Lithium ion battery

The present invention provides a lithium ion battery including a battery can, a battery cell received in the battery can, electrolyte filled in the battery can, and a battery cover sealing the battery can. The battery can is formed with a flange portion, and the battery cover is formed with a skirt portion corresponding to the flange portion. The skirt portion of the battery cover tightly wraps the flange portion of the battery can, and the skirt portion and the flange portion wrapped in the skirt portion are tightly wound and bent to the battery can, so as to realize desirable sealing between the battery can and the battery cover.

CROSS-REFERENCE TO RELATED APPLICATION

The present patent invention claims priority to Chinese Patent Application No. CN 201020669355.7 filed on Dec. 20, 2010, which is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention generally relates to lithium ion batteries and, more particularly, relates to a lithium ion battery which has desirable sealing performance and can be assembled quickly.

BACKGROUND OF THE INVENTION

Recently, with development of science and technology, portable electronic devices, such as video cameras, laptop personal computers, portable DVDs and personal digital assistants are becoming increasingly popular in people's daily life. As a desirable power source for portable electronic devices, lithium ion batteries are widely used due to high energy density, high working voltage and long life span. At present, lithium ion batteries have gradually substituted other traditional batteries and have been widely used in aircrafts, vehicles and medical equipments.

Generally, a lithium ion battery typically includes a battery can, a battery cell received in the battery can, electrolyte filled in the battery can and a battery cover sealing the battery can. In the prior art, the battery cover is typically assembled to the battery can via laser soldering for sealing the same. However, sealing the battery can and the battery cover via laser welding has the following disadvantages. The battery cover cannot be soldered onto the battery can via laser soldering quickly and the production efficiency is undesirable. At the same time, in the laser soldering procedure, defects may be introduced into the soldering area, especially when the battery cover does not tightly contact the battery can or when impurity is introduced at the soldering area, which may adversely affect sealing performance of the lithium ion battery.

What is needed, therefore, is to provide a lithium ion battery which has desirable sealing performance and can be assembled quickly.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a lithium ion battery which has desirable sealing performance and can be assembled quickly.

According to one embodiment of the present invention, a lithium ion battery includes a battery can, a battery cell housed in the battery can, electrolyte filled in the battery can, and a battery cover sealing the battery can. The battery can is formed with a flange portion and the battery cover is formed with a skirt portion corresponding to the flange portion. The skirt portion of the battery cover tightly wraps the flange portion of the battery can, and the skirt portion together with the flange portion wrapped in the skirt portion are tightly wound and bent toward the battery can, so as to provide desirable sealing performance between the battery can and the battery cover.

According to one embodiment of the present invention, the lithium ion battery not only has desirable sealing performance between the battery can and the battery cover, but also can be assembled quickly. Test result shows that, assembling a battery cover to a battery can only needs about 0.08 second.

Preferably, the battery can and the battery cover are made from same material.

Preferably, the battery can and the battery cover are both made from steel or aluminum material.

Preferably, the battery can and the battery cover have round or square cross section.

Preferably, a filling material layer is sandwiched between the flange portion of the battery can and the skirt portion of the battery cover.

Preferably, the filling material layer is made from plastic or rubber which does not react with the electrolyte.

Preferably, the filling material layer is made from fluoroplastic, fluororubber or polypropylene plastic.

Preferably, length of the filling material layer is less than width of the flange portion of the battery can.

Preferably, the filling material layer has a thickness of less than 2 mm.

According to another embodiment of the present invention, a method for assembling a battery cover to a battery can is provided. The method includes the steps of: providing a battery can having a flange portion at an upper side thereof; providing a battery cover having a skirt portion; positioning the skirt portion on the flange portion, with outer edge of the skirt portion extending out of outer edge of the flange portion; bending the skirt portion toward the flange portion so that the skirt portion wrap the flange portion; and winding and bending the skirt portion together with the flange portion wrapped in the skirt portion to the battery can, to realize desirable sealing between the battery can and the battery cover.

Preferably, the battery can and the battery cover are both made from steel or aluminum material.

Preferably, the method further includes a step of providing a filling material layer sandwiched between the flange portion of the battery can and the skirt portion of the battery cover.

Preferably, the filling material layer is made from fluoroplastic, fluororubber or polypropylene plastic which does not react with the electrolyte.

Preferably, length of the filling material layer is less than width of the flange portion of the battery can.

Preferably, the filling material layer has a thickness of less than 2 mm.

Other advantages and novel features will be drawn from the following detailed description of preferred embodiment with the attached drawings, in which:

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIGS. 1 to 3, a lithium ion battery according to one embodiment of the present invention includes a battery can10, a battery cell40received in the battery can10, electrolyte filled in the battery can10, and a battery cover20sealing the battery can10.

The battery can10is made from aluminum or steel material. The battery can10has a round, square or other suitable cross section. In the illustrated embodiment, the battery can10is formed with a flange portion102which extends out from an upper side of the battery can10.

The battery cover20is made from the same material as that of the battery can10. According to one embodiment of the present invention, the battery cover20is made from aluminum or steel material. The battery cover20has a shape and size corresponding to the shape and size of the battery can10. The battery cover20is formed with a skirt portion202at a periphery of the battery cover20, corresponding to the flange portion102of the battery can10. In assembly, when the battery cover20is positioned on the battery can10, the skirt portion202can be deformed downwardly to fully wrap the flange portion102of the battery can10.

To improve the sealing performance between the battery can10and the battery cover20, a filling material layer30is sandwiched between the battery can10and the battery cover20. The filling material layer30has a length less than a width of the flange portion102of the battery can10. The filling material layer30has a thickness of less than 2 mm. According to one embodiment of the present invention, the filling material layer30is made from material which does not react with the electrolyte and which also has desirable deformability. According to one embodiment of the present invention, the filling material layer30is made from plastic or rubber which does not react with the electroltye, such as, polypropylene plastic, fluoroplastic or fluororubber.

Referring toFIG. 1toFIG. 3, assembly of the lithium ion battery according to embodiment of the present invention will be detailed in detail. It should be noticed that, for the sake of clarity,FIG. 1only illustrates part of the battery can10, the battery cover20and the filling material layer30. The method for assembling a lithium ion battery includes the steps of: positioning the battery cell40in the battery can10; filling the electrolyte into the battery can10; positioning the battery cover20on the battery can10, with the filling material layer30sandwiched between the battery cover20and the battery can10; downwardly bending the skirt portion202of the battery cover20toward the flange portion102of the battery can10, so that the skirt portion202can tightly wrap the flange portion102of the battery can10; and tightly winding and bending the flange portion102together with the skirt portion202wrapping the flange portion102to the battery can10, so that the filling material layer30sandwiched between the battery can10and the battery cover20deforms and fills the space between the battery cover20and the battery can10and, therefore, achieves desirable sealing performance between the battery can10and the battery cover20.

In view of the foregoing description, the lithium ion battery according to one embodiment of the present invention not only has desirable sealing performance between the battery can10and the battery cover20, but also can be assembled quickly. Test result shows that, assembling a battery cover to a battery can only needs about 0.08 second.

While the present invention has been illustrated by the above description of the preferred embodiment thereof, while the preferred embodiment has been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such details. Additional advantages and modifications within the spirit and scope of the present invention will readily appear to those ordinary skilled in the art. Consequently, the present invention is not limited to the specific details and the illustrative examples as shown and described.