【DESCRIPTION】
【Invention Title】
ELECTRODE ASSEMBLY MANUFACTURING APPARATUS INCLUDING
ULTRASONIC CUTTER AND ELECTRODE ASSEMBLY MANUFACTURING
METHOD USING THE SAME
【Technical Field】
[1] This application claims the benefit of priority
to Korean Patent Application No. 2020-0117858 filed on
September 14, 2020, the disclosure of which is
incorporated herein by reference in its entirety.
[2] The present invention relates to an electrode
assembly manufacturing apparatus including an ultrasonic
cutter and an electrode assembly manufacturing method
using the same. More particularly, the present invention
relates to an electrode assembly manufacturing apparatus
including an ultrasonic cutter capable of cutting an
electrode mixture coating portion as well as an electrode
mixture non-coating portion in order to form an electrode
tab at an electrode sheet and an electrode assembly
manufacturing method using the same.
【Background Art】
[3] A secondary battery, which is capable of being
repeatedly charged and discharged, has an advantage in
2
that lifespan of a battery cell is long, and is used in a
form in which the secondary battery is detachably
attached to a device or is built in a device. The kinds
of devices using the secondary battery as an energy
source have increased.
[4] In particular, a lithium secondary battery, which
is charged and discharged as the result of movement of
lithium ions, has been used not only in the field of a
small-sized battery cell, which is used for mobile
devices or small-sized electronic products, but also in
the field of a medium- or large-sized battery pack, which
is used as an energy source of an electric vehicle or a
power storage system that requires high output and high
voltage, since the lithium secondary battery has
advantages of high energy density and high charge voltage.
[5] Based on the shape of a battery case, the lithium
secondary battery is classified as a cylindrical
secondary battery having an electrode assembly mounted in
a cylindrical metal can, a prismatic secondary battery
having an electrode assembly mounted in a prismatic metal
can, or a pouch-shaped secondary battery having an
electrode assembly mounted in a pouch-shaped case made of
an aluminum laminate sheet.
[6] The electrode assembly is formed by stacking a
positive electrode and a negative electrode such that a
3
separator is interposed therebetween, and the positive
electrode and the negative electrode are manufactured
through a process of forming an electrode tab at each of
a positive electrode sheet and a negative electrode sheet
and a process of cutting each of the positive electrode
sheet and the negative electrode sheet into a unit
electrode.
[7] Conventionally, a method of removing the
remaining part of a non-coating portion of the electrode
sheet excluding the electrode tab by punching is used to
form the electrode tab.
[8] Specifically, a press cutter including an upper
cutter and a lower cutter is placed on the electrode
sheet, and the electrode sheet is notched by punching
using the upper cutter to form the electrode tab. In the
case in which the press cutter including the upper cutter
and the lower cutter is used, however, the distance
between the upper cutter and the lower cutter must be
maintained at 0. As a result, much time is taken to
maintain the press cutter. Furthermore, an electrode
mixture layer may be easily cracked and the electrode
mixture layer may be separated from the electrode sheet
by pressure applied to the electrode sheet at the time of
punching.
[9] In addition, a burr may be generated on the cut
4
section of an electrode sheet foil, or the cut section of
the electrode sheet foil may be deformed, whereby quality
of the cut section of the electrode sheet foil may be
deteriorated.
[10] In addition, since vibration is generated during
a punching process using the press cutter, the electrode
sheet having the electrode tab formed thereat by notching
is wound in the form of a roll and the wound electrode
sheet is conveyed to a lamination process line in order
to perform a lamination process. Since the notching
process and the lamination process must be separately
performed, as described above, it is necessary to secure
a wide space necessary for electrode assembly production
facilities, and it is difficult to automate the entire
process for manufacturing the electrode assembly.
[11] In connection therewith, Patent Document 1
discloses an ultrasonic cutting device configured to cut
a portion of a precursor of a secondary battery including
a plurality of stacked power generation elements, each of
which includes a positive electrode having a positive
electrode protrusion for terminal connection, a separator,
and a negative electrode having a negative electrode
protrusion for terminal connection, e.g. a stack of the
positive electrode protrusion and the negative electrode
protrusion.
5
[12] The ultrasonic cutting device of Patent Document
1 cuts the positive electrode protrusion and the negative
electrode protrusion in the state in which the power
generation elements are stacked. However, a method of
cutting a positive electrode and a negative electrode
from an electrode sheet is not provided, and the
ultrasonic cutting device cuts only non-coating portions
of the positive electrode and the negative electrode.
[13] Therefore, there is a need for an electrode sheet
cutter capable of preventing separation of an electrode
mixture layer and deformation of an electrode sheet foil
at the time of cutting an electrode mixture coating
portion.
[14] (Prior Art Document)
[15] (Patent Document 1) Japanese Patent Application
Publication No. 2018-09468 (2018.06.21)
【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 an electrode assembly manufacturing
apparatus capable of reducing a facility space necessary
to manufacture an electrode assembly while preventing
deformation of an electrode sheet foil and damage to an
6
electrode mixture coating portion during a process of
cutting an electrode sheet having a step formed due to
the electrode mixture coating portion and an electrode
assembly manufacturing method using the same.
【Technical Solution】
[17] In order to accomplish the above object, an
electrode assembly manufacturing apparatus according to
the present invention includes an electrode sheet supply
unit configured to supply an electrode sheet having an
electrode mixture coating portion and an electrode
mixture non-coating portion formed thereon, a cutting
unit disposed at the rear of the electrode sheet supply
unit, the cutting unit being configured to form an
electrode tab at the electrode sheet, and a lamination
unit disposed at the rear of the electrode sheet supply
unit, the lamination unit being configured to laminate a
positive electrode and a negative electrode stacked with
a separator interposed between the positive and the
negative electrodes, wherein the cutting unit includes a
die configured to support the electrode sheet and an
ultrasonic cutter spaced apart from the die, the
ultrasonic cutter being configured to form the electrode
tab, a cutting line of a cutting edge of the ultrasonic
cutter is formed so as to correspond to an outer
7
periphery of a unit electrode in a direction in which the
electrode tab is formed, and the cutting unit and the
lamination unit are disposed on the same process line
such that a continuous process is performed.
[18] In the electrode assembly manufacturing apparatus
according to the present invention, the ultrasonic cutter
may further include an auxiliary cutting edge configured
to form a recess configured to guide unit electrode
cutting.
[19] The electrode assembly manufacturing apparatus
according to the present invention may further include an
electrode formation unit disposed between the cutting
unit and the lamination unit, the electrode formation
unit being configured to cut the electrode sheet in order
to manufacture the unit electrode.
[20] In the electrode assembly manufacturing apparatus
according to the present invention, the cutting line of
the cutting edge of the ultrasonic cutter may be formed
so as to correspond to the outer periphery of the unit
electrode.
[21] In the electrode assembly manufacturing apparatus
according to the present invention, the ultrasonic cutter
may be configured to cut the electrode mixture coating
portion.
[22] In the electrode assembly manufacturing apparatus
8
according to the present invention, the cutting line of
the cutting edge of the ultrasonic cutter may be formed
in a uniform plane.
[23] In the electrode assembly manufacturing apparatus
according to the present invention, an inspection member
may be coupled to the ultrasonic cutter.
[24] In addition, the present invention provides an
electrode assembly manufacturing method using the
electrode assembly manufacturing apparatus.
[25] Specifically, the electrode assembly
manufacturing method may include (a) conveying an
electrode sheet to the cutting unit, (b) forming the
electrode tab using the ultrasonic cutter, (c) cutting
the electrode sheet into a unit electrode, and (d)
laminating the positive electrode and the negative
electrode with each other in the state in which the
separator is interposed between the positive and the
negative electrodes, wherein step (a) to step (d) may be
performed on a continuous process line.
[26] In the electrode assembly manufacturing method
according to the present invention, step (b) and step (c)
may be simultaneously performed.
[27] In the electrode assembly manufacturing method
according to the present invention, step (b) and step (c)
may be sequentially performed, step (b) may be performed
9
using a first ultrasonic cutter, and step (c) may be
performed using a second ultrasonic cutter.
[28] In the electrode assembly manufacturing method
according to the present invention, the vibration
direction of the ultrasonic cutter may be a direction
perpendicular to the electrode sheet.
[29] In the electrode assembly manufacturing method
according to the present invention, step (b) may include
forming a recess configured to guide unit electrode
cutting.
[30] In the electrode assembly manufacturing method
according to the present invention, step (b) may include
pushing the cutting edge of the ultrasonic cutter once in
the state in which the cutting edge of the ultrasonic
cutter is placed on the outer surface of the electrode
sheet to form the outer periphery of a unit electrode in
the direction in which the electrode tab is formed.
【Advantageous Effects】
[31] As is apparent from the above description, in the
present invention, an ultrasonic cutter is used to form
an electrode tab, whereby it is possible to prevent
deformation of an electrode sheet foil or separation of
an electrode mixture layer in the cut section of an
electrode mixture coating portion as well as an electrode
10
mixture non-coating portion.
[32] In addition, a cutting unit configured to form an
electrode tab and a lamination unit are disposed on the
same process line such that a continuous process can be
performed, whereby it is possible to reduce space
necessary for electrode assembly manufacturing facilities.
[33] Also, in the case in which an inspection member
is coupled to the ultrasonic cutter, it is possible to
inspect the cut section of an electrode sheet having an
electrode tab formed thereat simultaneously with
formation of the electrode tab.
【Description of Drawings】
[34] FIG. 1 is a perspective view of an electrode
assembly manufacturing apparatus according to a first
embodiment.
[35] FIG. 2 is a perspective view of an ultrasonic
cutter according to the present invention.
[36] FIG. 3 is an enlarged view of a cutting edge of
the ultrasonic cutter.
[37] FIG. 4 is a plan view showing various shapes of
the cutting edge.
[38] FIG. 5 is a partial enlarged view showing the
portion of a positive electrode sheet at which a
positive electrode tab is formed.
11
[39] FIG. 6 is a perspective view of a portion of an
electrode assembly manufacturing apparatus according to a
second embodiment.
[40] FIG. 7 is a perspective view of a portion of an
electrode assembly manufacturing apparatus according to a
third embodiment.
[41] FIG. 8 is a perspective view showing a cutting
edge in an electrode assembly manufacturing apparatus
according to a fourth embodiment.
[42] FIG. 9 is an enlarged view of the cut section of
an electrode sheet cut using a press cutter.
[43] FIG. 10 is a plan view of the electrode sheet
cut using the press cutter.
[44] FIG. 11 is an enlarged view of the cut section
of an electrode sheet cut using the ultrasonic cutter.
[45] FIG. 12 is a plan view of the electrode sheet
cut using the ultrasonic cutter.
[46] FIG. 13 is a view showing comparison between
sections of a positive electrode sheet having an
insulative coating added thereto notched using a press
and the ultrasonic cutter.
[47] FIG. 14 is a view showing comparison between
sections of a negative electrode sheet notched using the
press, the ultrasonic cutter, and a laser.
12
【Best Mode】
[48] Now, preferred embodiments of the present
invention will be described in detail with reference to
the accompanying drawings such that the preferred
embodiments of the present invention can be easily
implemented by a person having ordinary skill in the art
to which the present invention pertains. In describing
the principle of operation of the preferred embodiments
of the present invention in detail, however, a detailed
description of known functions and configurations
incorporated herein will be omitted when the same may
obscure the subject matter of the present invention.
[49] In addition, the same reference numbers will be
used throughout the drawings to refer to parts that
perform similar functions or operations. In the case in
which one part is said to be connected to another part
throughout the specification, not only may the one part
be directly connected to the other part, but also, the
one part may be indirectly connected to the other part
via a further part. In addition, that a certain element
is included does not mean that other elements are
excluded, but means that such elements may be further
included unless mentioned otherwise.
[50] In addition, a description to embody elements
through limitation or addition may be applied to all
13
inventions, unless particularly restricted, and does not
limit a specific invention.
[51] Also, in the description of the invention and the
claims of the present application, singular forms are
intended to include plural forms unless mentioned
otherwise.
[52] Also, in the description of the invention and the
claims of the present application, “or” includes “and”
unless mentioned otherwise. Therefore, “including A or B”
means three cases, namely, the case including A, the case
including B, and the case including A and B.
[53] Embodiments of the present invention will be
described in detail with reference to the accompanying
drawings.
[54] FIG. 1 is a perspective view of an electrode
assembly manufacturing apparatus according to a first
embodiment, and FIG. 2 is a perspective view of an
ultrasonic cutter according to the present invention.
[55] FIG. 1 shows a process of manufacturing a monocell
configured to have a structure in which one
positive electrode and one negative electrode are
stacked in the state in which a separator is interposed
therebetween.
[56] Referring to FIGS. 1 and 2, the electrode
assembly manufacturing apparatus 10 includes an electrode
14
sheet supply unit 100 configured to supply an electrode
sheet having an electrode mixture coating portion and an
electrode mixture non-coating portion formed thereon; a
cutting unit 200 configured to form an electrode tab at
the electrode sheet; and a lamination unit 300 configured
to laminate a positive electrode and a negative electrode
stacked such that a separator is interposed therebetween.
[57] The cutting unit 200 includes an ultrasonic
cutter 210 and a die 220. An electrode tab is formed at
an electrode sheet that moves above the die 220 using the
ultrasonic cutter 210.
[58] The ultrasonic cutter 210 shown in FIG. 2
includes an oscillator 212 configured to generate
ultrasonic waves, a booster 213 configured to
amplify/reduce vibration energy generated by the
oscillator 212, a cutting edge 211 configured to cut an
electrode sheet, and a horn 214 configured to transmit
the vibration energy from the booster 213 to the cutting
edge 211.
[59] In a concrete example, the cutting speed of the
ultrasonic cutter 210 may be set to 200 m/s or less. The
ultrasonic waves of the ultrasonic cutter may have an
oscillation frequency of 15 kHz to 40 kHz and an
amplitude of 10 μm to 60 μm, which may be changed
depending on the construction of the electrode sheet.
15
[60] In the present invention, as described above, the
ultrasonic cutter is used to form an electrode tab, and
therefore damage to an electrode sheet due to vibration
is less than in a conventional process of notching an
electrode tab by punching using a press cutter.
[61] Also, in the case in which a conventional cutting
unit cuts an electrode sheet using the press cutter, the
distance between an upper cutter and a lower cutter must
be maintained at 0, and therefore a micro-adjustment
process for maintaining the distance between the upper
cutter and the lower cutter is necessary. In the present
invention, however, an electrode tab is formed by pushing
the cutting edge of the ultrasonic cutter in the state in
which the cutting edge is placed on the outer surface of
the electrode sheet, and therefore a process of
maintaining the distance between the upper cutter and the
lower cutter is unnecessary, unlike the conventional art.
Consequently, it is possible to save time necessary to
maintain the distance between the upper cutter and the
lower cutter in the conventional art.
[62] Meanwhile, vibration generated during the
notching process using the press cutter is great in the
conventional art. If the notching process and a
lamination process of aligning and laminating a positive
electrode and a negative electrode are performed on the
16
same process line, therefore, vibration generated during
the notching process may affect the lamination process.
In the conventional art, therefore, a notching process
line and a lamination process line are separately
provided. Specifically, an electrode assembly is
manufactured using a method of winding an electrode
sheet that has undergone the notching process in the
form of a roll, conveying the wound electrode sheet to
the lamination process line, and performing the
lamination process. Consequently, the notching process
and the lamination process are discontinuously performed.
[63] In the present invention, however, the ultrasonic
cutter, which generates little vibration, is used during
a process of forming an electrode tab. Even though the
cutting unit and the lamination unit are disposed on the
same process line, therefore, vibration from the cutting
unit hardly affects the lamination unit. In the present
invention, therefore, the cutting unit and the
lamination unit are disposed on the same process line,
whereby the electrode tab formation process and the
lamination process may be continuously performed.
[64] Consequently, a facility space necessary to
manufacture an electrode assembly may be reduced. In
addition, since time for conveying an electrode roll is
unnecessary, it is possible to reduce time necessary to
17
manufacture the electrode assembly and to automate the
notching process and the lamination process.
[65] For example, in the case in which the notching
process and the lamination process are continuously
performed on the same process line, it is possible to
reduce about 5% to 50% of time necessary when the
notching process and the lamination process are
discontinuously performed.
[66] In a concrete example, an inspection member 215
is attached to the ultrasonic cutter 210 of FIG. 2 so as
to face in a direction parallel to the cutting edge 211.
A vision camera may be used as the inspection member 215.
[67] In the case in which the press cutter is used in
the conventional art, it is difficult to provide the
inspection member at the press cutter due to impact
generated during a cutting process. However, the
present invention proposes a structure in which the
inspection member is attached to the ultrasonic cutter,
whereby it is possible to determine whether the shape of
an electrode tab is normal simultaneously with cutting of
an electrode sheet. Consequently, an electrode assembly
manufacturing process may be shortened, whereby
productivity may be improved.
[68] The electrode sheet supply unit 100 of FIG. 1
includes a positive electrode sheet supply unit
18
configured to supply a positive electrode sheet 110 and a
negative electrode sheet supply unit configured to supply
a negative electrode sheet 120.
[69] The positive electrode sheet 110 is provided with
a positive electrode mixture coating portion 111, in
which opposite surfaces of a positive electrode sheet
foil 113 are coated with a positive electrode mixture,
and a positive electrode mixture non-coating portion 112,
in which no positive electrode mixture is formed on the
opposite surfaces of the positive electrode sheet foil
113 by coating. That is, the positive electrode mixture
non-coating portion 112 is an exposed portion of the
positive electrode sheet foil 113.
[70] The description of the positive electrode sheet
110 having the positive electrode mixture coating portion
111 and the positive electrode mixture non-coating
portion 112, in which no positive electrode mixture is
formed by coating, is equally applied to a negative
electrode sheet 120 having a negative electrode mixture
coating portion 121 and a negative electrode mixture noncoating
portion 122, in which no negative electrode
mixture is formed by coating.
[71] Referring to FIGS. 1 and 2, a cutting line 216
of the cutting edge 211 of the ultrasonic cutter 210 of
FIG. 2 is formed so as to correspond to the outer
19
periphery of a unit electrode in a direction in which an
electrode tab is formed.
[72] When the cutting edge 211 of the ultrasonic
cutter is disposed at a position at which an electrode
tab is to be formed and an electrode sheet is pressed
using the ultrasonic cutter, therefore, the remaining
part of the positive electrode mixture non-coating
portion 112 excluding a positive electrode tab 114 is cut
along the shape of the cutting line 216, whereby the
positive electrode tab 114 is formed, and the remaining
part of the negative electrode mixture non-coating
portion 122 excluding a negative electrode tab 124 is cut
along the shape of the cutting line 216, whereby the
negative electrode tab 124 is formed.
[73] An electrode formation unit 400, which is
configured to cut the positive electrode sheet having the
positive electrode tab 114 formed thereat in order to
manufacture a unit positive electrode and which is
configured to cut the negative electrode sheet having the
negative electrode tab 124 formed thereat in order to
manufacture a unit negative electrode, is located at the
rear of the cutting unit 200. That is, the electrode
formation unit 400 is disposed between the cutting unit
200 and the lamination unit 300.
[74] The unit positive electrode and the unit negative
20
electrode mean a single positive electrode and a single
negative electrode manufactured by cutting the positive
electrode sheet and the negative electrode sheet at
predetermined intervals. In this specification, the
positive electrode is used as a meaning including the
unit positive electrode, and the negative electrode is
used as a meaning including the unit negative electrode.
[75] In the electrode formation unit 400, a cutter
410 configured to cut the electrode sheet may be a press
cutter including an upper cutter and a lower cutter, or
an ultrasonic cutter may be used.
[76] In the case in which the ultrasonic cutter is
used, it is possible to cut the electrode sheet such that
damage to the electrode mixture layer and the electrode
sheet foil is minimized.
[77] The unit positive electrodes and the unit
negative electrodes cut by the electrode formation unit
are conveyed to the lamination unit 300 in a state of
being attached to a separator 150 so as to be spaced
apart from each other by a predetermined distance. A
positive electrode 131 attached to the separator 150 and
a negative electrode 132 attached to the separator 150
are laminated with each other while passing between a
pair of rollers 310 included in the lamination unit 300.
Subsequently, a separator cutting process is performed,
21
whereby a mono-cell having a structure in which the
positive electrode, the separator, the negative
electrode, and the separator are sequentially stacked is
manufactured.
[78] In a concrete example, an electrode assembly
manufacturing method according to the present invention
may include (a) a step of conveying an electrode sheet
to the cutting unit, (b) a step of forming an electrode
tab using the ultrasonic cutter, (c) a step of cutting
the electrode sheet into a unit electrode, and (d) a step
of laminating a positive electrode and a negative
electrode with each other in the state in which a
separator is interposed therebetween, wherein step (a)
to step (d) may be performed on a continuous process
line.
[79] As shown in FIG. 1, step (b) performed at the
cutting unit 200 and step (c) performed at the electrode
formation unit 400 may be sequentially performed. In
step (b), the ultrasonic cutter 210 may be used as a
first ultrasonic cutter. In step (c), the cutter 410 may
be used as a second ultrasonic cutter.
[80] The vibration direction of the ultrasonic cutter
210 is a direction perpendicular to the positive
electrode sheet 110 and the negative electrode sheet 120.
Consequently, the ultrasonic cutter 210 is moved in a
22
direction perpendicular to the positive electrode sheet
and the negative electrode sheet such that the movement
direction of the ultrasonic cutter is identical to the
vibration direction of the ultrasonic cutter.
[81] In connection therewith, FIG. 3 is an enlarged
view of the cutting edge of the ultrasonic cutter.
[82] Referring to FIG. 3, the cutting line 216 of the
cutting edge 211 of the ultrasonic cutter is bent so as
to correspond in shape to the outer periphery of a unit
electrode at which an electrode tab is formed.
[83] Referring to an enlarged sectional view of the
cutting edge taken along line A-A’, the end of the
section of the cutting edge is formed in a V shape.
Consequently, the cutting edge must be moved in a state
of being perpendicular to the electrode sheet such that
the electrode sheet is cut by the end of the cutting
edge. In this case, contact between the cutting edge
and the electrode sheet may be minimized, whereby
friction therebetween may be minimized. If the cutting
edge is moved in a state of being inclined relative to
the electrode sheet, not perpendicular to the electrode
sheet, in order to cut the electrode sheet, the
electrode sheet may be burned due to friction generated
as the result of contact between the V-shaped inclined
surface of the end of the cutting edge and the electrode
23
sheet.
[84] Meanwhile, the cutting line of the cutting edge
of the ultrasonic cutter is formed in a uniform plane.
That is, the length of the cutting edge in a y-axis
direction is uniform over the entirety thereof.
[85] In connection therewith, FIG. 4 is a plan view
showing various shapes of the cutting edge.
[86] Referring to (a) to (c) of FIG. 4, the length of
the cutting edge in the y-axis direction is not uniform.
That is, cutting lines 236, 246, and 256 of the cutting
edge are not formed in a uniform plane.
[87] In the case in which an electrode sheet is cut
using the press cutter including the upper cutter and
the lower cutter in the conventional art, the cutting
edge having any of the above-mentioned shapes is used in
order to increase cutting force. When the electrode
sheet is cut using the cutting edges shown in (a) to (c)
of FIG. 4, however, the cutting edges must be further
moved by h1, h2, and h3 in the y-axis direction.
[88] In contrast, the movement distance of the
cutting edge used in the present invention in the y-axis
direction is reduced by h1, h2, and h3, compared to the
cutting edges shown in FIG. 4, and therefore it is
possible to reduce time necessary to form the electrode
tab, compared to the case in which the conventional
24
press cutter is used.
[89] FIG. 5 is a partial enlarged view showing the
portion of the positive electrode sheet at which the
positive electrode tab is formed.
[90] Referring to FIG. 5, the positive electrode
sheet is cut such that an outer periphery 115 of the
positive electrode is formed at the part of the positive
electrode shifted toward the positive electrode mixture
coating portion 111 by G based on a border line 116
between the positive electrode mixture coating portion
111 and the positive electrode mixture non-coating
portion 112.
[91] That is, the ultrasonic cutter cuts not only the
positive electrode mixture non-coating portion 112, at
which the positive electrode tab 114 is formed, but also
the positive electrode mixture coating portion 111.
[92] FIG. 6 is a perspective view of a portion of an
electrode assembly manufacturing apparatus according to a
second embodiment.
[93] Referring to FIG. 6, a positive electrode sheet
110 supplied from an electrode sheet supply unit 100 is
provided with a positive electrode mixture coating
portion 111 and a positive electrode mixture non-coating
portion 112, and a positive electrode tab 114 is formed
at the positive electrode mixture non-coating portion 112
25
and a border between the positive electrode mixture
coating portion 111 and the positive electrode mixture
non-coating portion 112.
[94] Two cutting edges 211 of an ultrasonic cutter 210
are continuously disposed, which is different from FIG. 1.
The speed at which the positive electrode tab is formed
may be increased in proportion to extension of the
cutting edge 211.
[95] FIG. 7 is a perspective view of a portion of an
electrode assembly manufacturing apparatus according to a
third embodiment.
[96] Referring to FIG. 7, the ultrasonic cutter
further includes an auxiliary cutting edge 219, when
compared to FIG. 1. The auxiliary cutting edge 219 is
provided to form a recess configured to guide unit
electrode cutting. A recess configured to indicate the
position at which the electrode sheet is cut in order to
manufacture a unit electrode may be formed.
[97] The recess may be formed so as to have a slit
shape or a shape in which the size of the recess is
gradually increased from the inside to the outside of
the electrode sheet, although the shape of the recess is
not particularly restricted. Specifically, a V-shaped
recess may be formed.
[98] Consequently, cutting for forming an electrode
26
tab and cutting for forming a recess configured to guide
unit electrode cutting may be simultaneously performed,
whereby the manufacturing process may be shortened.
[99] FIG. 8 is a perspective view showing a cutting
edge in an electrode assembly manufacturing apparatus
according to a fourth embodiment.
[100] Referring to FIG. 8, a cutting line 266 of the
cutting edge 231 is formed in a shape corresponding to
the outer periphery of a positive electrode 131.
[101] When the cutting edge of FIG. 8 is used, a step
of forming an electrode tab using an ultrasonic cutter
and a step of cutting an electrode sheet into a unit
electrode may be simultaneously performed. Consequently,
it is possible to separate a positive electrode 131
having a positive electrode tab formed thereat from a
positive electrode sheet by pressing the electrode sheet
once. Therefore, the separate electrode formation unit
of FIG. 1 is not necessary.
[102] Consequently, it is possible to simplify the
electrode assembly manufacturing process and to reduce
manufacturing time.
[103] In order to determine whether an electrode sheet
is damaged in the case in which the electrode assembly
manufacturing apparatus according to the present
invention is used, an electrode obtained by cutting the
27
electrode sheet using the ultrasonic cutter and an
electrode obtained by cutting the electrode sheet using
the press cutter are compared with each other as follows.
[104] FIG. 9 is an enlarged view of the cut section of
an electrode sheet cut using the press cutter, and FIG.
10 is a plan view of the electrode sheet cut using the
press cutter. FIG. 11 is an enlarged view of the cut
section of an electrode sheet cut using the ultrasonic
cutter, and FIG. 12 is a plan view of the electrode
sheet cut using the ultrasonic cutter.
[105] Referring to FIGS. 9 and 10, it can be seen from
the cut section of the electrode sheet cut using the
press cutter shown in FIG. 9 that an electrode sheet
foil 511 was bent and an electrode mixture layer 512 was
separated from the electrode sheet foil 511. In
addition, it can be seen from a portion indicated by a
dotted line in FIG. 10 that the electrode mixture layer
512 was separated from the electrode sheet foil 511.
[106] Referring to FIGS. 11 and 12 using the ultrasonic
cutter, it can be seen that both of an electrode sheet
foil 611 and an electrode mixture layer 612 were not
deformed at the cut section of the electrode sheet and
that the electrode mixture layer 612 was normally
attached to the electrode sheet foil 611.
[107] FIG. 13 is a view showing comparison between
28
sections of a positive electrode sheet having an
insulative coating added thereto notched using a press
and the ultrasonic cutter.
[108] Referring to FIG. 13, it can be seen that the
insulative coating was separated from the positive
electrode notched using the press, as shown in a circle
indicated by a dotted line. However, it can be seen
that the positive electrode notched using the ultrasonic
cutter had a neat external appearance without separation
of the insulative coating layer and that a smooth border
line of the positive electrode mixture layer was
maintained, i.e. the positive electrode mixture layer
was stably attached to the positive electrode sheet foil.
[109] FIG. 14 is a view showing comparison between
sections of a negative electrode sheet notched using the
press, the ultrasonic cutter, and a laser.
[110] Referring to FIG. 14, it can be seen that, when
press notching was performed, an electrode tab was bent
and a burr was generated on an electrode sheet foil 711
in the cut section of the positive electrode sheet. It
can be seen that, when laser notching was performed, an
electrode mixture layer 712 in the cut section of an
electrode tab and the notching section were thermally
deformed by heat from the laser. It can be seen that,
when notching was performed using the ultrasonic cutter,
29
the electrode sheet foil 711 and the electrode mixture
layer 712 were not damaged in both the electrode tab and
the notching section, the electrode sheet foil 711 was
not bent even in the cut section, and the electrode
mixture layer 712 was normally attached to the electrode
sheet foil 711.

【CLAIMS】
【Claim 1】 An electrode assembly manufacturing
apparatus comprising:
an electrode sheet supply unit configured to supply
an electrode sheet having an electrode mixture coating
portion and an electrode mixture non-coating portion
formed thereon;
a cutting unit disposed at a rear of the electrode
sheet supply unit, the cutting unit being configured to
form an electrode tab at the electrode sheet; and
a lamination unit disposed at a rear of the
electrode sheet supply unit, the lamination unit being
configured to laminate a positive electrode and a
negative electrode stacked with a separator interposed
between the positive and the negative electrodes,
wherein the cutting unit comprises a die configured
to support the electrode sheet and an ultrasonic cutter
spaced apart from the die, the ultrasonic cutter being
configured to form the electrode tab,
wherein a cutting line of a cutting edge of the
ultrasonic cutter is formed so as to correspond to an
outer periphery of a unit electrode in a direction in
which the electrode tab is formed, and
wherein the cutting unit and the lamination unit are
33
disposed on an identical process line such that a
continuous process is performed.
【Claim 2】 The electrode assembly manufacturing
apparatus according to claim 1, wherein the ultrasonic
cutter further comprises an auxiliary cutting edge
configured to form a recess configured to guide unit
electrode cutting.
【Claim 3】 The electrode assembly manufacturing
apparatus according to claim 1, further comprising an
electrode formation unit disposed between the cutting
unit and the lamination unit, the electrode formation
unit being configured to cut the electrode sheet in order
to manufacture the unit electrode.
【Claim 4】 The electrode assembly manufacturing
apparatus according to claim 1, wherein the cutting line
of the cutting edge of the ultrasonic cutter is formed so
as to correspond to the outer periphery of the unit
electrode.
【Claim 5】 The electrode assembly manufacturing
apparatus according to claim 1, wherein the ultrasonic
cutter is configured to cut the electrode mixture coating
34
portion.
【Claim 6】 The electrode assembly manufacturing
apparatus according to claim 1, wherein the cutting line
of the cutting edge of the ultrasonic cutter is formed in
a uniform plane.
【Claim 7】 The electrode assembly manufacturing
apparatus according to claim 1, wherein an inspection
member is coupled to the ultrasonic cutter.
【Claim 8】 An electrode assembly manufacturing method
using the electrode assembly manufacturing apparatus
according to any one of claims 1 to 7, the electrode
assembly manufacturing method comprising:
(a) conveying an electrode sheet to the cutting
unit;
(b) forming the electrode tab using the ultrasonic
cutter;
(c) cutting the electrode sheet into a unit
electrode; and
(d) laminating the positive electrode and the
negative electrode with each other in a state in which
the separator is interposed between the positive and the
negative electrodes,
35
wherein step (a) to step (d) are performed on a
continuous process line.
【Claim 9】 The electrode assembly manufacturing method
according to claim 8, wherein step (b) and step (c) are
simultaneously performed.
【Claim 10】 The electrode assembly manufacturing method
according to claim 8, wherein
step (b) and step (c) are sequentially performed,
step (b) is performed using a first ultrasonic
cutter, and
step (c) is performed using a second ultrasonic
cutter.
【Claim 11】 The electrode assembly manufacturing method
according to claim 8, wherein a vibration direction of
the ultrasonic cutter is a direction perpendicular to the
electrode sheet.
【Claim 12】 The electrode assembly manufacturing method
according to claim 8, wherein step (b) comprises forming
a recess configured to guide unit electrode cutting.
【Claim 13】 The electrode assembly manufacturing method
36
according to claim 8, wherein step (b) includes pushing
the cutting edge of the ultrasonic cutter once in a state
in which the cutting edge of the ultrasonic cutter is
placed on an outer surface of the electrode sheet to form
an outer periphery of the unit electrode in a direction
in which the electrode tab is formed.