1. Field of the Invention
The present invention relates to a lithium rechargeable battery that has an internal space formed between a can and an electrode assembly to improve electrolyte injection.
2. Description of the Prior Art
In general, a rechargeable battery may be charged and discharged, in contrast to a nonrechargeable battery which is not rechargeable, and can be made in a compact size with a large power storage capacity. Typical examples of rechargeable batteries include nickel metal hydrogen (Ni-MH) batteries, lithium (Li) batteries, and lithium ion batteries. Recently developed lithium rechargeable batteries are widely used in cutting-edge electronic devices such as cellular phones and laptop computers.
Rechargeable lithium batteries are classified into lithium ion batteries that use a liquid electrolyte and lithium polymer batteries that use a polymer electrolyte. Rechargeable batteries may also be classified into cylindrical batteries that use a cylindrical aluminum can, rectangular box batteries that use a rectangular box-shaped aluminum can, and pouch-type batteries that are contained in a plate-shaped pouch case.
A rechargeable battery generally comprises a can, an electrode assembly contained in the can, and a cap assembly that is coupled to the top opening of the can. The electrode assembly is formed by winding a first electrode and a second electrode together with a separator interposed between them into a jelly roll. The electrode assembly is placed into the can, the top opening of which is then sealed by the cap assembly.
FIG. 1 is a top view of a conventional rectangular box type rechargeable battery with angled corners and FIG. 2 is a top view of a rectangular box type rechargeable battery with rounded corners.
Referring to FIG. 1, a can 10 generally has angled corners, a rectangular box-shaped space, and an electrode assembly 12 contained therein. However, the corners of the rectangular box type rechargeable battery shown in FIG. 1 are angled and do not accurately correspond to the corners of the electrode assembly 12, which are rounded. As a result, the can 10 has an unnecessary void that is not occupied by the electrode assembly 12. This makes it difficult to maximize the battery capacity and degrades the aesthetic appearance. In order to solve this problem, a rectangular box type rechargeable battery that has a can 20 with rounded or curved corners as shown in FIG. 2 have recently been used.
Referring to FIG. 2, the can 20 generally has curved corners, a rectangular box-shaped space, and an electrode assembly 22 contained therein together with an electrolyte (not shown). The curved corners of the can 20 accurately correspond to the curved portions of the jelly roll-shaped electrode assembly 22. As a result, unnecessary space is not created in the sides of the can 20.
However, since there is no space between the electrode assembly 22 and the can 20 in the rechargeable battery with curved corners as shown in FIG. 2, it takes a long time to inject an electrolyte and the productivity of the battery deteriorates. Furthermore, the lack of space between the can 20 and the electrode assembly 22 makes it difficult to uniformly inject the electrolyte into the electrode assembly 22. This decreases the battery's power storage capacity.