TECHNICAL FIELD
[0002] The present invention relates to a secondary battery
having a structure that discharges a gas inside a pouch and
15 blocks an inflow of moisture outside the pouch, and a method
for manufacturing the same.
BACKGROUND ART
[0003] In general, secondary batteries refer to chargeable
and dischargeable batteries, unlike primary batteries that are
20 not chargeable. Such a secondary battery is being widely used
in the high-tech electronic fields such as mobile phones,
notebook computers, and camcorders.
[0004] The secondary batteries are classified into a can type
secondary battery, in which an electrode assembly is embedded
25 in a metal can, and a pouch type secondary battery in which an
2
electrode assembly is embedded in a pouch. Also, the pouch
type secondary battery comprises an electrode assembly, an
electrode lead coupled to an electrode tab of the electrode
assembly, and a pouch accommodating the electrode assembly in
5 a state in which a front end of the electrode lead is drawn
out.
[0005] However, the secondary battery having the above
structure has a problem in that when a gas pressure inside the
pouch increases due to overcharging or short circuit, the pouch
10 is vented to cause explosion or ignition.
DISCLOSURE OF THE INVENTION
TECHNICAL PROBLEM
[0006] The present invention is invented to solve the above
problems, and an object of the present invention is to provide
15 a secondary battery, which comprises a gas discharge part that
discharges only a gas generated in a pouch to the outside,
thereby preventing a pouch from being exploded or ignited while
the pouch is vented, particularly, preventing moisture from
being introduced into the pouch so as to prevent the secondary
20 battery from being deteriorated in performance, and a method
for manufacturing the same.
[0007] In addition, an object of the present invention
provides is to provide a secondary battery comprising a gas
discharge part between an electrode lead and a sealing part,
25 between which possibility of venting is high, thereby improving
3
safety of the secondary battery, and a method for manufacturing
the same.
TECHNICAL SOLUTION
[0008] A secondary battery according to the present invention
5 for achieving the above objects comprises: an electrode
assembly to which an electrode lead is coupled; a pouch
comprising an accommodation part configured to accommodate the
electrode assembly in a state, in which a front end of the
electrode lead is withdrawn to the outside, and a sealing part
10 formed along a circumference of the accommodation part to seal
the accommodation part; and a gas discharge part provided in
the pouch to discharge a gas from the inside to the outside of
the pouch and block an inflow of moisture from the outside to
the inside of the pouch, wherein the gas discharge part
15 comprises: a gas transmitting film having air permeability, by
which the gas inside the accommodation part is discharged to
the outside; and a moisture absorbing material that absorbs
the passing through the gas transmitting film to block the
inflow of the moisture from the outside to the inside of the
20 pouch.
[0009] The gas discharge part may be provided between the
electrode lead and the sealing part.
[0010] The gas discharge part may be provided in the sealing
part.
25 [0011] An adhesive film configured to seal a gap between the
4
gas discharge part and the sealing part may be provided between
the gas discharge part and the sealing part.
[0012] The adhesive film may be made of a material having air
permeability.
5 [0013] The adhesive film may be provided to surround an entire
outer circumferential surface of the gas transmitting film so
as not to expose the gas discharge part to the outside.
[0014] The adhesive film may have air permeability less than
that of the gas transmitting film.
10 [0015] The moisture absorbing material may be provided on an
outer surface of the gas transmitting film.
[0016] The moisture absorbing material may be provided to be
contained in the gas transmitting film.
[0017] The gas transmitting film may be made of a
15 thermoplastic resin, and the moisture absorbing material may
be made of oxide that absorbs moisture.
[0018] A method for manufacturing a secondary battery
according to the present invention comprises: a process (a) of
preparing a pouch provided with an upper case and a lower case,
20 wherein the upper case is provided with an upper accommodation
surface and an upper sealing surface, and the lower case is
provided with a lower accommodation surface and a lower sealing
surface; a process (b) of disposing an electrode assembly, to
which an electrode lead is coupled, in an accommodation part
25 formed by connecting the upper accommodation surface to the
5
lower accommodation surface after the upper case and the lower
case are disposed to correspond to each other; a process (c)
of manufacturing a gas discharge part comprising a gas
transmitting film having air permeability and a moisture
5 absorbing material that absorbs moisture passing through the
gas transmitting film; a process (d) of disposing the gas
discharge part between the upper sealing surface of the upper
case and the lower sealing surface of the lower case; and a
process (e) of thermally fusing the upper sealing surface and
10 the lower sealing surface to form a sealing part.
[0019] In the process (d), the gas discharge part may be
provided between the upper sealing surface and the lower
sealing surface, which correspond to the electrode lead.
[0020] The method may further comprise, after the gas
15 discharge part is manufactured in the process (c), a process
of attaching an adhesive film to the outside of the gas
discharge part.
[0021] In the process(c), the moisture absorbing material may
be provided outside the gas transmitting film.
20 [0022] In the process (c), the moisture absorbing material
may be contained in the gas transmitting film when the gas
transmitting film is manufactured.
ADVANTAGEOUS EFFECTS
[0023] The secondary battery of the present invention may
25 comprise the gas discharge part between the electrode lead and
6
the sealing part of the pouch, and the gas discharge part may
comprise the gas transmitting film and the moisture absorbing
material. That is, the gas discharge part may be provided
between the pouch of the electrode lead and the sealing part,
5 between which the possibility of the venting is high, to
improve the safety of the secondary battery.
[0024] That is to say, the gas discharge part may stably
discharge the gas from the inside of the pouch to the outside
through the gas transmitting film and may absorb the moisture,
10 which passes through the gas transmitting film, through the
moisture absorbing material to block the inflow of the moisture
into the pouch.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is an exploded perspective view of a secondary
15 battery according to a first embodiment of the present
invention.
[0026] FIG. 2 is a plan view of the secondary battery
according to the first embodiment of the present invention.
[0027] FIG. 3 is a cross-sectional view taken along line A-A
20 of FIG. 2.
[0028] FIG. 4 is a cross-sectional view taken along line B-B
of FIG. 3.
[0029] FIG. 5 is a cross-sectional view illustrating a second
example of a moisture absorbing material of the secondary
25 battery according to the first embodiment of the present
7
invention.
[0030] FIG. 6 is a cross-sectional view illustrating a third
example of the moisture absorbing material of the secondary
battery according to the first embodiment of the present
5 invention.
[0031] FIG. 7 is a flowchart illustrating a method for
manufacturing the second battery according to the first
embodiment of the present invention.
[0032] FIGS. 8 to 12 are views illustrating the method for
10 manufacturing the secondary battery according to the first
embodiment of the present invention, wherein FIG. 8 is a
perspective view illustrating a process of preparing a pouch,
FIG. 9 is a perspective view illustrating a process of
disposing an electrode assembly, FIG. 10 is a view illustrating
15 a process of manufacturing a gas discharge part, FIG. 11 is a
perspective illustrating a process of disposing the gas
discharge part, and FIG. 12 is a perspective view illustrating
a process of manufacturing a secondary battery to which the
gas discharge part is coupled.

CLAIMS
1. A secondary battery comprising:
an electrode assembly to which an electrode lead is
5 coupled;
a pouch comprising an accommodation part configured to
accommodate the electrode assembly in a state, in which a front
end of the electrode lead is withdrawn to the outside, and a
sealing part formed along a circumference of the accommodation
10 part to seal the accommodation part; and
a gas discharge part provided in the pouch to discharge
a gas from the inside to the outside of the pouch and block an
inflow of moisture from the outside to the inside of the pouch,
wherein the gas discharge part comprises: a gas
15 transmitting film having air permeability, by which the gas
inside the accommodation part is discharged to the outside;
and a moisture absorbing material that absorbs the passing
through the gas transmitting film to block the inflow of the
moisture from the outside to the inside of the pouch.
20
2. The secondary battery of claim 1, wherein the gas
discharge part is provided between the electrode lead and the
sealing part.
25 3. The secondary battery of claim 1, wherein the gas
28
discharge part is provided in the sealing part.
4. The secondary battery of claim 2 or 3, wherein an
adhesive film configured to seal a gap between the gas
5 discharge part and the sealing part is provided between the
gas discharge part and the sealing part.
5. The secondary battery of claim 4, wherein the
adhesive film is made of a material having air permeability.
10
6. The secondary battery of claim 5, wherein the
adhesive film is provided to surround an entire outer
circumferential surface of the gas transmitting film so as not
to expose the gas discharge part to the outside.
15
7. The secondary battery of claim 5, wherein the
adhesive film has air permeability less than that of the gas
transmitting film.
20 8. The secondary battery of claim 1, wherein the
moisture absorbing material is provided on an outer surface of
the gas transmitting film.
9. The secondary battery of claim 1, wherein the
25 moisture absorbing material is provided to be contained in the
29
gas transmitting film.
10. The secondary battery of claim 1, wherein the gas
transmitting film is made of a thermoplastic resin, and
5 the moisture absorbing material is made of oxide that
absorbs moisture.
11. A method for manufacturing a secondary battery, the
method comprising:
10 a process (a) of preparing a pouch provided with an upper
case and a lower case, wherein the upper case is provided with
an upper accommodation surface and an upper sealing surface,
and the lower case is provided with a lower accommodation
surface and a lower sealing surface;
15 a process (b) of disposing an electrode assembly, to
which an electrode lead is coupled, in an accommodation part
formed by connecting the upper accommodation surface to the
lower accommodation surface after the upper case and the lower
case are disposed to correspond to each other;
20 a process (c) of manufacturing a gas discharge part
comprising a gas transmitting film having air permeability and
a moisture absorbing material that absorbs moisture passing
through the gas transmitting film;
a process (d) of disposing the gas discharge part between
25 the upper sealing surface of the upper case and the lower
30
sealing surface of the lower case; and
a process (e) of thermally fusing the upper sealing
surface and the lower sealing surface to form a sealing part.
5 12. The method of claim 11, wherein, in the process (d),
the gas discharge part is provided between the upper sealing
surface and the lower sealing surface, which correspond to the
electrode lead.
10 13. The method of claim 11, further comprising, after
the gas discharge part is manufactured in the process (c), a
process of attaching an adhesive film to the outside of the
gas discharge part.
15 14. The method of claim 11, wherein, in the process(c),
the moisture absorbing material is provided outside the gas
transmitting film.
15. The method of claim 11, wherein, in the process (c),
20 the moisture absorbing material is contained in the gas
transmitting film when the gas transmitting film is
manufactured.