Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Cell enclosure structure – e.g. – housing – casing – container,...
Reexamination Certificate
1999-05-10
2001-05-22
Chaney, Carol (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Cell enclosure structure, e.g., housing, casing, container,...
C429S163000, C429S185000, C429S053000, C429S055000, C429S056000, C429S007000
Reexamination Certificate
active
06235424
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a secondary battery and, more particularly, to a cap assembly for a secondary battery, which can prevent electrolyte from leaking out of the battery while providing safety and reliability of the battery.
2. Description of the Prior Art
Generally, 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 cap assembly of a conventional Li-ion battery.
A cap assembly
6
is insulated from the can
4
by a gasket
8
. That is, the upper end of the can
4
is crimped on the 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 plate
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, as the circuit breaker
18
is welded to the safety plate
14
with the insulator
16
interposed therebetween, the structure of the cap assembly is complicated. In addition, since the circuit breaker
18
and the insulator
16
are supported by the safety plate
14
, the safety plate
14
may become deformed, causing the safety plate
14
and the circuit breaker
18
to malfunction.
Particularly, in the case of a cylindrical Li-ion battery, airtightness depends on a contacting area between the safety plate
14
and the gasket
8
. However, in the conventional battery, an insufficient contacting area is obtained, negatively affecting airtightness.
SUMMARY OF THE INVENTION
Therefore, 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 cap assembly for a secondary battery, in which the assembling structure of a safety plate, an insulator, and a circuit breaker is improved so as to increase safety, reliability, and a seal effect of the battery.
To achieve the above objective, the present invention provides a cap assembly for a battery having a can filled with an electrolyte and an electrode assembly, the cap assembly being close-tightly mounted on the upper end of the can with a gasket interposed between the cap assembly and the upper end.
The cap assembly comprises a safety plate whose edge extended at the right angle with respect to the plane of the safety plate, a cap cover disposed on the safety plate, a circuit breaker disposed under the safety plate, and an insulator disposed between the safety plate and the circuit breaker.
The safety plate is provided with a first flange in which the insulator is tightly fitted, and the insulator is provided with a second flange in which the circuit breaker is tightly inserted.
The cap assembly may further comprises a current control member disposed between the cap cover and the safety plate.
According to a feature of the present invention, the gasket is made of an identical material as the insulator.
According to another feature of the present invention, the first and second flanges are forced inwardly such that the first and second flanges are inclined at a predetermined angle with respect to the longitudinal axis of the battery.
According to another aspect of the present invention, a method for assembling a cap assembly for a battery comprises the steps of preparing flange portions on a safety plate and an insulator, forcedly fitting the insulator and a circuit breaker into the flange portions of the safety plate and the insulator, respectively, mounting the safety plate and the insulator on the upper end of a can with a gasket disposed therebetween, mounting a cap cover on the safety plate, and crimping the upper end of the can on the cap assembly.
REFERENCES:
patent: 5500026 (1996-03-01), Heller et al.
patent: 5876868 (1999-03-01), Tanida et al.
Baker & McKenzie
Chaney Carol
Martin Angela J.
Samsung Display Devices Co. Ltd.
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