JP2000260399A - Cylindrical battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical battery capable of spot-welding a conductor foil with high reliability to the outer bottom wall surface of the battery. SOLUTION: The cylindrical battery has a cylindrical battery can 3 with bottom serving as one electrode terminal and whose one end is opened; a battery element inserted into the cylindrical battery can 3; and a sealing cover 4 for introducing the other electrode terminal 5 connecting to the battery element and liquid-tightly sealing the opening of the cylindrical battery can 3, and the outer bottom wall surface of the cylindrical battery can 3 is expanded outward.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical battery, and more particularly, to a cylindrical battery suitable for a pack battery.

[0002]

2. Description of the Related Art In portable electronic devices, a plurality of charge / discharge type rechargeable batteries are housed in an insulating outer case as a drive power source in terms of high output or high functionality. -A sealed battery pack is used. The plurality of secondary batteries housed / sealed in the insulating outer case adopt a configuration in which they are electrically connected in series or in parallel, and the battery terminals of the housed / sealed secondary battery group are provided. However, a configuration is employed in which an insulating outer case is connected to an external connection terminal that is embedded and inserted.

FIG. 2 is a top view showing an example of an electrical connection configuration of cylindrical batteries constituting this type of battery pack. 2, 1a, 1b, 1c,... Are cylindrical batteries, 2a, 2b,.
Are conductive foils for connecting the cylindrical batteries 1a, 1b, 1c,..., And the conductive foils 2a, 2b,.
are electrically and mechanically joined to the electrode terminal surfaces b, 1c,... by spot welding.

For example, conductive foils 2a, 2b,... Having a thickness of about 0.1 to 0.4 mm and a width of about 3 to 10 mm are formed on the outer bottom surface of a cylindrical can forming one electrode of cylindrical batteries 1a, 1b, 1c,. Are arranged in contact with each other, and a welding electrode is brought into contact with and pressurized to a portion to be joined, and is performed by a so-called series spot welding method.

[0005]

However, when the cylindrical batteries are electrically connected by the series spot welding described above, the following problems may occur. That is, spot welding is performed on the premise of a pressing force, a current, and an energizing time, but further depends on the tip shape and abrasion state of the welding electrode, or the material and state of the portion to be welded.

[0006] In the case of a cylindrical battery, the cylindrical can forming one electrode is generally as thin as about 0.2 to 0.4 mm. Tends to occur.

More specifically, when a welding electrode is normally contacted and pressed against the outer bottom surface of a cylindrical can having a flat surface with a conductive foil 2a or the like, the outer bottom surface of the cylindrical can is Due to the recess (depression), the correspondence with the shape of the tip of the welding electrode is broken (uniform contact cannot be ensured). As a result, the current path surface is reduced, and as a result, the current density is increased, which not only causes a splash where the molten portion explodes, but also lowers the tensile strength of the joint portion, thereby improving the connection reliability. There is a problem that is easily damaged.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a cylindrical battery capable of highly reliable spot welding of a conductive foil to an outer bottom wall surface of a battery.

[0009]

According to the first aspect of the present invention, there is provided a bottomed cylindrical battery can having one open end forming one electrode terminal, a battery element provided in the cylindrical battery can, and the battery. A sealing lid for liquid-tightly leading out the other electrode terminal connected to the element and sealing the opening of the bottomed cylindrical battery can in a liquid-tight manner. A cylindrical battery wherein the bottom wall surface of the bottom cylindrical battery can is bulged outward.

In the first aspect of the present invention, the cylindrical battery comprises:
For example, single type, AA type, AA type, AAA type, etc.
Generally, it has a configuration provided with a bottomed cylindrical battery can having a wall thickness of about 0.2 to 0.4 mm. The bottomed cylindrical battery can has a configuration in which the bottom wall surface is bulged outward.
That is, the cylindrical battery can usually has a flat bottom wall surface, but the present invention is characterized in that at least a substantially central portion is bulged more than the side wall end.

Here, the bulging of the bottom wall surface of the cylindrical battery can to the outside is limited to a hemispherical or convex shape as long as the essential function and compactness of the battery can are not impaired. The form is taken. And, by bulging the bottom wall surface outward, deformation (denting) of the bottom wall surface can be prevented or avoided against pressure welding of the welding electrode.
In addition, the degree of bulging of the bottom surface of the cylindrical battery can for the purpose of such effects differs depending on the standard / type, material, and wall thickness of the cylindrical battery can. In the case of a cylindrical can for a single type battery, it is sufficient that the cylindrical can protrudes by about 15 to 50 μm from the end of the side wall.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described below with reference to FIG.

FIG. 1 is a side external view showing a main part of a cylindrical battery according to an embodiment. In FIG. 1, reference numeral 3 denotes a cylindrical battery can enclosing a battery element, and 4 denotes an airtight and electrically insulated sealing of the opening of the cylindrical battery can 3 after the battery element is sealed in the cylindrical battery can 3. It is a sealed body stopped. here,
The cylindrical battery can 3 is formed by drawing a stainless steel thin plate having a thickness of, for example, about 0.25 mm, and the outer bottom wall 3a of the cylindrical battery can 3 is attached to one electrode of the battery element.
They are electrically connected to form an electrode terminal (for example, a negative electrode). And the outer bottom wall surface of the cylindrical battery can 3 forming one electrode terminal
3a has a configuration swelling about 20 μm.

The sealing body 4 is air-tightly or liquid-tightly caulked to the opening of the cylindrical battery can 3 via an insulating shield ring, and the other electrode of the sealed battery element. Terminal (eg positive electrode) 5 electrically connected to
Is insulated.

[0015] Ten cylindrical batteries of the above construction are prepared, and an aluminum foil having a thickness of about 50 µm and a width of about 10 mm is brought into contact with a bottom wall 3a forming one electrode terminal of each cylindrical battery. , A welding electrode was pressed onto the bottom wall surface 3a of the cylindrical battery, so-called spot welding was performed, and aluminum foil was electrically bonded to the outer bottom wall surface 3a of the cylindrical battery.
The electrical joining of the aluminum foil to the outer bottom wall 1a of the cylindrical battery was made well without variation. Also,
When the tensile strength of the joint was measured,
Maximum 5.34 kgf, minimum 3.90 kgf, average 4.72 kgf,
A highly reliable bond that was not likely to come off due to an impact or the like was formed.

Further, 10 cylindrical batteries were manufactured under the same conditions except that the outer bottom wall 3a of the cylindrical battery can 3 was expanded by about 40 μm in the above configuration, and the same test was performed.・ Evaluation was conducted. Also in this case, the electrical joining of the aluminum foil to the bottom wall 3a of the cylindrical battery was made well without variation.

When the tensile strength of the joint was measured, the maximum value was 5.91 kgf, the minimum value was 4.09 kgf,
With an average value of 4.92 kgf, a highly reliable joint was formed without any risk of detachment due to impact or the like.

As described above, the fact that the foil-like conductor can be joined mechanically and electrically with high reliability to the outer bottom wall surface 3a of the cylindrical battery is required for the assembled and configured battery pack.
Even if it receives an external force such as an impact, the possibility of damaging the electrical connection of the built-in cylindrical battery is largely eliminated. The improvement / improvement of the impact resistance also contributes to the improvement of the reliability of the drive power supply, as well as the provision of mechanical durability of the battery pack. On the other hand, for comparison, in the configuration of the cylindrical battery, the bottom wall 3a of the cylindrical battery can 3 was made flat (Comparative Example 1) or the outer bottom wall 3a of the cylindrical battery can 1 was formed.
Were made to have a concave surface of about 20 μm (Comparative Example 2), and 10 cylindrical batteries were produced under the same conditions, and similar tests and evaluations were performed.

Also in the case of these comparative examples, the size of the bonding surface to the outer bottom wall 3a of the aluminum foil cylindrical battery was found to vary. Then, when the tensile strength of each of the joints was measured, in the case of Comparative Example 1, the maximum value was 5.30 k.
gf, minimum value 3.75 kgf, average value 4.46 kgf, and Comparative Example 2
In the case of, the maximum value is 4.72 kgf, the minimum value is 3.20 kgf, the average value is 4.
It was 40 kgf. That is, in the case of Comparative Examples 1 and 2, the dispersion of the tensile strength of the joint was large, and the tensile strength was low as a whole, so that the joints could be detached by impact or the like.

The present invention is not limited to the embodiments, and various modifications can be made without departing from the gist of the invention. For example, the cylindrical battery may be of a type other than a single type, and the thickness and material of the cylindrical battery can can be appropriately selected according to the application and the standard.

[0021]

According to the first aspect of the present invention, a foil-shaped or thin-plate conductor is welded to the bottom wall surface of a cylindrical battery by a series spot or the like. When brought into contact, the contact and pressurization at the tip of the welding electrode are transmitted uniformly. That is, a large path for the welding current is ensured, and local concentration of the current density is avoided, so that a favorable fused portion is easily formed.

The fact that the above-mentioned good fusion zone can be formed increases the tensile strength of the junction, thereby improving the reliability of mechanical and electrical junctions. Therefore, when assembled and configured in a battery pack, it is easy to perform attachment / detachment and handling operations on corresponding devices, and a battery pack with high reliability is provided.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration example of a main part of a cylindrical battery according to the present invention.

FIG. 2 is a top view showing an electrical connection configuration of a cylindrical battery in the battery pack.

[Explanation of symbols]

 3. Cylindrical battery can that also serves as one electrode terminal 3a: Outer bottom wall surface (bulge) of cylindrical battery can 4. Sealing body 5. Other electrode terminal from which sealing body is led out

Claims (1)

[Claims] A bottomed cylindrical battery can having one end forming an electrode terminal; a battery element provided in the cylindrical battery can; and a second electrode terminal connected to the battery element is liquid-tight. And a sealing lid for sealing the opening of the bottomed cylindrical battery can in a liquid-tight manner, wherein the bottom wall surface of the bottomed cylindrical battery can is outward. A cylindrical battery characterized by being bulged to the bottom.