TECHNICAL FIELD
[0001] This application claims priority from Korean Patent
Application No. 10-2020-0069917, filed on June 9, 2020, the
disclosure of which is incorporated by reference herein.
10
[0002] The present invention relates to a pouch film laminate,
a pouch type battery case, and a pouch type secondary battery,
and more particularly, to a pouch film laminate in which
formability is improved by improving tensile strength and
15 elongation, a pouch type battery case, and a pouch type
secondary battery.
BACKGROUND ART
[0003] In general, types of secondary batteries include a
nickel cadmium battery, a nickel hydride battery, a lithium
20 ion battery, and a lithium ion polymer battery. These
secondary batteries are not only applied and used in small
products such as digital cameras, P-DVDs, MP3Ps, mobile phones,
PDAs, portable game devices, power tools, and E-bikes, but are
also applied and used in large products requiring high output,
25 such as electric vehicles and hybrid vehicles, and a power
2
storage device and a power storage device for backup which
store surplus generated power or renewable energy.
[0004] In order to prepare such a secondary battery, first,
a positive electrode collector and a negative electrode
5 collector are respectively coated with electrode active
material slurries to prepare a positive electrode and a
negative electrode, and the positive electrode and the negative
electrode are then stacked on both sides of a separator to
form an electrode assembly having a predetermined shape. Then,
10 after the electrode assembly is accommodated in a battery case
and an electrolyte solution is injected, the battery case is
sealed.
[0005] The secondary battery is classified into a pouch type,
a can type, and the like, according to a material of a case
15 for accommodating the electrode assembly. The pouch type
accommodates the electrode assembly in a pouch formed of a
flexible polymer material. In addition, the can type
accommodates the electrode assembly in a case formed of a
material such as metal or plastic.
20 [0006] The pouch, which is a case of the pouch type secondary
battery, is prepared by press working of a flexible pouch film
laminate to form a cup portion. Then, when the cup portion is
formed, the electrode assembly is accommodated in an
accommodating space of the cup portion and a sealing portion
25 is sealed to prepare a secondary battery.
3
[0007] Drawing in the press working is performed by inserting
the pouch film laminate into press equipment and applying a
pressure to the pouch film laminate with a punch to stretch
the pouch film laminate. The pouch film laminate is generally
5 composed of a plurality of layers in which a polymer film,
such as polyethylene terephthalate, is laminated on one surface
of a metal gas barrier layer and a sealant layer is laminated
on the other surface thereof, and an about 40 μm thick aluminum
alloy thin film is mainly used as the gas barrier layer.
10 However, such a conventional pouch film laminate had a
limitation in forming a deeper cup portion due to low
formability, and also had a limitation in reducing a radius of
filleting when edges of a bottom portion and edges of an open
portion of the cup portion are filleted. Furthermore, the
15 conventional pouch film laminate had a limitation in forming
an outer wall of the cup portion close to vertical.
Accordingly, there was a problem in that a dead space of the
secondary battery was increased and a size of the electrode
assembly was decreased to reduce energy efficiency to volume.
20 DISCLOSURE OF THE INVENTION
TECHNICAL PROBLEM
[0008] An aspect of the present invention provides a pouch
film laminate, in which formability is excellent by improving
tensile strength and elongation, a pouch type battery case,
25 and a pouch type secondary battery.
4
[0009] The object of the present invention is not limited to
the aforesaid, but other objects not described herein will be
clearly understood by those skilled in the art from
descriptions below.
5 TECHNICAL SOLUTION
[0010] According to an aspect of the present invention, there
is provided a pouch film laminate including: a sealant layer
formed of a first polymer as an innermost layer; a surface
protection layer formed of a second polymer as an outermost
10 layer; an aluminum alloy thin film having a grain size of 10
μm to 13 μm, and a gas barrier layer laminated between the
surface protection layer and the sealant layer, wherein the
gas barrier layer has a thickness of 50 μm to 70 μm, and the
sealant layer has a thickness of 70 μm to 100 μm.
15 [0011] Also, the aluminum alloy thin film may be an aluminum
alloy thin film with alloy number AA8021.
[0012] Furthermore, the aluminum alloy thin film may include
iron in an amount of 1.3 wt% to 1.7 wt%.
[0013] Also, the aluminum alloy thin film may include silicon
20 in an amount of 0.2 wt% or less.
[0014] Furthermore, the gas barrier layer may have a thickness
of 55 μm to 65 μm.
[0015] Also, the sealant layer may have a thickness of 75 μm
to 85 μm.
25 [0016] Furthermore, the first polymer may include
5
polypropylene (PP).
[0017] Also, the surface protection layer may have a thickness
of 5 μm to 25 μm.
[0018] Furthermore, the surface protection layer may have a
5 thickness of 7 μm to 12 μm.
[0019] Also, the second polymer may include polyethylene
terephthalate (PET).
[0020] Furthermore, the pouch film laminate may further
include a drawing assistance layer which is formed of a third
10 polymer and is laminated between the surface protection layer
and the gas barrier layer.
[0021] Also, the drawing assistance layer may have a thickness
of 20 μm to 50 μm.
[0022] Furthermore, the drawing assistance layer may have a
15 thickness of 25 μm to 38 μm.
[0023] Also, a thickness ratio of the drawing assistance layer
to the gas barrier layer may be in a range of 1:1.5 to 1:2.5.
[0024] Furthermore, the third polymer may include Nylon.
[0025] Also, the pouch film laminate may have a total
20 thickness of 160 μm to 200 μm, preferably 170 μm to 200 μm,
and more preferably 180 μm to 200 μm. Furthermore, the pouch
film laminate may have a tensile strength, which is measured
while the pouch film laminate is pulled at a tensile speed of
50 mm/min after being cut to a size of 15 mm × 80 mm, of 200
25 N/15mm to 300 N/15mm, and may have an elongation of 120% to
6
150%.
[0026] According to another aspect of the present invention,
there is provided a pouch type battery case accommodating an
electrode assembly and being prepared by forming a pouch film
5 laminate, wherein the pouch film laminate includes a sealant
layer formed of a first polymer as an innermost layer; a
surface protection layer formed of a second polymer as an
outermost layer; an aluminum alloy thin film having a grain
size of 10 μm to 13 μm, and a gas barrier layer laminated
10 between the surface protection layer and the sealant layer,
wherein the gas barrier layer has a thickness of 50 μm to 70
μm, and the sealant layer has a thickness of 70 μm to 100 μm.
[0027] According to another aspect of the present invention,
there is provided a pouch type secondary battery including an
15 electrode assembly which is formed by stacking a positive
electrode, a separator, and a negative electrode; and a pouch
type battery case accommodating the electrode assembly,
wherein the battery case is prepared by forming a pouch film
laminate, wherein the pouch film laminate includes a sealant
20 layer formed of a first polymer as an innermost layer; a
surface protection layer formed of a second polymer as an
outermost layer; an aluminum alloy thin film having a grain
size of 10 μm to 13 μm, and a gas barrier layer laminated
between the surface protection layer and the sealant layer,
25 wherein the gas barrier layer has a thickness of 50 μm to 70
7
μm, and the sealant layer has a thickness of 70 μm to 100 μm.
[0028] Other specific details of the present invention are
included in the detailed description and drawings.
ADVANTAGEOUS EFFECTS
5 [0029] According to the embodiments of the present invention,
at least the following effects may be achieved.
[0030] Since a gas barrier layer and a sealant layer satisfy
a specific thickness and an aluminum alloy thin film having a
specific grain size is used as a gas barrier layer, a pouch
10 film laminate according to the present invention has excellent
tensile strength, elongation, and toughness. Accordingly, if
the pouch film laminate of the present invention is used, since
a forming depth may be increased without occurrence of pinholes
or cracks during forming of a cup portion, particularly, two
15 cup portions and a radius of curvature of an edge of the cup
portion may be reduced, an accommodating space volume of a
battery assembly may be increased. The effects according to
the present invention are not limited to the contents as
exemplified above, but more various effects are included in
20 the specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is an assembly view of a secondary battery
according to an embodiment of the present invention;
[0032] FIG. 2 is a cross-sectional view of a pouch film
25 laminate according to an embodiment of the present invention;
8
[0033] FIG. 3 is a graph illustrating iron and silicon
contents of an aluminum alloy with alloy number AA8079 and an
aluminum alloy with alloy number AA8021;
[0034] FIG. 4 is a graph illustrating changes in tensile
5 strength, elongation, and grain size according to the iron
content of the aluminum alloy with alloy number AA8079 and the
aluminum alloy with alloy number AA8021; and
[0035] FIG. 5 is magnified scanning electron microscope (SEM)
images of grains of the aluminum alloy with alloy number AA8021
10 and the aluminum alloy with alloy number AA8079.
MODE FOR CARRYING OUT THE INVENTION
[0036] Advantages and features of the present invention, and
implementation methods thereof will be clarified through
following embodiments described with reference to the
15 accompanying drawings. The present invention may, however, be
embodied in different forms and should not be construed as
limited to the embodiments set forth herein. Rather, these
embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
20 present invention to those skilled in the art. Further, the
present invention is only defined by scopes of claims. Like
reference numerals refer to like elements throughout.
[0037] Unless defined otherwise, all terms (including
technical and scientific terms) used herein may be intended to
25 have meanings understood by those skilled in the art. In
9
addition, terms defined in general dictionaries should not be
interpreted abnormally or exaggeratedly, unless clearly
specifically defined.
[0038] The terminology used herein is for the purpose of
5 describing particular example embodiments only and is not
intended to be limiting of the present invention. In the
specification, the terms of a singular form may include plural
forms unless referred to the contrary. It will be further
understood that the terms "comprises" and/or "comprising" when
10 used in this specification, specify the presence of stated
components, but do not preclude the presence or addition of
one or more other components.
[0039] Hereinafter, preferred embodiments of the present
invention will be described in detail with reference to the
15 accompanying drawings.
[0040] FIG. 1 is an assembly view of a secondary battery 1
according to an embodiment of the present invention.
[0041] According to an embodiment of the present invention,
since toughness is increased by improving tensile strength and
20 elongation of a pouch film laminate 135, formability may be
improved when the pouch film laminate 135 is formed to prepare
a pouch type battery case 13.
[0042] The pouch film laminate 135 according to an embodiment
of the present invention includes a sealant layer 1351 formed
25 of a first polymer as an innermost layer; a surface protection
10
layer 1353 formed of a second polymer as an outermost layer;
an aluminum alloy thin film having a grain size of 10 μm to 13
μm, and a gas barrier layer 1352 laminated between the surface
protection layer 1353 and the sealant layer 1351. In this
5 case, the gas barrier layer 1352 has a thickness of 50 μm to
70 μm, and the sealant layer 1351 has a thickness of 70 μm to
100 μm. Particularly, it is desirable that the gas barrier
layer 1352 has a thickness of 55 μm to 65 μm, and the sealant
layer 1351 has a thickness of 75 μm to 85 μm.
10 [0043] The pouch type battery case 13 according to an
embodiment of the present invention accommodating an electrode
assembly 10 and being prepared by forming the pouch film
laminate 135, wherein the pouch film laminate 135 includes the
sealant layer 1351 formed of a first polymer as an innermost
15 layer; the surface protection layer 1353 formed of a second
polymer as an outermost layer; an aluminum alloy thin film
having a grain size of 10 μm to 13 μm, and the gas barrier
layer 1352 laminated between the surface protection layer 1353
and the sealant layer 1351, wherein the gas barrier layer 1352
20 has a thickness of 50 μm to 70 μm, and the sealant layer has
a thickness of 70 μm to 100 μm. Particularly, it is desirable
that the gas barrier layer 1352 has a thickness of 55 μm to 65
μm, and the sealant layer has a thickness of 75 μm to 85 μm.
[0044] The secondary battery 1 according to the embodiment of
25 the present invention includes the electrode assembly 10 which
11
is formed by stacking a positive electrode, a separator, and
a negative electrode; and the pouch type battery case 13
accommodating the electrode assembly 10, wherein the battery
case 13 is prepared by forming the pouch film laminate 135,
5 and the pouch film laminate 135 includes the sealant layer
1351 formed of a first polymer as an innermost layer; the
surface protection layer 1353 formed of a second polymer as an
outermost layer; an aluminum alloy thin film having a grain
size of 10 μm to 13 μm, and the gas barrier layer 1352 laminated
10 between the surface protection layer 1353 and the sealant layer
1351, wherein the gas barrier layer 1352 has a thickness of 50
μm to 70 μm, and the sealant layer 1351 has a thickness of 70
μm to 100 μm. Particularly, it is desirable that the gas
barrier layer 1352 has a thickness of 55 μm to 65 μm, and the
15 sealant layer 1351 has a thickness of 75 μm to 85 μm.
[0045] The electrode assembly 10 is formed by alternatingly
stacking an electrode and a separator. First, a slurry, in
which an electrode active material, a binder, and/or a
conductive agent are mixed, is applied to a positive electrode
20 collector and a negative electrode collector to prepare a
positive electrode and a negative electrode, and, after the
electrode assembly 10 having a predetermined shape is formed
by stacking the positive electrode and the negative electrode
on both sides of the separator, the electrode assembly 10 is
25 inserted into the battery case 13, and the battery case 13 is
12
sealed after injecting an electrolyte.
[0046] Specifically, the electrode assembly 10 includes two
types of electrodes, such as the positive electrode and the
negative electrode, and the separator disposed between the
5 electrodes to insulate the electrodes from each other. The
electrode assembly 10 includes a stacked type, a jelly-rolltype, and a stack and folding type. The two types of
electrodes, that is, the positive electrode and the negative
electrode, have a structure in which active material slurries
10 are applied to electrode collectors in the form of a metal
foil or metal mesh including aluminum and copper, respectively.
The slurry may be typically formed by stirring a granular
active material, an auxiliary conductor, a binder, and a
conductive agent in a state in which a solvent is added. The
15 solvent is removed in a subsequent process.

CLAIMS
1. A pouch film laminate comprising:
a sealant layer formed of a first polymer as an innermost
5 layer;
a surface protection layer formed of a second polymer as
an outermost layer;
an aluminum alloy thin film having a grain size of 10 μm
to 13 μm, and
10 a gas barrier layer laminated between the surface
protection layer and the sealant layer,
wherein the gas barrier layer has a thickness of 50 μm
to 70 μm, and
the sealant layer has a thickness of 70 μm to 100 μm.
15
2. The pouch film laminate of claim 1, wherein the aluminum
alloy thin film has alloy number AA8021.
3. The pouch film laminate of claim 1, wherein the aluminum
20 alloy thin film comprises iron in an amount of 1.3 wt% to 1.7
wt%.
4. The pouch film laminate of claim 1, wherein the aluminum
alloy thin film comprises silicon in an amount of 0.2 wt% or
25 less.
43
5. The pouch film laminate of claim 1, wherein the gas
barrier layer has a thickness of 55 μm to 65 μm.
5 6. The pouch film laminate of claim 1, wherein the sealant
layer has a thickness of 75 μm to 85 μm.
7. The pouch film laminate of claim 1, wherein the first
polymer comprises polypropylene (PP).
10
8. The pouch film laminate of claim 1, wherein the surface
protection layer has a thickness of 5 μm to 25 μm.
9. The pouch film laminate of claim 1, wherein the surface
15 protection layer has a thickness of 7 μm to 12 μm.
10. The pouch film laminate of claim 1, wherein the second
polymer comprises polyethylene terephthalate (PET).
20 11. The pouch film laminate of claim 1, further comprising a
drawing assistance layer formed of a third polymer and
laminated between the surface protection layer and the gas
barrier layer.
25 12. The pouch film laminate of claim 11, wherein the drawing
44
assistance layer has a thickness of 20 μm to 50 μm.
13. The pouch film laminate of claim 11, wherein the drawing
assistance layer has a thickness of 25 μm to 38 μm.
5
14. The pouch film laminate of claim 11, wherein a thickness
ratio of the drawing assistance layer to the gas barrier layer
is in a range of 1:1.5 to 1:2.5.
10 15. The pouch film laminate of claim 12, wherein the third
polymer comprises Nylon.
16. The pouch film laminate of claim 1, wherein the pouch
film laminate has a total thickness of 160 μm to 200 μm.
15
17. The pouch film laminate of claim 1, wherein the pouch
film laminate has a tensile strength, which is measured while
the pouch film laminate is pulled at a tensile speed of 50
mm/min after being cut to a size of 15 mm × 80 mm, of 200
20 N/15mm to 300 N/15mm, and has an elongation of 120% to 150%.
18. A pouch type battery case accommodating an electrode
assembly and being prepared by forming a pouch film laminate,
wherein the pouch film laminate comprises:
25 a sealant layer formed of a first polymer as an innermost
45
layer;
a surface protection layer formed of a second polymer as
an outermost layer;
an aluminum alloy thin film having a grain size of 10 μm
5 to 13 μm, and
a gas barrier layer laminated between the surface
protection layer and the sealant layer,
wherein the gas barrier layer has a thickness of 50 μm
to 70 μm, and
10 the sealant layer has a thickness of 70 μm to 100 μm.
19. A pouch type secondary battery comprising an electrode
assembly which is formed by stacking a positive electrode, a
separator, and a negative electrode; and
15 a pouch type battery case accommodating the electrode
assembly,
wherein the battery case is prepared by forming a pouch
film laminate,
wherein the pouch film laminate comprises:
20 a sealant layer formed of a first polymer as an innermost
layer;
a surface protection layer formed of a second polymer as
an outermost layer;
an aluminum alloy thin film having a grain size of 10 μm
25 to 13 μm, and
46
a gas barrier layer laminated between the surface
protection layer and the sealant layer,
wherein the gas barrier layer has a thickness of 50 μm
to 70 μm, and
5 the sealant layer has a thickness of 70 μm to 100 μm.