【Technical Field】
[1] This application claims the benefit of priority
to Korean Patent Application No. 2020-0137864 filed on
October 22, 2020, the disclosure of which is incorporated
herein by reference in its entirety.
[2] The present invention relates to a battery case
shaping apparatus and a battery case manufacturing method
using the same. More particularly, the present invention
relates to a battery case shaping apparatus including a
punch configured to shape a battery case for pouch-shaped
batteries, wherein the battery case shaping apparatus
further includes an elastic separator capable of, when a
laminate sheet that is used as the battery case is
pressed by the punch, minimizing damage to the surface of
the laminate sheet, and a battery case manufacturing
method using the same.
【Background Art】
[3] Demand for a secondary battery as an energy
source for mobile devices, electric vehicles, etc. has
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abruptly increased. In particular, demand for a lithium
secondary battery, which has high energy density and high
discharge voltage, is high.
[4] Based on the shape and material thereof, the
lithium secondary battery may be classified as a
cylindrical secondary battery made of a metal material, a
prismatic secondary battery made of a metal material, or
a pouch-shaped secondary battery made of a laminate sheet.
The pouch-shaped secondary battery has advantages in that
the pouch-shaped secondary battery is stacked with high
degree of integration, thereby having high energy density
per unit weight, is manufactured at low cost, and is
easily deformable. Consequently, the pouch-shaped
secondary battery is used in various devices.
[5] The pouch-shaped secondary battery uses a
laminate sheet including an outer coating layer, a metal
blocking layer, and an inner adhesive layer 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.
[6] In order to shape an electrode assembly receiving
portion in the pouch-shaped secondary battery, a deep
drawing method of disposing a laminate sheet on a die,
fixing the laminated sheet using a gripper, and pressing
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the laminate sheet using a punch is used. During deep
drawing, however, 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
the force of friction between the punch and the laminate
sheet.
[7] Even though surface roughness of the punch that
contacts the laminate sheet is extremely reduced in order
to prevent formation of such external defects, it is
difficult to prevent external defects from being formed
on the laminate sheet due to friction caused by repeated
punching. Particularly, in the case in which the
thickness of the laminate sheet, specifically the metal
blocking layer, is small, shapeability of the laminate
sheet is reduced, whereby pin-holes or cracks may be more
easily formed. For this reason, it is difficult to shape
the electrode assembly receiving portion so as to have a
large depth, whereby it is difficult to manufacture a
high-capacity lithium secondary battery.
[8] Patent Document 1 discloses a sheathing member
for batteries, the sheathing member including an outer
layer including a heat-resistant resin film, a metal foil
layer, and an inner layer including a thermoplastic resin
film having a lubricant added thereto, wherein the
lubricant is attached between the outer layer and the
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inner layer.
[9] In Patent Document 1, the lubricant is attached
between the outer layer and the inner layer, whereby
sliding of the outer layer relative to a second die and
sliding of the inner layer relative to a first die are
improved, and therefore it is possible to inhibit bending
of the outer circumferential portion of the sheathing
member for batteries.
[10] Patent Document 2 discloses a packaging material
for shaping including a substrate layer, as an outer
layer, a thermally fusible resin layer, as an inner layer,
and a metal foil layer disposed between the two layers,
wherein the thermally fusible resin layer is configured
to have a single layer structure or a multilayer
structure, and the innermost layer of the thermally
fusible resin layer is made of a resin composition
containing an anti-blocking agent, a slip agent, and a
fluoropolymer-based lubricant.
[11] In Patent Document 2, slip between the surface of
the innermost layer of the thermally fusible resin layer
and the surface of a shaping die is improved when the
packaging material is shaped, whereby shapeability may be
improved.
[12] Patent Document 1 and Patent Document 2 do not
recognize a problem in that defects are generated as the
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result of the sheathing member for batteries being
elongated during drawing, and do not suggest a method of
solving the problem.
[13] Therefore, there is a high necessity for
technology capable of preventing damage to the external
appearance of a laminate sheet and improving shapeability
during shaping of the laminate sheet.
[14] Japanese Registered Patent Publication No.
5959205 (2016.07.07) (“Patent Document 1”)
[15] Korean Patent Application Publication No. 2020-
0027987 (2020.03.13) (“Patent Document 2”)
【Disclosure】
【Technical Problem】
[16] The present invention has been made in view of
the above problems, and it is an object of the present
invention to provide a battery case shaping apparatus
capable of reducing the force of friction between a punch
configured to press a laminate sheet in order to shape a
battery case and the laminate sheet due to contact
therebetween, thereby preventing damage to the laminate
sheet, and a battery case shaping method using the same.
【Technical Solution】
[17] In order to accomplish the above object, a
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battery case shaping apparatus according to the present
invention includes a punch configured to press a laminate
sheet in order to shape a battery case, a die in which an
accommodation portion is formed, the accommodation
portion having a size corresponding to an electrode
assembly receiving portion that is shaped by the punch, a
holder configured to fix the outer periphery of the
laminate sheet, and an elastic separator located under
the punch in order to prevent direct contact between the
punch and the laminate sheet.
[18] In the battery case shaping apparatus according
to the present invention, the elastic separator may be
fixed to the holder.
[19] In the battery case shaping apparatus according
to the present invention, the elastic separator may be
fixed to a lower part of the side surface of the holder.
[20] In the battery case shaping apparatus according
to the present invention, the lower surface of the punch
may be configured to be parallel to the upper surface of
the elastic separator before the battery case is shaped
by the punch.
[21] In the battery case shaping apparatus according
to the present invention, a liquid lubricant may be added
into a space formed by the elastic separator and the
holder.
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[22] In the battery case shaping apparatus according
to the present invention, a recess may be formed in at
least a portion of the lower surface of the punch.
[23] In the battery case shaping apparatus according
to the present invention, a pad may be disposed in and at
a lower part of the accommodation portion of the die.
[24] In the battery case shaping apparatus according
to the present invention, the pad may be made of an
elastic material and may include a central part that
convexly protrudes.
[25] In the battery case shaping apparatus according
to the present invention, the protruding central part of
the pad may be configured to contract as the result of
pressing by the punch, whereby the overall thickness of
the pad may become uniform.
[26] In the battery case shaping apparatus according
to the present invention, the elastic separator may be a
watertight elastic separator.
[27] The present invention provides a battery case
shaping method using the battery case shaping apparatus.
[28] Specifically, the battery case shaping method may
include (a) disposing the laminate sheet on the die, (b)
fixing the laminate sheet to the die using the holder
having the elastic separator attached to the holder, and
(c) pressing the elastic separator and the laminate
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sheet using the punch.
[29] The battery case shaping method according to the
present invention may further include adding a liquid
lubricant into a space formed by the elastic separator
and the holder between step (b) and step (c).
[30] In the battery case shaping method according to
the present invention, in step (c), the pressing may be
performed until the pad disposed in the lower part of
the accommodation portion of the die is compressed and
flat.

【CLAIMS】
【Claim 1】 A battery case shaping apparatus comprising:
a punch configured to press a laminate sheet in
order to shape a battery case;
a die in which an accommodation portion is formed,
the accommodation portion having a size corresponding to
an electrode assembly receiving portion that is shaped by
the punch;
a holder configured to fix an outer periphery of the
laminate sheet; and
an elastic separator located under the punch in
order to prevent direct contact between the punch and
the laminate sheet.
【Claim 2】 The battery case shaping apparatus
according to claim 1, wherein the elastic separator is
fixed to the holder.
【Claim 3】 The battery case shaping apparatus
according to claim 2, wherein the elastic separator is
fixed to a lower part of a side surface of the holder.
【Claim 4】 The battery case shaping apparatus
according to claim 1, wherein, a lower surface of the
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punch is configured to be parallel to an upper surface
of the elastic separator before the battery case is
shaped by the punch.
【Claim 5】 The battery case shaping apparatus
according to claim 2, wherein a liquid lubricant is
added into a space formed by the elastic separator and
the holder.
【Claim 6】 The battery case shaping apparatus
according to claim 1, wherein a recess is formed in at
least a portion of a lower surface of the punch.
【Claim 7】 The battery case shaping apparatus
according to claim 1, wherein a pad is disposed in and
at a lower part of the accommodation portion of the die.
【Claim 8】 The battery case shaping apparatus
according to claim 7, wherein the pad is made of an
elastic material and includes a central part that
convexly protrudes.
【Claim 9】 The battery case shaping apparatus
according to claim 7, wherein the protruding central
part of the pad is configured to contract as a result of
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pressing by the punch, whereby an overall thickness of
the pad becomes uniform.
【Claim 10】 The battery case shaping apparatus
according to claim 1, wherein the elastic separator is a
watertight elastic separator.
【Claim 11】 A battery case shaping method using the
battery case shaping apparatus according to any one of
claims 1 to 10, the battery case shaping method
comprising:
(a) disposing the laminate sheet on the die;
(b) fixing the laminate sheet to the die using the
holder having the elastic separator attached to the
holder; and
(c) pressing the elastic separator and the laminate
sheet using the punch.
【Claim 12】 The battery case shaping method according
to claim 11, further comprising adding a liquid
lubricant into a space formed by the elastic separator
and the holder between step (b) and step (c).
【Claim 13】 The battery case shaping method according
to claim 11, wherein, in step (c), the pressing is
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performed until the pad disposed in the lower part of
the accommodation portion of the die is compressed and
flat.
【Claim 14】 The battery case shaping method according
to claim 13, wherein, when compression of the pad starts,
liquid lubricant moves to an edge of the lower surface
of the punch.
【Claim 15】 The battery case shaping method according
to claim 11, wherein a region of the laminate sheet that
is elongated by the pressing in step (c) is a side
surface of the electrode assembly receiving portion and
an outer circumferential portion of a bottom of the
electrode assembly receiving portion.
【Claim 16】 A battery case manufactured using the
battery case shaping apparatus according to any one of
claims 1 to 10, wherein a thickness of a smallest
thickness portion of the battery case is 70% or more of a
thickness of a largest thickness portion of the battery
case.