【Technical Field】
[1] This application claims the benefit of priority
to Korean Patent Application No. 2020-0124896 filed on
September 25, 2020, the disclosure of which is
incorporated herein by reference in its entirety.
[2] The present invention relates to a pouch-shaped
battery case shaping apparatus including a volatile
lubricant supply unit and a pouch-shaped battery case
manufacturing method using the same. More particularly,
the present invention relates to a pouch-shaped battery
case shaping apparatus including a punch configured to
shape a laminate sheet used as a pouch-shaped battery
case into a cuboid, wherein the pouch-shaped battery case
shaping apparatus further includes a volatile lubricant
supply unit configured to supply a volatile lubricant
used to minimize surface damage to the laminate sheet
between the laminate sheet and the punch, and a pouchshaped
battery case manufacturing method using the same.
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【Background Art】
[3] Demand for a secondary battery as an energy
source for mobile devices and electric vehicles has
abruptly increased. In particular, demand for a lithium
secondary battery, which has high energy density and
discharge voltage, is very high.
[4] Based on the shape thereof, the lithium secondary
battery may be classified as a cylindrical battery, a
prismatic battery, or a pouch-shaped battery. The pouchshaped
battery has advantages in that the pouch-shaped
battery can be stacked with high degree of integration,
has high energy density per unit weight, is inexpensive,
and is easily deformable. The pouch-shaped battery uses
a laminate sheet as a battery case and is configured to
have a structure in which an electrode assembly is
received in a receiving portion formed in the laminate
sheet together with an electrolytic solution.
[5] The receiving portion of the pouch-shaped battery
is formed by pressing a soft laminate sheet through deep
drawing using a punch in the state in which the sheet is
fixed. During deep drawing, external defects, such as
pin-holes or cracks, are formed on the outer surface of
the laminate sheet due to limited softness of the
laminate sheet and frictional force applied upon pressing
using the punch.
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[6] Even though surface roughness of the punch that
contacts the laminate sheet is extremely reduced,
frictional force is generated due to continuous work,
whereby external defects are generated. Particularly, in
the case in which the laminate sheet is configured to
have a small thickness, shapeability of the sheet is
reduced, whereby external defects are frequently
generated. For this reason, there is limitation in
manufacturing a large-capacity secondary battery by
reducing the thickness of the battery case in order to
increase the thickness of the electrode assembly.
[7] In order to solve this problem, various attempts
have been made. For example, a separate film is added to
the laminate sheet, or the laminate sheet is punched
twice or more.
[8] Patent Document 1 relates to a warm working
method of stainless steel foil and a mold for warm
working, wherein austenite-based stainless steel foil
having a thickness of 300 μm or less is disposed so as to
face a punch, and stainless steel foil is drawn in the
state in which a ring-shaped region of the stainless
steel foil that a shoulder of the punch contacts is
maintained at a temperature of 30°C or less and a region
of the stainless steel foil outside the ring-shaped
region is maintained at a temperature of 40°C to 100°C.
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[9] Patent Document 1 uses a heating method for
drawing but does not disclose whether a lubricant is
volatile and, furthermore, a method of removing the
lubricant. For the pouch-shaped battery, the
electrolytic solution directly contacts the laminate
sheet. In the case in which the lubricant remains on the
surface of the laminate sheet, therefore, performance of
the secondary battery may be adversely affected.
[10] Also, in Patent Document 1, stainless steel is
processed. In order to increase softness of a metal,
temperature may be raised. However, a laminate sheet
according to the present invention has a problem in that
temperature cannot be raised due to resin layers attached
to inner and outer surfaces of the laminate sheet.
[11] Patent Document 2 relates to a method of forming
a compacted and pressed body including the following
steps: a step of preparing raw material powder; a step of
providing a lubricant for pressing between the outer
circumferential surface of a first punch and the inner
circumferential surface of a die and moving the first
punch and the die relative to each other in this state to
apply the lubricant for pressing to the inner
circumferential surface of the die; a step of filling a
cavity with the raw material powder and pressing the raw
material powder to form a compacted and pressed body,
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wherein, in an application process, the lubricant for
pressing is applied to the inner circumferential surface
of the die while the lubricant for pressing is discharged
through a supply port formed in the first punch and the
discharged lubricant for pressing is collected through a
discharge port formed in the first punch.
[12] In Patent Document 2, the lubricant is supplied
through a separate supply unit and is collected through a
separate collection unit. In Patent Document 2, the
material to be processed is powder, and therefore a
lubricant capable of surviving for a predetermined time
is inevitably necessary in order to reduce frictional
force between powder particles that may be generated
during the pressing process, and a means capable of
collecting the lubricant must be provided. The material
to be pressed in Patent Document 2 is powder, which is
very different from the laminate sheet used in the
present invention in terms of physical properties.
[13] Patent Document 3 relates to a rolling tool, and
more particularly to a rolling tool for machining the
inner surface of a cylindrical gap in a lateral direction,
particularly for smooth surface rolling. The rolling
tool disclosed in Patent Document 3 includes at least one
rolling body provided in the rolling tool, which is
rotatable, the rolling body being picked by the tool
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along the inner surface of the cylindrical gap in the
lateral direction. In this case, the at least one
rolling body may be inserted into the gap of the rolling
tool in a radial direction and may be put under a fluid
pressurized from inside to outside along the gap in the
radial direction. In Patent Document 3, an aerosol is
used as the fluid. The aerosol of Patent Document 3 is a
fluid mixed with gas and is used for a static bearing and
lubrication. This aerosol type lubricant is used in a
specific technical field and is irrelevant to the
laminate sheet shaping apparatus according to the present
invention.
[14] Patent Document 4 relates to a battery case
shaping apparatus including a low-friction punch head,
which is an apparatus for forming a battery case
including an electrode assembly receiving portion in
which an electrode assembly is received. The shaping
apparatus of Patent Document 4 includes a die having a
depressed type or penetrated type open recess having a
size corresponding to an electrode assembly receiving
portion, a sheet base material for manufacture of a
battery case being located at the upper surface of the
die, a punch having a shape corresponding to the open
recess, the punch being located above the open recess to
perform deep drawing with respect to the sheet base
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material, the punch including a punch head configured to
be introduced into the open recess when being moved
downwards, the punch head being made of a low
coefficient of friction material, and a holder
configured to press opposite ends of the sheet base
material so as to be fixed to the die for deep drawing.
[15] As previously described, in the case in which
strength of a material is high, heat is generated due to
continuous working even though surface roughness is
reduced to lower frictional force, whereby external
defects, such as pin-holes or cracks, are formed in the
laminate sheet. In Patent Document 4, frictional force
is lowered, and the punch is made of a resin, such as
polytetrafluoroethylene, in order to prevent occurrence
of wrinkles and efflorescence at a corner of the
receiving portion at the time of deep drawing.
[16] The laminate sheet has been used as a case of the
pouch-shaped battery for a long time; however, this is
technology suitable to manufacture a pouch-shaped battery
suitable for past markets. A shaping apparatus having a
low defect rate while providing for a high-capacity
battery based on a recent market environment change and a
pouch-shaped battery case manufacturing method using the
same have not yet been suggested.
[17] Korean Patent Application Publication No. 2015-
8
0060797 (2015.06.03) “Patent Document 1”
[18] Korean Patent Application Publication No. 2014-
0089377 (2014.07.14) “Patent Document 2”
[19] Korean Patent Application Publication No. 2016-
0032280 (2016.03.23) “Patent Document 3”
[20] Korean Patent Application Publication No. 2018-
0028194 (2018.03.16) “Patent Document 4”
【Disclosure】
【Technical Problem】
[21] The present invention has been made in view of
the above problems, and it is an object of the present
invention to provide an effective pouch-shaped battery
case shaping apparatus capable of, in shaping a pouchshaped
battery case:
[22] 1) minimizing surface damage that may occur at
the outer surface of a laminate sheet;
[23] 2) preventing formation of pin-holes or cracks
when shaping a thin laminate sheet;
[24] 3) without making significant changes to a
conventional shaping apparatus and a method using the
same;
[25] 4) using a conventional laminate sheet without
change; and
[26] 5) preventing the presence of residuals after
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shaping, and a pouch-shaped battery case manufacturing
method using the same.
【Technical Solution】
[27] In order to accomplish the above object, the
present invention provides a pouch-shaped battery case
shaping apparatus including:
[28] a die having a depressed type or penetrated type
open recess having a size corresponding to an electrode
assembly receiving portion, a sheet being located at the
upper surface of the die; a punch having a shape
corresponding to the open recess, the punch being
located above the open recess to perform deep drawing
with respect to the sheet, the punch including a punch
head configured to be introduced into the open recess
when being moved downwards; a holder configured to press
opposite ends of the sheet so as to be fixed to the die
for deep drawing; and a lubricant supply unit configured
to supply a lubricant to the upper surface of the sheet
that abuts the punch head.
[29] The pouch-shaped battery case shaping apparatus
may not lack a separate lubricant collection unit
configured to collect the lubricant supplied to the upper
surface of the sheet, and the lubricant supply unit may
be configured to supply the lubricant to only a portion
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of the sheet that is drawn.
[30] The lubricant according to the present invention
may be a no-clean lubricant or a volatile lubricant, e.g.
a lubricant that is volatile by heat generated due to
shaping or at normal temperature when remaining after
processing. The volatile lubricant according to the
present invention does not require a separate degreasing
process. In order to improve lubricity, a very small
amount of oily agent may be mixed. The volatile
lubricant according to the present invention may be more
rapidly dried through air blowing or using hot air.
[31] A lubricant is used in conventional metal
pressing. The outer layer of the laminate sheet
according to the present invention is a resin layer. In
the case in which a lubricant, particularly a volatile
lubricant, is used in conventional metal pressing, a
problem may occur. The volatile lubricant may exhibit
properties similar to properties of a detergent due to
high volatility thereof, and may easily penetrate the
resin layer, whereby the surface of the laminate sheet
may be stained. Stained products are discarded as
defective products.
[32] Consequently, a lubricant that does not permeate
the resin layer must be used. In this case, however,
volatility of the lubricant is low, and therefore a
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separate washing process is needed after processing.
[33] The present invention has been made in view of a
problem when shaping is performed using such a volatile
lubricant and provides a pouch-shaped battery case
shaping apparatus configured such that an injection
nozzle and a punch are disposed so as to be very close to
each other, a volatile lubricant is supplied immediately
before shaping, and the lubricant is removed through air
blowing or using hot air after shaping.
[34] As a result, it is possible to solve a problem
in that defects such as stains, occur and to prevent
damage, such as pin-holes or cracks, which may occur at
the time of shaping.

【Claim 1】 A pouch-shaped battery case shaping
apparatus comprising:
a die having a depressed type or penetrated type
open recess having a size corresponding to an electrode
assembly receiving portion, a sheet being located at an
upper surface of the die;
a punch having a shape corresponding to the open
recess, the punch being located above the open recess to
perform deep drawing with respect to the sheet, the
punch comprising a punch head configured to be
introduced into the open recess when being moved
downwards;
a holder configured to press opposite ends of the
sheet so as to be fixed to the die for deep drawing; and
a lubricant supply unit configured to supply a
lubricant to an upper surface of the sheet that abuts
the punch head.
【Claim 2】 The pouch-shaped battery case shaping
apparatus according to claim 1, wherein the pouch-shaped
battery case shaping apparatus lacks a separate lubricant
collection unit configured to collect the lubricant
supplied to the upper surface of the sheet.
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【Claim 3】 The pouch-shaped battery case shaping
apparatus according to claim 1, wherein the lubricant
supply unit is configured to supply the lubricant to
only a portion of the sheet that is drawn.
【Claim 4】 The pouch-shaped battery case shaping
apparatus according to claim 1, wherein the lubricant is
a volatile lubricant.
【Claim 5】 The pouch-shaped battery case shaping
apparatus according to claim 1, wherein the sheet
comprises a laminate sheet.
【Claim 6】 The pouch-shaped battery case shaping
apparatus according to claim 1, wherein a portion of the
punch head that abuts the sheet is made of at least a
low coefficient of friction material.
【Claim 7】 The pouch-shaped battery case shaping
apparatus according to claim 1, wherein a portion of the
punch head that abuts the sheet comprises at least a
temperature adjustment unit configured to raise or lower
temperature.
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【Claim 8】 The pouch-shaped battery case shaping
apparatus according to claim 1, wherein the lubricant
supply unit comprises an injection nozzle configured to
inject a lubricant in an aerosol state.
【Claim 9】 The pouch-shaped battery case shaping
apparatus according to claim 8, wherein the injection
nozzle is fixed to the holder.
【Claim 10】 A pouch-shaped battery case manufacturing
method using the pouch-shaped battery case shaping
apparatus according to any one of claims 1 to 9, the
pouch-shaped battery case manufacturing method comprising:
(S1) disposing the sheet between the die and the
punch;
(S2) applying the lubricant to a portion of the
sheet that contacts the punch head; and
(S3) shaping the sheet into the battery case using
the punch.
【Claim 11】 The pouch-shaped battery case manufacturing
method according to claim 10, wherein the lubricant is
simultaneously applied to a surface of the punch head
and a surface of the sheet.
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【Claim 12】 The pouch-shaped battery case manufacturing
method according to claim 11, wherein step (S2) is
includes injecting a lubricant in an aerosol state.
【Claim 13】 The pouch-shaped battery case manufacturing
method according to claim 12, wherein the injection
nozzle fixed to the holder injects the lubricant in the
aerosol state.