Patent Application
20100104940
The present invention relates to lithium ion batteries and, more specifically, to a battery pack for lithium ion battery cells.
Lithium ion batteries are widely used as a power source in various portable electronic devices, such as personal laptop computers, mobile phones and personal digital assistants due to high energy density, high working voltage and long life span.
Typically, a conventional battery pack for packing a lithium ion battery cell includes two layers of packing foils, i.e. an inner aluminum foil directly contacting the electrode group and the electrolyte of the lithium ion battery and an outer plastic housing or other packing materials having desirable strength for enclosing the inner aluminum foil, for instance, a thin steel strip or a metal laminate.
Chinese patent application number CN 200720050592.3 discloses a battery pack for lithium ion battery cells as previously discussed. More specifically, the inner aluminum foil directly contacting the electrode group of the lithium ion battery includes three layers of laminates, i.e. an inner polypropylene layer acting as bonding layer, an intermediate aluminum layer and an outer nylon layer acting as protective layer from inside to outside.
However, the aluminum layer does not have strength high enough to protect the electrode group and the electrolyte received therein. To provide the packaged battery cell with desirable strength, there is need to add an additional protective layer.
The above mentioned battery pack do have strength high enough to protect the electrode group and electrolyte received therein. However, the two layers structure of the battery pack will inevitably increase the total volume of the battery cell and reduce the energy density of the lithium ion battery.
One objective of the present invention is to provide a battery pack having desirable strength for lithium ion battery cells.
According to one embodiment of the present invention, a battery pack for lithium ion battery cells includes an inner bonding layer, an intermediate stainless steel layer and an outer protective layer.
Preferably, the inner bonding layer is a polypropylene layer.
Preferably, the outer protective layer is a polyester layer.
Preferably, the outer protective layer is a polyethylene terephthalate layer.
Due to the arrangement of the intermediate stainless steel layer, the battery pack for lithium ion battery cells according to one embodiment of the present invention has desirable strength and high energy density and, therefore, there is no need to add an additional protective layer to improve the strength and energy density of the lithium ion battery cell.
Other advantages and novel features will be drawn from the following detailed description of preferred embodiments with the attached drawings, in which:
Referring to
During the packaging of the battery cell, the polypropylene layer 12 directly contacts the electrode group 18 and the electrolyte 20 received therein. The polypropylene layer 12 can be bonded to the electrode group 18 via thermal melting, so as to ensure the stability and sealing effect of the packed battery cell. After being properly packaged, water and air in the environment cannot penetrate into the battery cell and, therefore, the electrode group 18 and the electrolyte 20 are reasonably separated from the environment. The performances of the electrolyte 20 in the lithium ion battery cannot deteriorate easily. It should be noticed that according to an alternative embodiment of the present invention, the inner bonding layer 12 can be made from other bonding materials having characteristics similar to those of polypropylene or the like.
The intermediate stainless steel layer 14 has desirable strength and density, so as to support and protect the electrode group 18 and the electrolyte 20 received therein, as well as prevent the water or the gas in the circumstances from penetrating into the battery cell.
The outer polyester layer 16 is exposed to the outer environment, which can protect the intermediate layer, such as preventing the stainless steel from being oxidized, being eroded or being scratched. In the illustrated embodiment, the polyester layer 16 is polyethylene terephthalate (PET) layer. However, according to an alternative embodiment of the present invention, the outer protective layer can also be made from other materials having similar performances as those of polyethylene terephthalate or the like.
It should be noticed that, the term “electrode group” 18 in the present invention refers to a structure which may include an anode plate and a cathode plate that are wound with a separator disposed therebetween. It should be understood that various modifications can be made to the structure of the battery cell according to different requirements of actual use. Consequently, the description regarding the electrode group 18 in the specification is only intended to explain the concept of the present invention, which will not in any way limit the scope of the present invention.
The lithium ion battery cell having the battery pack 10, in accordance with the embodiment of the present invention, has desirable strength. There is no need to add an additional protective layer to reduce the total volume of the battery cell and improve the energy density thereof. Additionally, due to the arrangement of the intermediate stainless steel layer 14, even though the inner bonding layer is damaged in packaging or in use, the intermediate stainless steel layer 14 still will not react with lithium or lithium ion of the battery cell.
Referring to
In the package of the battery cell, the electrode group 18 and the electrolyte 20 are suitably received in the receiving portion 24. The edge 28 of the polypropylene layer 12 of the cover 32 and the polypropylene layer 12 of the peripheral packing portion 26 of the receiving portion 22 are in tight contact with each other and bonded together via thermal melting to seal the chamber 26. It should be appreciated that the bonding of the packing portion 26 to the cover 32 are not limited to thermal melting as any other form of bonding or sealing may be used, as known to those skilled in the art.
It should be understood that, the present invention only set forth one specific manner for packaging the battery cell. However, according to other embodiments of the present invention, the shape of the receiving housing can be adjusted in accordance with different shape of the electrode group and configuration of the elements coupled to the battery cell, so as to receive the electrode group and the electrolyte smoothly.
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 one ordinary skilled in the art. Consequently, the present invention is not limited to the specific details and the illustrative examples shown and described.
| Number | Date | Country | Kind |
|---|---|---|---|
| CN 200810218614.1 | Oct 2008 | CN | national |
The present patent invention claims priority to Chinese Patent Application No. CN 200810218614.1 filed Oct. 24, 2008, which is incorporated by reference herein in its entirety.
