulating material, or a rust inhibitor, especially a film of linear silicone oil. It is characterized by. Also,
In the present invention, when the lead material is welded to the surface of the battery, an organic insulating film is formed at least on the surface of the battery or / and the surface of the lead material at a welding location, and then the battery is subjected to a parallel resistance welding method. A method for manufacturing a welded structure of a battery and a lead material, wherein a lead material is resistance-welded to a surface of the battery.

[0013]

FIG. 1 is a partially cutaway sectional view showing an example A of a welded structure of a battery and a lead material according to the present invention. In FIG. 1, the container surface 1a of the battery 1 (the bottom surface in the figure).
A battery and a lead material are welded by forming two nuggets 5 and 5 between the lead material 2 and the lead material 2.
Then, the above-described container front surface 1a and the back surface 2b of the lead material 2
Except for the nuggets 5 and 5, an organic insulating film 6 to be described later is interposed therebetween, and this is the most significant feature of the welded structure A of the present invention.

The organic insulating film 6 is interposed as an insulating layer between the surface 1a of the container and the back surface 2b of the lead material 2 to increase the resistance immediately below the welding electrode during the parallel type resistance welding, thereby energizing. The generated Joule heat is made larger or more appropriate than when the insulating film 6 is not present, thereby increasing the nuggets 5, 5 formed between the container surface 1a and the lead material 2, and as a result, high and stable It is considered that the welding strength can be realized.

The effect of the organic insulating film as described above is exerted as long as the film exists between the surface of the container and the lead material. However, when the thickness is excessively large, the insulation resistance when performing the parallel resistance welding method becomes too large, and it is difficult to form a good nugget, and the welding strength is high, although it differs depending on the type of coating material used. No. For this reason, when the film is, for example, a silicone oil film described later, the thickness of the film is preferably set to an average value of 100 nm or less. More preferably, it is 60 to 90 nm.

As a constituent material of the organic insulating film having such a function, silicone oil, for example, a mixture of linear hydrocarbons having 15 to 20 carbon atoms such as liquid paraffin,
For example, electric insulating materials such as phenol resin and alkylphenol resin modified with rosin and ester gum, or various rust preventives can be mentioned as preferable examples.

Of these, silicone oils are preferred because they have good insulation properties and have little change in viscosity over a wide temperature range and are easy to handle. In particular, dimethyl silicone oil, methylphenyl silicone oil,
Linear silicone oils such as polymethylsiloxane diol and methylhydrogen silicone oil are suitable because they are liquid at room temperature and can be easily applied to battery containers and lead materials in a manufacturing method described later.

This welded structure can be manufactured as follows. First, the constituent material of the organic insulating film is applied to the surface of the battery container or / and the surface of the lead material.
The application may be performed on the entire surface of the battery container or the lead material, or may be performed only on a portion to be welded. In this case, by appropriately diluting the constituent materials with a solvent, the composition is adjusted to an appropriate viscosity so that the coating operation can be performed smoothly, and the coating is performed. Thereafter, the coating is subjected to a drying treatment to volatilize the solvent. Is preferred. Formation of a coating film with uniform thickness,
Therefore, an organic insulating film having a uniform thickness can be formed.

The reason is that the thickness of the organic insulating film to be formed can be changed as follows. That is, a material solution having a different concentration of the constituent material may be prepared by changing the amount of the solvent, and then applied. For example, if a material solution having a high concentration of constituent materials is used, a thick film can be formed, and if a material solution having a low concentration is used, the formed film becomes thin.

Thereafter, after the lead material is disposed on a predetermined surface of the battery container, the two members may be resistance-welded by the parallel resistance welding method described above. At this time, the organic insulating film is thermally decomposed and removed by the high heat at the location where the nugget is formed, but remains between the battery container surface and the lead material at other locations, as shown in FIG. It becomes such a welding structure.

[0021]

Example 1 First, TSF451 (trade name, dimethyl silicone oil manufactured by Toshiba Silicone Co., Ltd., viscosity: about 1000 cst) was dissolved in n-hexane to prepare a plurality of diluting solutions having different concentrations of the dimethyl silicone oil. Was prepared.

On the other hand, a battery container A made of a Ni-plated steel sheet having a thickness of about 3 μm and a low-carbon steel sheet (carbon concentration: 0.05 to 0.1%) having a thickness of 0.3 mm coated on its surface.
AA size battery is prepared, and a thickness of about 3 mm is applied on the surface of a low carbon steel sheet (carbon concentration: 0.05 to 0.1%) with a thickness of 0.15 mm.
A lead material plated with μm of Ni was prepared.

At the center of the bottom surface of the battery, 10 μL of each of the diluted solutions described above was dropped, and the entire bottom surface was spread with Bencotton paper, and excess diluted solution was wiped off. Then, the mixture was allowed to stand at room temperature for about 2 hours to evaporate the solvent n-hexane, thereby forming a dimethyl silicone oil film having a different thickness on the bottom surface. The thickness of each of the obtained films was measured using a Fourier transform infrared absorption spectrometer.

Then, as shown in FIG. 7, the lead material 2 is arranged on the bottom surface 1a of each battery, and a pressure of 2.27 kgf is applied by a welding electrode (1.5 mm in diameter of the tip 3a).
The lead material 2 was welded to the battery container by performing parallel resistance welding at a welding current of 1.7 kA for 0.01 second. Then
As shown in FIG. 8, one end 2c of the lead material 2 welded to the bottom surface 4a of the battery 1 is gripped by a chuck 7, and the chuck 7 is pulled up by a tensile tester 8 to peel off the lead material 2. The test was performed. At this time, the peeling test was performed so that the angle θ formed between the lead material 2 and the bottom surface of the battery 1 was always constant, and the tensile strength by the tester 8 was increased at a constant speed. The tensile strength when the lead material 2 was completely peeled off from the bottom surface of the battery 1 was measured, and it was defined as the welding strength.

The results are shown by a black circle in FIG. 2 as a relationship diagram between the thickness of the film formed on the surface of the battery container and the welding strength. For comparison, both were welded under the same conditions as in the example, except that the lead material was resistance-welded directly to the surface of the battery container without forming a film, and the welding strength at that time was obtained. Was measured. The results are shown as ○ in the figure.

Example 2 The same specifications as in Example 1 were used except that the silicone oil used was TSF434 (trade name, methylphenyl silicone oil manufactured by Toshiba Silicone Co., Ltd., viscosity: about 200 cst). The battery and the lead material were welded, and the welding strength of both was measured.

The results are shown in FIG. FIG.
The circles in the table indicate the results of the comparative example described in Example 1. The following is clear from FIG. 2 and FIG. (1) When a silicone oil film is formed on the surface of the battery container and the lead material is resistance-welded, the welding strength is clearly improved as compared with the case where no film is formed. In addition, the variation in strength is about 0.5 to 1.5 kgf.

(2) As the thickness of the film increases, the welding strength increases. However, when the thickness exceeds 100 nm, the welding strength decreases. this is,
This indicates that the insulation resistance of the film has become too large and there is difficulty in forming the nugget. For this reason, the thickness of the film is 100 nm or less, particularly 40 to 80 nm.
It can be seen that it is preferable to set it to the degree.

Example 3 Using the diluted solution used in Example 1, dimethyl silicone oil films having different thicknesses were formed on both surfaces of the lead material used in Example 1 in the same manner as in Example 1. The thickness of the film formed on both surfaces of each lead material is the same. The above-mentioned lead material was resistance-welded to the surface of the battery container under the same conditions as in Example 1 without forming a silicone oil film on the surface of the battery container, and the welding strength in each case was measured.

The results are shown in FIG. 4 by a black circle as a relationship between the total thickness of the coatings formed on both surfaces of the lead material and the welding strength. 4 indicate the results of the comparative example shown in Example 1. Example 4 Both surfaces of a lead material were the same as in Example 3 except that the silicone oil used was YF3057 (trade name, polymethylsiloxane diol manufactured by Toshiba Silicone Co., Ltd., viscosity: about 3000 cst). A film on the surface of the battery where the film is not formed,
The welding strength of both was measured.

The results are shown in FIG. FIG.
The circles in the table indicate the results of the comparative example described in Example 1. As is clear from FIGS. 4 and 5, even when a silicone oil film is formed on the lead material, the welding strength increases as the thickness increases. However, when the total thickness of both surfaces exceeds 120 nm, the welding strength decreases. For this reason, the thickness of the film formed on the lead material is 120 nm or less, particularly 60 to 10 nm.
It can be seen that setting to about 0 nm is preferable.

Example 5 In place of dimethyl silicone oil, JIS K 90
Liquid paraffin (mixture of linear hydrocarbons having 15 to 20 carbon atoms) according to Reagent No. 03, which was diluted with acetone to prepare various dilute solutions, and the procedure was carried out except that this solution was used. In the same manner as in Example 1, the battery and the lead material were resistance-welded, and the welding strength of both was measured. FIG. 6 shows the result.

As is clear from FIG. 6, good welding strength can be obtained even when liquid paraffin is used as the coating material.

[0034]

As is apparent from the above description, the welded structure of the battery and the lead material of the present invention has an organic insulating film, preferably a silicone oil film, interposed between the battery surface and the lead material. It is manufactured by the parallel resistance welding method in a state where it is, so the welding strength between the battery surface and the lead material,
It is much higher than before.

Accordingly, even if an external force is applied to the welded structure, it is difficult for the welded portion to be damaged. For example, the welded structure can be mounted as a drive source of an electric vehicle, and its industrial application field is wide.

[Brief description of the drawings]

FIG. 1 is a partially cutaway sectional view showing an example A of a welded structure of a battery and a lead material of the present invention.

FIG. 2 is a graph showing a relationship between a coating thickness and a welding strength in Example 1.

FIG. 3 is a graph showing the relationship between the thickness of a coating and welding strength in Example 2.

FIG. 4 is a graph showing a relationship between a coating thickness and a welding strength in Example 3.

FIG. 5 is a graph showing the relationship between the thickness of the coating and the welding strength in Example 4.

FIG. 6 is a graph showing a relationship between a coating thickness and a welding strength in Example 5.

FIG. 7 is a schematic diagram for explaining a parallel resistance welding method.

FIG. 8 is a schematic diagram for explaining a method for measuring welding strength.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery 1a Battery (container) surface 2 Lead material 2a Surface of lead material 2b Back surface of lead material 2c One end of lead material 2 Welding electrode 3a Tip of welding electrode 3 4 Power supply 5 Nugget 6 Silicone oil film (organic insulation) 7) Chuck 8 Tensile tester

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kayo Arai 3-4-10 Minamishinagawa, Shinagawa-ku, Tokyo Toshiba Battery Corporation

Claims (5)

[Claims] 1. A welded structure of a battery and a lead material, wherein the surface of the battery and the lead material are welded via an organic insulating film. 2. The welded structure of a battery and a lead material according to claim 1, wherein the battery case of the battery is made of Ni-plated steel sheet. 3. The organic insulating film according to claim 1, wherein the organic insulating film is made of one of silicone oil, a mixture of linear hydrocarbons having 15 to 20 carbon atoms, an electric insulating material, and a rust inhibitor.
Battery and lead material welded structure. 4. The welded structure of a battery and a lead material according to claim 1, wherein said organic insulating film comprises a linear silicone oil. 5. When welding a lead material to a surface of a battery,
After forming an organic insulating film on at least the surface of the battery or / and the surface of the lead material at the welding location, the lead material is resistance-welded to the surface of the battery by a parallel resistance welding method. Method of manufacturing a welded structure of a material.