【Technical Field】
[1] This application claims the benefit of priority
to Korean Patent Application No. 2020-0085641 filed on
July 10, 2020, the disclosure of which is incorporated
herein by reference in its entirety.
[2] This application claims the benefit of priority
to Korean Patent Application No. 2021-0078634 filed on
June 17, 2021, the disclosure of which is incorporated
herein by reference in its entirety.
[3] The present invention relates to a secondary
battery including a gas discharge filter and a secondary
battery manufacturing method, and more particularly to a
secondary battery including a case having a gas discharge
portion configured to selectively discharge gas in the
secondary battery while interrupting introduction of
moisture into the secondary battery and a secondary
battery manufacturing method.
【Background Art】
2
[4] With recent diversification of devices that use
batteries, demand for high-capacity and high-density
batteries has increased. In particular, concern about a
pouch-shaped secondary battery configured such that the
thickness of an aluminum laminate sheet is reduced to
obtain a high-capacity and high-density battery has
increased.
[5] The pouch-shaped secondary battery is generally
formed by shaping an aluminum laminate sheet to form a
receiving portion and receiving an electrode assembly
including a positive electrode, a separator, and a
negative electrode in the receiving portion. The
aluminum laminate sheet is easily deformed and thus
manufactured in various forms, whereby it is possible to
form pouch-shaped secondary batteries suitable for
various electronic devices. In addition, since the
aluminum laminate sheet is light, unlike a conventional
cylindrical secondary battery or a prismatic secondary
battery, it is possible to increase energy density per
weight of the pouch-shaped secondary battery.
[6] FIG. 1 is a perspective view of a conventional
pouch-shaped secondary battery.
[7] The conventional pouch-shaped secondary battery
includes an electrode assembly 10 having electrode leads
11 protruding therefrom and a case 20 having a receiving
3
portion 21 configured to receive the electrode assembly.
In the pouch-shaped secondary battery, the electrode
assembly 10 is received in the receiving portion 21, and
the periphery of the receiving portion 21 is hermetically
sealed to form a sealed portion 22. The sealed portion
22 is formed to prevent materials present in the pouchshaped
secondary battery from reacting with external air.
However, a separate member capable of removing gas
generated in the receiving portion is not provided. In
the pouch-shaped secondary battery having the above
structure, it is difficult to efficiently remove gas
generated at the time of charging and discharging the
secondary battery. In particular, when heat is
generated due to overcharging or malfunction of the
secondary battery, the case may rupture or explode,
whereby noxious gases or chemicals may be discharged
from the secondary battery.
[8] In order to improve safety of the pouch-shaped
case, the conventional pouch-shaped secondary battery
has a material capable of removing gas contained therein
or has a separate gas receiving portion in addition to
the receiving portion. In the case in which the gas
removal material is contained in the pouch-shaped
secondary battery, however, the gas removal material
disturbs operation of the pouch-shaped secondary battery,
4
whereby efficiency of the battery is reduced. In the
case in which the gas receiving portion is provided, the
capacity of the battery based on the volume thereof is
reduced, since the gas receiving portion has no relation
to operation of the battery.
[9] In order to solve this, Patent Document 1
discloses that a hydrogen permeation member is formed on
at least a part of a metal tab lead exposed outwards from
a sheathing member and the hydrogen permeation member
extends from the inside to the outside of the sheathing
member. In Patent Document 1, however, it is not
possible to prevent permeation of moisture into a battery
as the result of use of the hydrogen permeation member,
whereby operation of the battery is disturbed and gases
other than hydrogen are not efficiently discharged.
[10] In Patent Document 2, an electrode lead is formed
so as to have a porous structure, and a gas adsorption
material is formed on the inner surfaces of pores of the
electrode lead by coating. However, the gas adsorption
material acts as resistance, whereby overall efficiency
of the battery may be reduced.
[11] Therefore, there is a need for a construction
capable of improving safety of a battery while not
reducing performance and efficiency of the battery.
[12] (Prior Art Documents)
5
[13] (Patent Document 1) Japanese Patent Application
Publication No. 2014-212034
[14] (Patent Document 2) Korean Patent Application
Publication No. 2017-0082239
【Disclosure】
【Technical Problem】
[15] The present invention has been made in view of
the above problems, and it is an object of the present
invention to provide a pouch-shaped secondary battery
having a gas discharge portion provided in a sealed
portion thereof, the gas discharge portion being
configured to selectively discharge only gas, whereby
gas is efficiently discharged while no moisture
permeates from the outside, and therefore safety of the
battery is improved while performance of the battery is
maintained.
[16] It is another object of the present invention to
provide a secondary battery manufacturing method capable
of hermetically sealing the gas discharge portion, a
case, and an electrode lead together, whereby it is
possible to manufacture a secondary battery configured
such that the case is hermetically sealed very well, and
therefore a battery defect rate is low while gas
discharge is easily achieved.
6
【Technical Solution】
[17] In order to accomplish the above objects, a
secondary battery according to the present invention
includes a pouch-shaped case having a receiving portion
configured to receive an electrode assembly, a sealed
portion formed as the result of hermetically sealing the
periphery of the receiving portion, and a gas discharge
portion disposed in the sealed portion, the gas discharge
portion having one end disposed in contact with the
receiving portion and the other end disposed in contact
with the outside, the gas discharge portion configured to
selectively discharge only gas.
[18] The gas discharge portion may be made of a gas
discharge material having a higher gas permeability than
a moisture permeability.
[19] The gas discharge material may have an annual
moisture permeability of 50 ppm or less.
[20] The gas discharge material may be polypropylene
(PP), polytetrafluoroethylene (PTFE), polyethylene (PE),
polyethylene tetraphthalate (PET), or a mixture thereof.
[21] The gas discharge portion may have a thickness
of 100 μm to 600 μm.
[22] The gas discharge portion may wrap an electrode
lead protruding outwards from the electrode assembly.
7
[23] The pouch-shaped case may include a laminate
sheet, and contact portions of the gas discharge portion
and the laminate sheet may be coated with polypropylene.
[24] The secondary battery according to the present
invention includes the pouch-shaped case and an electrode
assembly. The present invention provides a secondary
battery manufacturing method including (S1) applying a
gas discharge material having a higher gas permeability
than a moisture permeability to at least a part of the
surface of an electrode lead of an electrode assembly;
and (S2) receiving the electrode assembly in a receiving
portion formed in a pouch-shaped case having a gas
discharge portion and then hermetically sealing the case.
[25] In the secondary battery manufacturing method
according to the present invention, the gas discharge
material may include polypropylene (PP),
polytetrafluoroethylene (PTFE), polyethylene (PE),
polyethylene tetraphthalate (PET), or a mixture thereof.
[26] In the secondary battery manufacturing method
according to the present invention, in step S2, the gas
discharge material and the pouch-shaped case may be
coupled to each other by thermal fusion performed at
least once to ten times.
[27] In the secondary battery manufacturing method
according to the present invention, the gas discharge
8
portion may undergo a surface reforming process.
[28] In the secondary battery manufacturing method
according to the present invention, the gas discharge
portion may have a thickness of 100 μm to 600 μm.
[29] In the present invention, one or more
constructions that do not conflict with each other may
be selected and combined from among the above
constructions.
【Advantageous Effects】
[30] A secondary battery according to the present
invention includes a gas discharge portion capable of
selectively discharging only gas, whereby gas is
efficiently discharged from the secondary battery, and
therefore safety of the secondary battery is improved
while performance of the secondary battery is maintained.

【Claim 1】 A pouch-shaped case comprising:
a receiving portion configured to receive an
electrode assembly;
a sealed portion formed as a result of hermetically
sealing a periphery of the receiving portion; and
a gas discharge portion disposed in the sealed
portion, the gas discharge portion having one end
disposed in contact with the receiving portion and the
other end disposed in contact with an outside, the gas
discharge portion configured to selectively discharge
only gas.
【Claim 2】 The pouch-shaped case according to claim 1,
wherein the gas discharge portion is made of a gas
discharge material having a higher gas permeability than
a moisture permeability.
【Claim 3】 The pouch-shaped case according to claim 2,
wherein the gas discharge material has an annual
moisture permeability of 50 ppm or less.
【Claim 4】 The pouch-shaped case according to claim 3,
wherein the gas discharge material comprises
28
polypropylene (PP), polytetrafluoroethylene (PTFE),
polyethylene (PE), polyethylene tetraphthalate (PET), or
a mixture thereof.
【Claim 5】 The pouch-shaped case according to claim 1,
wherein the gas discharge portion has a thickness of 100
μm to 600 μm.
【Claim 6】 The pouch-shaped case according to claim 1,
wherein the gas discharge portion wraps an electrode
lead protruding outwards from the electrode assembly.
【Claim 7】 The pouch-shaped case according to claim 1,
wherein
the pouch-shaped case comprises a laminate sheet,
and
contact portions of the gas discharge portion and
the laminate sheet are coated with polypropylene.
【Claim 8】 A secondary battery comprising:
the pouch-shaped case according to any one of claims
1 to 7; and
an electrode assembly.
【Claim 9】 A secondary battery manufacturing method
29
comprising:
(S1) applying a gas discharge material having a
higher gas permeability than a moisture permeability to
at least a part of a surface of an electrode lead of an
electrode assembly; and
(S2) receiving the electrode assembly in a
receiving portion formed in a pouch-shaped case having a
gas discharge portion and then hermetically sealing the
case.
【Claim 10】 The secondary battery manufacturing method
according to claim 9, wherein the gas discharge material
comprises polypropylene (PP), polytetrafluoroethylene
(PTFE), polyethylene (PE), polyethylene tetraphthalate
(PET), or a mixture thereof.
【Claim 11】 The secondary battery manufacturing method
according to claim 9, wherein, in step S2, the gas
discharge material and the pouch-shaped case are coupled
to each other by thermal fusion performed at least once
to ten times.
【Claim 12】 The secondary battery manufacturing method
according to claim 9, wherein the gas discharge portion
undergoes a surface reforming process.
30
【Claim 13】 The secondary battery manufacturing method
according to claim 9, wherein the gas discharge portion
has a thickness of 100 μm to 600 μm.