Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Cell enclosure structure – e.g. – housing – casing – container,...
Reexamination Certificate
1999-02-22
2001-07-03
Maples, John S. (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Cell enclosure structure, e.g., housing, casing, container,...
C429S061000, C429S175000, C429S185000
Reexamination Certificate
active
06255016
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a secondary battery and, more particularly, to a secondary battery that is structured to improve a seal effect between a cap assembly and a can to prevent electrolyte from leaking out of the battery while providing safety and reliability to the battery.
2. Description of the Prior Art
Generally, secondary batteries are compact in size and rechargeable, while providing a large capacity. Well known as secondary batteries are a Nickel metal hydride battery, a Lithium(Li) battery, and a Li-ion battery.
Particularly, the Li-ion battery uses lithium metal oxide as a positive active material and carbon or a carbon compound as a negative active material. Lithium salt dissolved in an organic solvent is used as the electrolyte via which the lithium ions move between positive and negative electrodes. Charging and discharging operations are realized while the lithium ions are moved between positive and negative electrodes.
FIG. 4
shows a conventional Li-ion battery.
A roll electrode assembly
2
is inserted into a can
4
filled with electrolyte, the roll electrode assembly
2
consisting of positive and negative electrodes and a separator disposed between the positive and negative electrodes. Mounted on an upper end of the can
4
is a cap assembly
6
.
The cap assembly
6
is insulated from the can
4
by an intermediate gasket
8
. That is, the upper end of the can
4
is crimped on an outer periphery of the cap assembly
6
with the gasket
8
interposed therebetween.
The cap assembly
6
comprises a safety plate
14
provided with a safety groove, a current control member
12
disposed on the safety plate
14
, and a cap cover
10
disposed on the current control member
12
. Attached under the safety valve
14
is a circuit breaker
18
with an insulator
16
disposed therebetween. The circuit breaker
18
is welded on a positive tab
20
so that it is coupled to a positive electrode of the electrode assembly
2
.
In the conventional Li-ion battery structured as in the above, to enhance a seal effect between the cap assembly
6
and the can
4
, tar
22
is deposited between the gasket
8
and the cap assembly
6
. However, because of a chemical reaction between the electrolyte and the tar
22
, the tar
22
may melt, deteriorating the seal effect.
SUMMARY OF THE INVENTION
The present invention has been made in an effort to solve the above described problems.
It is an objective of the present invention to provide a secondary battery that is structured to improve a seal effect between a cap assembly and a can to prevent electrolyte from leaking out of the battery while providing safety and reliability to the battery.
To achieve the above objective, the present invention provides a battery which comprises a can filled with an electrode assembly and an electrolyte, a cap assembly mounted on an upper end of the can, a gasket disposed between the can and the cap assembly to prevent the electrolyte from leaking, and a seal reinforcing member disposed between the gasket and the cap assembly.
The seal reinforcing member is made of a material which forms a tight seal with a material forming the gasket. Preferably, the seal reinforcing member comprises a polymer coated around an outer circumference of the cap assembly.
The cap assembly comprises a cap cover, a current control member disposed under the cap cover, and a plate provided with a safety groove and disposed under the current control member, and the seal reinforcing member is formed around at least one outer circumference of the cap cover, the current control member and the plate.
Preferably, the seal reinforcing member is made of a polymer material selected from the group consisting of fluoride, polyimide, polytetrafluoroethylene, polyethylene, and polypropylene.
More preferably, the seal reinforcing member extends to an edge of the upper surface of the cap cover and to an edge of the lower surface of the current control member.
The battery may further comprises a current breaker disposed under the plate with an insulator in between. The current breaker is attached to a center of the plate.
REFERENCES:
patent: 4401733 (1983-08-01), Shirai et al.
patent: 4521500 (1985-06-01), Watanabe
patent: 5306582 (1994-04-01), Tanaka
patent: 022527 (1979-02-01), None
patent: 017855 (1985-01-01), None
Baker & McKenzie
Maples John S.
Samsung Display Devices Co. Ltd.
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