JPH11170069A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a square battery for which lead connection is easily made to its square case formed with aluminum. SOLUTION: The square battery is constituted by storing a power generating element in a square case 1 formed with aluminum in a shape of a square cylinder with a bottom and by hermetically sealing the open end with a sealing plate 2. In making an electrical connection with a rivet 5 provided on the sealing plate 2 as the negative electrode terminal and with the square case 1 as the positive, a clad material 4 is ultrasonically welded in which an aluminum plate and a stainless steel plate are cladded on the bottom of the square case 1, for the purpose of facilitating lead connection for the square case 1 formed with aluminum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery having a power generating element such as a lithium ion secondary battery housed in an aluminum case, and more particularly to a battery which facilitates electrical connection to an aluminum case serving as an electrode portion. It is about.

[0002]

2. Description of the Related Art For example, a secondary battery used as a power source of a portable electronic device is required to have a high energy density, and at the same time, to have a shape that is efficient in space use for weight reduction and size reduction. Have been. A lithium-ion secondary battery using a square aluminum case as a battery that meets these requirements is in the spotlight.

[0003] Since this lithium ion secondary battery is required to have a stable sealing property for a long period of time even from the viewpoint of its structure, a sealing plate is joined to the opening end of the bottomed square case by laser welding to seal the opening end. . A rivet serving as a negative electrode terminal is attached to the sealing plate in a manner insulated from the sealing plate, and the positive and negative electrode terminals of the battery are configured using the rectangular case as a positive terminal.

It is necessary to connect leads to the positive and negative electrode terminals in order to make electrical connection to equipment using a battery. However, when the rectangular case is formed of an aluminum material, resistance welding or soldering is required. Since it is difficult to attach, a structure in which a metal plate that is easily connected to a lead is joined to a rectangular case is employed. The aluminum plate and the nickel plate clad and joined to each other by ultrasonic welding to the bottom surface of the rectangular case as the metal plate facilitate resistance welding or soldering of the lead to the nickel plate. For example, Japanese Patent Application Laid-Open No. 9-320565 discloses the use of such a lead. However, this is not enough, and when the thickness of the aluminum plate in the clad material is not sufficiently thicker than that of the nickel plate, there is a problem that the bonding state between the lead plate and the case is not sufficient.

[0005]

In order to connect the lead to the rectangular case, means for resistance welding the lead to the nickel plate of the clad material are often used. It needs to be done promptly so as not to affect. Therefore, there is a demand for a material having better weldability in resistance welding or a material that is less likely to exert a thermal effect than the nickel plate.

An object of the present invention is to provide a battery capable of easily connecting leads to a battery case made of an aluminum material.

[0007]

In order to achieve the above object, according to the present invention, a power generating element is housed in a battery case having a bottomed cylindrical shape made of an aluminum material, and the open end of the battery case is sealed by a sealing plate. In a hermetically sealed battery, a stainless steel plate and an aluminum plate are joined to the bottom surface of the battery case, and the thickness of the aluminum plate is 2 times the thickness of the stainless steel plate.
The clad material having a size of twice or more is joined by ultrasonic welding with the aluminum plate side facing the battery case side.

[0008] Although the battery case serving as the positive electrode terminal of the battery is made of aluminum material, it is difficult to make a lead connection. However, since the clad material is bonded to the bottom surface of the battery case, the stainless steel plate forming the clad material is used. The lead can be easily resistance welded or soldered. Since the stainless steel material has low thermal conductivity, the heat at the time of lead connection by resistance welding or the like is not easily transmitted to the battery case, so that thermal influence is suppressed. In addition, stainless steel has high electrical resistance and therefore has excellent weldability in resistance welding.
Lead connection by resistance welding can be quickly and reliably performed.

In particular, the thickness of the aluminum plate constituting the clad material in the above configuration is 2 times the thickness of the stainless steel plate.
The thickness of the stainless steel plate must be the minimum necessary by being formed more than twice, and the thickness of the aluminum plate necessary for joining the clad material to the aluminum battery case by ultrasonic welding should be secured. Can be.

[0010] Further, by ultrasonically welding the clad plate to the case bottom surface, the clad material can be easily joined to the aluminum plate.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.

FIG. 1 shows a configuration of a prismatic battery according to the present embodiment. The prismatic battery accommodates a power generating element in a prismatic case 1 in which an aluminum material is formed in a bottomed prismatic tubular shape, and has an open end thereof. The inside of the rectangular case 1 is hermetically sealed by laser-welding the sealing plate 2. A rivet 5 made of nickel-plated iron is attached to the sealing plate 2 so as to be insulated from the sealing plate 2, connected to a power generating element to serve as a negative electrode terminal of the battery, and the square case 1 serves as a positive electrode terminal. Electrodes are formed. Therefore, the electrical connection to equipment that uses this prismatic battery as a power supply is:
Lead connection is made to the rectangular case 1 and the rivet 5. Since the rivet 5 is made of nickel-plated iron as described above, it is easy to join the leads by resistance welding or the like, but it is difficult to perform resistance welding or soldering to the rectangular case 1 made of aluminum. A clad material 4 is ultrasonically welded to the bottom surface of the rectangular case 1 in order to easily perform lead joining to the rectangular case 1.

The clad material 4 is, as shown in FIG.
The aluminum plate 4a and the stainless steel plate 4b are formed by clad bonding. The aluminum plate 4a is bonded to the square case 1 by ultrasonic welding with the aluminum plate 4a side facing the square case 1. The clad material 4 in the present embodiment has an aluminum plate 4a having a thickness of 0.2 mm and a stainless steel plate 4b.
Is formed to have a thickness of 0.05 mm, but it is desirable that this thickness ratio is formed so that the aluminum plate 4a is at least twice as large as the stainless steel plate 4b. Stainless plate 4b
Can easily perform resistance welding and soldering, so that lead connection to the square case 1 is easy, and since stainless steel has low thermal conductivity, heat during lead welding is difficult to be conducted to the square case 1 side. It is possible to suppress a thermal influence inside. Also, the aluminum plate 4a
Is brought into contact with the rectangular case 1 formed of an aluminum material, an ultrasonic welding point is applied to the stainless steel plate 4b, and ultrasonic vibration is applied, so that the aluminum plate 4a and the rectangular case 1 are ultrasonically welded. Welding is performed between aluminum homogenous materials, and welding is reliably performed. FIG.
The plurality of recesses 9 shown in (c) are contact traces of the ultrasonic welding points.

The clad material has a thickness of 0.2 mm as described above.
The aluminum plate and the stainless steel plate with a thickness of 0.05mm were used for bonding, but when joining to the aluminum case by ultrasonic welding, the ratio of the thickness of this aluminum plate to the stainless plate can greatly affect the bonding strength. all right. Although the reason is not clear, it is considered as follows.

Ultrasonic welding is a method of applying vibration to a contact point and joining materials by frictional heat. At this time, it is considered that the closer the environment such as the temperature around the contact point and the heat transfer / heat storage, the stronger the bonding. Therefore, it is most desirable that the contacts be made of the same material. Considering the clad material of the present application from the above viewpoints, it is a material in which a metal having relatively high thermal conductivity such as aluminum and a metal having relatively low thermal conductivity such as stainless steel are bonded together. When welding aluminum and aluminum, it is expected that the stainless steel will affect the environment such as heat transfer and heat storage of the weld, depending on the conditions. That is, in the present application, the state of the aluminum on the case side and the aluminum on the clad material side to be welded are different from each other, and this is considered to greatly affect the bonding strength. From the above, it is considered that the bonding strength increases when the thickness of the aluminum plate is larger than the thickness of the stainless steel plate. FIG. 3 shows the results of measuring the bonding strength between the clad material and the case while changing the thickness ratio between the aluminum part and the stainless steel part. From the figure, it can be seen that when the ratio of the thickness of aluminum to the thickness of stainless steel is 2 or more, the bonding strength sharply increases.

Therefore, the clad material of the present invention preferably has a thickness of aluminum> thickness of stainless steel, and the ratio is more preferably 2 or more.

FIG. 4 shows an example in which leads are connected to the positive and negative electrode terminals of the rectangular battery having the above-described configuration to form a battery pack.

As shown in FIG. 4, one end of a negative electrode lead 6 is resistance-welded to a rivet 5 serving as a negative electrode terminal, and one end of a positive electrode lead 7 is resistance-welded to a cladding material 4 serving as a positive electrode terminal, thereby connecting the positive and negative electrodes. Drawer, negative electrode lead 6 and positive electrode lead 7
By connecting a circuit board 8 constituting a charge control circuit to each other end, a battery pack having a charge control circuit is formed.

[0019]

As described above, according to the present invention, since the clad material in which the stainless steel plate and the aluminum plate are joined to the bottom surface of the rectangular case is joined, the lead is connected to the square case serving as the positive electrode terminal. In this case, a stainless steel plate that can be easily subjected to resistance welding or soldering can be used, and a prismatic battery with easy lead connection can be provided.

[Brief description of the drawings]

FIG. 1A is a front view, FIG. 1B is a plan view, FIG. 1C is a bottom view, and FIG.
(D) is a side view.

FIG. 2 is a sectional view showing a configuration of a clad material.

FIG. 3 is a graph showing a correlation between a thickness ratio between an aluminum part and a stainless steel part of a clad material and a bonding strength with a case.

FIG. 4 is a perspective view showing an example in which a lead battery is connected to a prismatic battery to form a battery pack.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Square case 2 Sealing plate 4 Clad material 4a Aluminum plate 4b Stainless plate

Continued on the front page (72) Inventor Takashi Takeuchi 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kikuo Senoo 1006 Odaka Kadoma Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A battery in which a power generation element is housed in a case in which an aluminum material is formed in a bottomed cylindrical shape, and an open end of the case is hermetically sealed by a sealing plate. A battery comprising: a plate; and a clad material having an aluminum plate having a thickness of at least twice the thickness of a stainless steel plate, and ultrasonic bonding with the aluminum plate side as a case side.