Patent Application
20080096105
These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.
As illustrated in
The electrode assembly 150 has a stacked structure. The first and second electrode plates 110 and 120 are respectively coated with a positive active material and a negative active material. The separator 130 is interposed between the first and second electrode plates 110 and 120, to enable the movement of lithium ions while preventing a short circuit therebetween. The stacked structure is spirally wound. Electrode tabs 141 and 143 extend from the first and second electrode plates 110 and 120, respectively. The first electrode plate 110 may serve as a positive electrode, and the second electrode plate 120 may serve as a negative electrode.
A chalcogenide compound can be used as the positive electrode active material coated on the first electrode plate 110. For example, the positive electrode active material may be a composite metal oxide, such as, LiCoO2, LiMn2O4, LiNiO2, LiNi1-xCoxO2 (0<X<1), or LiMnO2.
The negative electrode active material, coated on the second electrode plate 120, can be, for example, a carbon-based material, Si, Sn, a tin oxide, a composite tin alloy, a transition metal oxide, or a lithium metal oxide. In general, the positive electrode plate is formed of aluminum, and the negative electrode plate is formed of copper. The separator is generally formed of polyethylene (PE) or polypropylene (PP), but the invention is not limited to the above-mentioned materials.
The case 210 has a space defined therein. The deep drawing portion 210a has a predetermined depth, to allow the electrode assembly 150 to be disposed therein. The case 210 has a flange 210b that is formed around the deep drawing portion 210a, to cover the deep drawing portion 210a. The case 210 is formed of a soft material, for example modified polypropylene, such as cast polypropylene (CPP). The case 210 includes an aluminum film and an adhesive layer disposed on one surface of the aluminum film. The case includes an insulating film that is formed on the other surface of the aluminum film. The insulating film is made of a resin material, such as, nylon or polyethylene-terephthalate (PET).
The first and second electrode tabs 141 and 143 are connected to the electrode assembly 150 and extend from the case 210 by a predetermined length. The bare cell 200, formed by putting the electrode assembly 150 into the case 210, is connected to a protection circuit board 170. The protection circuit board 170 is electrically connected to the electrode assembly 150. The protection circuit board 170 is to break the flow of current when the battery is erroneously operated.
An insulating member 160 is disposed upon the first and second electrode tabs 141 and 143 and extends from the case 210 to the outside. The protection circuit board 170 is electrically connected to the first and second electrode tabs 141 and 143, with the insulating member 160 interposed therebetween. The protection circuit board 170 is electrically connected to an external terminal 180 exposed to the outside through a connecting lead 171. The external terminal 180 is directly connected to an external electric terminal during charging.
The first and second outer cases 310 and 320 have main surfaces 312 and 322, lateral surfaces 314 and 324 that are bent from the edges of the main surfaces 312 and 322 at right angles, and bottom surfaces 316 and 326 that are bent from lower parts of the main surfaces 312 and 322 and the lateral surfaces 314 and 324, respectively.
The outer case 300 has a recessed portion 510 disposed at an end, for example a bottom end, thereof. As used herein, the “bottom end” refers to a lower portion of the outer case as depicted in the drawing. However, a “bottom”, a “bottom end”, and a “bottom cover” as referred to herein, are used for convenience and can relate to either end of an apparatus. The recessed portion 510 has a perimeter that is less than a perimeter of the outer case 300 itself. Step portions 318 are formed at lower portions of the first outer case 310. The step portions 318 are disposed at the boundaries between the main surface 312, the lateral surface 314, and the bottom surface 316. Step portions 328 are formed at lower parts of the second outer case 320. The step portions 328 are boundaries between the main surface 322, the lateral surface 324, and the bottom surface 326. The step portions 318 and 328 can be disposed adjacent to one another to form the recessed portion 510. The step portions 318 and 328 reduce the length of the bottom surfaces 316 and 326 to less than the widths of the main surfaces 312 and 322, and the step portions 318 and 326 and reduce the widths of the bottom surfaces 316 and 326, to less than the widths of the lateral surfaces 314 and 324.
The first and second outer cases 310 and 320, of the outer case 300, can be formed of a corrosion-resistant material, for example, stainless steel or plastic, but the material forming the first and second outer cases 310 and 320 is not limited thereto.
The outer case 300 forms the majority of the external surface of the battery pack 500, with an upper surface 205 of the bare cell 200 connected to the protection circuit board 170, and a lower surface 206 of the bare cell 200 is disposed in opposition to the upper surface 205. The upper and lower surfaces 205 and 206 are molded from a resin material, by a hot-melting method.
In this way, the resin material is filled into the step portions 318 and 328, formed at the lower portion of the outer case 300, to form the bottom cover 400. The step portions 318 and 328 of the outer case 300 serve as coupling portions for stably coupling with the bottom cover 400.
As described above, the molding of the bottom cover 400 is performed by filling the step portions 318 and 328, of the outer case 300, with a resin material. That is, since the bottom cover 400 is coupled to the step portions 318 and 328, so as to surround the lower part of the outer case 300, the bottom cover 400 is strongly coupled to the bare cell 200 and the outer case 300.
In the above-described embodiment, a pouch-shaped case has been described, but the invention is not limited thereto. For example, the bare cell may be put into a square-shaped outer case, and the bottom cover may be coupled to the square-shaped outer cover. In this case, the same effects and operations as described above are also obtained.
As described above, according to the battery pack according to the embodiment of the invention, a resin material is filled into lower portions of the outer case, to form a bottom cover having a perimeter equal to less than the perimeter of the outer case, and the bottom cover is molded to the outer case so as to reduce the overall thickness of the battery pack.
Further, according to the above-described embodiment of the invention, the bottom cover is coupled to the outer case so as to fill up the step portions formed at the lower parts of the outer case, which makes it possible to prevent the bottom cover from being easily detached from the bare cell and the outer case. Thus, the bottom cover is strongly fixed to the bare cell and the outer case.
Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-103370 | Oct 2006 | KR | national |
