Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Cell enclosure structure – e.g. – housing – casing – container,...
Reexamination Certificate
1999-03-10
2001-06-26
Brouillette, Gabrielle (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Cell enclosure structure, e.g., housing, casing, container,...
C429S180000
Reexamination Certificate
active
06251537
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 having an improved seal structure between electrode tabs acting as terminals of the battery and a case, thereby preventing leakage of electrolyte.
2. Description of the Related Art
As portable wireless electronic apparatuses such as a camcorder, cellular phone or laptop computer becomes lighter and requires high functionality, a high performance secondary battery is regarded as a driving power source. Such secondary battery includes nickel-cadmium battery, nickel-hydrogen battery, nickel-zinc battery, lithium secondary battery and the like. In particular, the lithium secondary battery has a long life span and large capacity.
The lithium secondary battery is classified into a Li metal battery and a Li ion battery both using a liquid electrolyte, and a Li polymer battery using a polymer solid electrolyte, according to the type of electrolyte.
The Li polymer battery is classified into a complete solid type Li polymer battery which does not contain an organic liquid electrolyte at all, and a Li ion polymer battery using a gel type polymer electrolyte containing small amounts of organic liquid electrolytes, according to the type of polymer solid electrolyte.
Thus, leakage of the organic liquid electrolyte is serious in the case of the secondary battery containing a organic liquid electrolyte, e.g. Li ion polymer battery, while the complete solid type Li polymer battery has nothing to do with the leakage problem of organic liquid electrolyte.
FIG. 1
is an exploded perspective view showing an example of a conventional secondary battery.
Referring to
FIG. 1
, the secondary battery includes a battery body
14
in which a positive electrode (not shown), a negative electrode (not shown) and a separator(not shown) are stacked, and a dielectric package
15
for sealing around the battery body
14
. The, the battery body
14
and electrode tabs
17
and
17
′ acting as electrical paths for inducing current formed in the battery body
14
to the outside are connected by connection tabs
16
and
16
′ respectively provided on the positive and negative electrodes, and the electrode tabs
17
and
17
′ are installed to be exposed outward by a predetermined length.
The dielectric package
15
is in the form of a dielectric film obtained by forming a heat sealable material layer on a metal base such as aluminum thin film. The dielectric package
15
seals the battery body
14
as follows. That is, while the positive electrode tabs
17
and
17
′ are partially exposed to the outside of the dielectric package
15
, the battery body
14
is put on the dielectric package
15
. Then, the dielectric package
15
is folded in half, and the pressure and heat are applied thereto such that the heat sealable material layers formed along the edges of an upper dielectric package
15
a
and a lower dielectric package
15
b
adhere to each other, thereby sealing the battery body
14
.
FIG. 2
is a section view showing the sealing state between the dielectric package
15
and the electrode tabs
17
and
17
′ of the conventional secondary battery shown in FIG.
1
.
Referring to
FIG. 2
, upper and lower surfaces of the electrode tabs
17
and
17
′ are surrounded by the upper and lower dielectric packages
15
a
and
15
b.
However, spaces
19
through which the leakage of the organic liquid electrolyte can be made are uaually formed at both sides of the electrode tabs
17
and
17
′. Such spaces at both sides of the electrode tabs disrupt complete sealing, the detailed reason of which are as follows.
First, adhesive force between metals forming the electrode tabs
17
and
17
′ and the heat sealable material layer of the dielectric package
15
is weak. Second, the fluidity of the heat sealable material layer of the dielectric package
15
is poor. That is, for complete sealing, the heat sealable material layer of the dielectric package
15
should show good fluidity when melted by the pressure and heat applied for sealing so as to be flowed into the sides of the electrode tabs
17
and
17
′ to fill the spaces. However, due to the poor fluidity of the heat sealable material layer, the spaces formed at the sides of the electrode tabs
17
and
17
′ are not well filled.
Thus, in the conventional secondary battery, the incomplete sealing near the electrode tabs
17
and
17
′, between the upper and lower dielectric packages
15
a
and
15
b,
leaks the organic liquid electrolyte, thereby deteriorating charging and discharging property and reducing the life span of the battery.
SUMMARY OF THE INVENTION
To solve the above problems, it is an object of the present invention to provide a secondary battery in which the sealing state between electrode tabs connected to a battery body, and upper and lower dielectric packages is improved, thereby preventing leakage of an organic liquid electrolyte.
Accordingly, to achieve the above object, there is provided a secondary battery comprising a battery body having a positive electrode, a negative electrode and a separator which are stacked, and electrode tabs for inducing current generated therein to the outside; dielectric package having upper and lower dielectric packages, for enclosing the battery body by sealing edge portions of the upper and lower dielectric packages while the electrode tabs are partially exposed to the outside; and sealing materials coated on predetermined portions of the electrode tabs by a predetermined width, for preventing leakage of an organic liquid electrolyte while being interposed and fused between the edge portions of the upper and lower dielectric packages.
Preferably, in the secondary battery of present invention, the sealing materials each have side arms extended toward both sides by a predetermined length.
Preferably, in the secondary battery of present invention, the dielectric package has a heat sealable material layer coated on the inner surface of the dielectric package.
Preferably, in the secondary battery of present invention, the dielectric package material layer is formed of ionomer.
Preferably, in the secondary battery of present invention, the sealing materials are formed of the same material as the heat sealable material layer coated on the inner surface of the dielectric package, or a material being attachable to the heat sealable material layer coated on the inner surface of the dielectric package by heat under pressure.
Preferably, in the secondary battery of present invention, the sealing materials are selected from the group consisting of ionomer, copolymer of ethylene and acrylic acid, polyethylene resin, polypropylene resin, polyamide resin, polyester resin and polyurethane resin.
Preferably, in the secondary battery of present invention, the ionomer is obtained by adding one of sodium (Na), potassium (K), magnesium (Mg) and zinc (Zn) to a copolymer of ethylene and acrylic acid to neutralize carboxylic acid of its side chain.
Preferably, in the secondary battery of present invention, the separator is solid type separator, gel type separator, or hybrid type separator.
REFERENCES:
patent: 3660168 (1972-05-01), Ralston
patent: 4177330 (1979-12-01), Gordon
patent: 4567121 (1986-01-01), Gilmour
patent: 4659636 (1987-04-01), Suzuki
patent: 4664994 (1987-05-01), Koike
patent: 4929518 (1990-05-01), Yoshinaka
patent: 5472802 (1995-12-01), Holland
patent: 5601946 (1997-02-01), Hattori
patent: 0 081 339 (1983-06-01), None
patent: 0 397 248 (1990-11-01), None
patent: 0 852 404 (1998-07-01), None
patent: 0 862 227 (1998-09-01), None
patent: 0 938 145 (1999-08-01), None
patent: 97/08762 (1997-03-01), None
Patent Abstracts of Japan no. 60-230352, Nov. 15, 1985.
Kim Han-sung
Noh Hyung-gon
Roh Whan-jin
Brouillette Gabrielle
Lowe Hauptman & Gilman & Berner LLP
Ruthkosky Mark
Samsung Display Devices, Ltd.
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