【Technical Field】
[1] This application claims the benefit of priority
to Korean Patent Application No. 2020-0070046 filed on
June 10, 2020, the disclosure of which is incorporated
herein by reference in its entirety.
[2] The present invention relates to a method of
manufacturing an electrode including a folding portion
and an electrode sheet including the folding portion, and
more particularly to a method of manufacturing an
electrode including a folding portion usable to
manufacture a foldable battery cell and an electrode
sheet including the folding portion.
【Background Art】
[3] A lithium secondary battery, which is capable of
being charged and discharged, has been widely used as an
energy source for wireless mobile devices or wearable
devices, and has also been used as an energy source for
electric vehicles and hybrid electric vehicles presented
as alternatives to existing gasoline and diesel vehicles,
2
which cause air pollution.
[4] In addition, with an increase in kinds of
miniaturized multifunctional products and a trend of
emphasizing design in electronic devices, the number of
products based on new shapes, such as a shape including a
curve or a geometrical shape, other than conventional
simple structures, such as a planar structure and a
prismatic structure, has increased.
[5] Lithium secondary batteries having various shapes,
such as a stepped shape and a polygonal shape, other than
a rectangular shape, have been developed in order to
apply the lithium secondary batteries to such products
having various shapes.
[6] For example, for a smartphone, the side thereof
is curved in order to improve sensation of grip, and
flexible display products capable of being bent or folded
have come on the stage.
[7] In the case in which a rectangular battery cell
is used in a bendable or foldable device, there is a
problem in that dead space is formed in many instances.
Therefore, it is necessary to develop a battery cell
capable of securing capacity while reducing dead space
even though the battery cell is mounted in a device
having an atypical shape.
[8] In connection therewith, Patent Document 1
3
discloses a secondary battery configured such that a
positive electrode active material layer and a negative
electrode active material layer are formed by coating so
as to be spaced apart from each other by a predetermined
distance and including a bending region configured to be
bent at an uncoated portion, which is not coated with the
positive electrode active material layer and the negative
electrode active material layer.
[9] The secondary battery disclosed in Patent
Document 1 is suitably applied to a long device but has a
problem in that a plurality of bending regions is formed,
whereby the uncoated portion is widened, and therefore
energy density is lowered.
[10] Patent Document 2 relates to a battery cell
including a current collector having at least one
uncoated portion that partitions an electrode mixture,
wherein the portion of a battery case at which the
uncoated portion is located is bent, whereby the shape of
the battery cell is changed.
[11] In Patent Document 2, an electrode assembly is
separated from the battery case, whereby there is a
problem in that a bent portion of the battery case and a
bent portion of the electrode assembly may be misaligned
with each other when the battery cell is bent.
[12] Patent Document 3 discloses an electrode
4
configured to have a structure in which an electrode
active material is printed on a band type electrode
current collector so as to have a pattern repeated at
regular intervals.
[13] However, the invention disclosed in Patent
Document 3 relates to an electrode cut so as to have a
predetermined length and width, wherein the electrode is
received in a sheathing member in a state of being bent.
[14] As can be seen from the above description, each
of the above patent documents discloses only an electrode
including an uncoated portion that is coated with no
electrode mixture. Therefore, a method of manufacturing
an electrode having the above structure or research on
the shape of an electrode sheet is needed.
[15] (Prior Art Documents)
[16] (Patent Document 1) Korean Patent Application
Publication No. 2012-0022385 (2012.03.12)
[17] (Patent Document 2) Korean Patent Application
Publication No. 2017-0033513 (2017.03.27)
[18] (Patent Document 3) Japanese Patent Application
Publication No. 1995-153438 (1995.06.16)
【Disclosure】
【Technical Problem】
[19] The present invention has been made in view of
5
the above problems, and it is an object of the present
invention to provide a method of manufacturing an
electrode including a folding portion constituted by an
uncoated portion having no electrode mixture formed
thereon by coating in order to manufacture an electrode
for foldable battery cells and an electrode sheet
including the folding portion.
【Technical Solution】
[20] An electrode manufacturing method according to
the present invention to accomplish the above object
includes a coating step of forming an electrode mixture
coated portion on an electrode sheet so as to include an
uncoated portion having no electrode mixture formed
thereon by coating; a step of slitting the electrode
sheet into a plurality of unit electrode sheets; and a
step of notching the slit electrode sheet, wherein the
uncoated portion includes an electrode tab formation
portion and a folding portion formed so as to be
parallel to a direction in which the electrode sheet is
taken out.
[21] In the electrode manufacturing method according
to the present invention, the coated portion may be
continuously formed so as to be parallel to the
direction in which the electrode sheet is taken out.
6
[22] In the electrode manufacturing method according
to the present invention, the slitting step may be a step
of slitting a coated portion located between the folding
portion and another folding portion adjacent to the
folding portion.
[23] The electrode manufacturing method according to
the present invention may include a step of forming the
uncoated portion such that the width of the electrode
tab formation portion and the width of the folding
portion are different from each other.
[24] In the electrode manufacturing method according
to the present invention, the notching step may include a
notching process for forming an electrode tab at the
electrode tab formation portion and a process of
notching the electrode sheet along a notching line to
divide the electrode sheet into the plurality of unit
electrode sheets.
[25] In addition, the notching process for forming
the electrode tab and the process of notching the
electrode sheet along the notching line may be
simultaneously performed.
[26] In the electrode manufacturing method according
to the present invention, the electrode tab formation
portion may be formed at each of opposite side ends and
a middle portion of the electrode sheet that is taken
7
out.
[27] The electrode sheet may be slit into the
plurality of unit electrode sheets having two different
widths.
[28] An electrode sheet according to the present
invention includes a coated portion having an electrode
mixture coated thereon and an uncoated portion having no
electrode mixture formed thereon by coating, wherein the
uncoated portion includes an electrode tab formation
portion and a folding portion formed so as to be
parallel to a direction in which the electrode sheet is
taken out.
[29] In the electrode sheet according to the present
invention, the coated portion, the electrode tab
formation portion, and the folding portion may be formed
so as to be symmetrical with respect to a slitting line.
[30] In the electrode sheet according to the present
invention, the folding portion may be an uncoated
portion formed between the slitting line and the
electrode tab formation portion.
[31] In the electrode sheet according to the present
invention, a first coated portion and a second coated
portion may be formed on opposite sides of the folding
portion, and the first coated portion and the second
coated portion may be formed so as to have the same size.
8
[32] In the electrode sheet according to the present
invention, the width of the folding portion may be
greater than the thickness of the coated portion x π.
[33] In addition, the present invention provides a
battery cell including an electrode manufactured using
the electrode manufacturing method, wherein the battery
cell is configured to be bendable at the folding portion
of the electrode.
【Advantageous Effects】
[34] As is apparent from the above description, in an
electrode manufacturing method according to the present
invention, in order to form not only an uncoated portion,
which is an electrode tab formation portion, but also an
uncoated portion, which is configured to manufacture a
folded electrode, on an electrode sheet, a method of
coating a portion of the electrode sheet with an
electrode mixture is used, whereby it is possible to
reduce the number of manufacturing steps as compared to
a method of coating the entirety of the electrode sheet
with the electrode mixture and then removing the coating
and to reduce defects that may occur during a coating
removal process.
[35] Also, in a notching process for manufacturing a
unit electrode, notching is performed such that a folding
9
portion is included in the unit electrode, whereby it is
possible to obtain a unit electrode having a coated
portion and an uncoated portion formed so as to have
regular areas.
[36] In addition, it is possible to manufacture a
foldable battery cell using an electrode assembly
including an electrode according to the present invention,
and therefore it is possible to provide a battery cell
usable in a device having a bent or curved shape.
【Description of Drawings】
[37] FIG. 1 is a plan view of an electrode sheet
according to an embodiment.
[38] FIG. 2 is a plan view of an electrode sheet
according to another embodiment.
[39] FIG. 3 is a plan view showing a notching portion
formed in the electrode sheet of FIG. 1.
[40] FIG. 4 is a vertical sectional view of the
electrode sheet of FIG. 3.
【Best Mode】
[41] 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
10
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.
[42] 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.
[43] Embodiments of the present invention will be
described in detail with reference to the accompanying
drawings.
[44] FIG. 1 is a plan view of an electrode sheet
according to an embodiment.
[45] Referring to FIG. 1, the electrode sheet 100 is
taken out in an arrow direction, and FIG. 1 shows a
11
start part of the electrode sheet that is taken out.
[46] An electrode manufacturing method according to
the present invention includes a coating step of forming
an electrode mixture coated portion on an electrode
sheet so as to include an uncoated portion having no
electrode mixture formed thereon by coating, a step of
slitting the electrode sheet into a plurality of unit
electrode sheets, and a step of notching the slit
electrode sheet.
[47] Referring to FIG. 1, an electrode mixture coated
portion 110 is formed at the electrode sheet 100 while
the electrode sheet is taken out in an arrow direction.
At this time, the coated portion 110 is formed such that
an uncoated portion having no electrode mixture formed
thereon by coating is formed.
[48] The coated portion 110 may be formed at any one
of the upper surface and the lower surface of the
electrode sheet or may be formed at opposite surfaces of
the electrode sheet.
[49] The uncoated portion includes an electrode tab
formation portion 120 and a folding portion 130 formed
so as to extend in a direction parallel to a direction
in which the electrode sheet is taken out.
[50] In the electrode sheet according to the present
invention, the uncoated portion and the coated portion
12
are continuously formed in the direction parallel to the
direction in which the electrode sheet is taken out.
[51] A slitting line 140 is formed at the middle of
the electrode sheet 100 in the direction in which the
electrode sheet is taken out, and the coated portion 110,
the electrode tab formation portion 120, and the folding
portion 130 are formed so as to be symmetrical with
respect to the slitting line 140.
[52] The slitting line means a preliminary cutting
line along which a cutter moves in order to divide the
coated portion in the slitting step.
[53] The slitting step is performed through a process
of slitting a coated portion 110 located between a
folding portion 130 and another folding portion 130
adjacent to the folding portion. At this time, in order
to produce electrodes having uniform sizes, the slitting
line 140 is set at a position at which the coated
portion 110 is divided into two equal parts.
[54] The folding portion 130 is an uncoated portion
formed between the slitting line 140 and the electrode
tab formation portion 120. In the case in which a
battery cell including an electrode assembly
manufactured using unit electrodes formed through the
slitting and notching steps is manufactured and then
folded, the folding portion is set to be an uncoated
13
portion having no electrode mixture formed thereon by
coating in order to prevent the electrode mixture from
being separated from an electrode current collector.
[55] Meanwhile, in order to prevent a positive
electrode tab and a negative electrode tab from
contacting each other in a stacking direction when a
positive electrode and a negative electrode formed
through slitting and notching are stacked in the state
in which a separator is interposed therebetween, the
electrode tab may be formed so as to be biased to one
side from the outer periphery of the electrode from
which the electrode tab protrudes. As shown in FIG. 1,
therefore, electrode tabs formed at opposite sides of
the electrode tab formation portion 120 in the direction
in which the electrode sheet is taken out are formed so
as not to overlap.
[56] The present invention relates to an electrode
manufacturing method for manufacturing an electrode that
is folded on the basis of an x-axis and an electrode
sheet, wherein a first coated portion 110a and a second
coated portion 110b are formed at opposite sides of a
unit electrode 101 formed through slitting and notching
on the basis of the folding portion 130.
[57] When the electrode is folded, the first coated
portion 110a and the second coated portion 110b face
14
each other, and therefore the first coated portion and
the second coated portion may be formed so as to have
the same size.
[58] FIG. 2 is a plan view of an electrode sheet
according to another embodiment.
[59] Referring to FIG. 2, the electrode sheet 200 is
taken out in an arrow direction, and FIG. 2 shows a
start part of the electrode sheet that is taken out.
[60] Unlike the electrode sheet of FIG. 1, the
electrode sheet of FIG. 2 is configured to have a
structure in which an electrode tab formation portion
220a is formed at each of opposite side ends of the
electrode sheet 200 that is taken out and in which an
electrode tab formation portion 220b is formed at a
middle portion of the electrode sheet.
[61] In addition, a coated portion 210, a folding
portion 230, and a coated portion 210 are sequentially
formed from the electrode tab formation portion 220a in
an inward direction of the electrode sheet 200.
[62] That is, the coated portions 210 are formed on
opposite sides of the folding portion 230, and this form
may be expressed as a coated portion 210 having a
folding portion 230 formed at the middle thereof.
[63] In addition, a coated portion 210 including a
folding portion 230 is formed at each of the upper part
15
and the lower part of the electrode sheet on the basis
of the electrode tab formation portion 220b at the
middle portion of the electrode sheet in the direction
in which the electrode sheet is taken out.
[64] The electrode sheet 200 has a structure in which
the electrode sheet is slit along two slitting lines 240
to form three unit electrode sheets 251, 252, and 253.
The unit electrode sheet 251 and the unit electrode
sheet 253 have the same width, and the width of the unit
electrode sheet 252 is formed so as to be greater than
the width of each of the unit electrode sheets 251 and
253. Consequently, in the structure in which the
electrode tab formation portions are formed at opposite
side ends and the middle portion of the electrode sheet,
as in the electrode sheet 200, unit electrode sheets
having two kinds of widths are formed.
[65] The slitting step is performed using a method of
forming a slitting line 240 at the coated portion 210
located between the folding portions 230 and slitting
the coated portion along the slitting line 240.
[66] FIG. 3 is a plan view showing a notching portion
formed in the electrode sheet of FIG. 1.
[67] Referring to FIG. 3, the notching step includes
a notching process for forming an electrode tab 102 at
the electrode tab formation portion 120 and a process of
16
notching the electrode sheet along a notching line 122
in order to divide the electrode sheet into unit
electrode sheets 150.
[68] The slitting line 140 that divides the electrode
sheet 100 into a plurality of unit electrode sheets 150
is formed on the coated portion 110, and the notching
line 122 is formed so as to be perpendicular to the
slitting line 140 and is formed in the shape of a
straight line passing through the coated portion 110 and
the folding portion 130.
[69] The notching process for forming the electrode
tab and the process of notching the electrode sheet
along the notching line may be sequentially performed.
Alternatively, the notching process for forming the
electrode tab and the process of notching the electrode
sheet along the notching line may be simultaneously
performed.
[70] In the case in which the notching process for
forming the electrode tab and the process of notching
the electrode sheet along the notching line are
simultaneously performed, it is possible to reduce an
electrode manufacturing time.
[71] FIG. 4 is a vertical sectional view of the
electrode sheet of FIG. 3.
[72] Referring to FIG. 4, FIG. 4 is a vertical
17
sectional view of the electrode sheet cut in the x-axis
of FIG. 3.
[73] The uncoated portion may be formed such that the
width W1 of the electrode tab formation portion 120 and
the width W2 of the folding portion 130 are different
from each other. For example, when considering a
structure in which electrode tabs are not formed so as
to overlap each other, the width W1 of the electrode tab
formation portion 120 may be formed so as to be less
than the width W2 of the folding portion 130.
Alternatively, the width W1 of the electrode tab
formation portion 120 may be formed so as to be greater
than the width W2 of the folding portion 130 depending
on the sizes of the electrode tabs.
[74] The folding portion 130 is disposed so as to
face each other in the state in which the electrode is
folded. It is preferable for the width W2 of the
folding portion 130 to be at least 1/2 of the
circumference of a circle having the thickness H of the
coated portion as a radius. Consequently, the width W2
of the folding portion 130 may be formed so as to be
greater than the thickness H of the coated portion x π.
[75] Those skilled in the art to which the present
invention pertains will appreciate that various
applications and modifications are possible within the
18
category of the present invention based on the above
description.
[76] (Description of Reference Symbols)
[77] 100, 200: Electrode sheets
[78] 101: Unit electrode
[79] 102: Electrode tab
[80] 110, 210: Coated portions
[81] 110a: First coated portion
[82] 110b: Second coated portion
[83] 120, 220a, 220b: Electrode tab formation portions
[84] 122: Notching line
[85] 130, 230: Folding portions
[86] 140, 240: Slitting lines
[87] 150, 251, 252, 253: Unit electrode sheets
[88] H: Thickness of coated portion
[89] W1: Width of electrode tab formation portion
[90] W2: Width of folding portion
【Industrial Applicability】
[91] As is apparent from the above description, in an
electrode manufacturing method according to the present
invention, in order to form not only an uncoated portion,
which is an electrode tab formation portion, but also an
uncoated portion, which is configured to manufacture a
folded electrode, on an electrode sheet, a method of
19
coating a portion of the electrode sheet with an
electrode mixture is used, whereby it is possible to
reduce the number of manufacturing steps as compared to
a method of coating the entirety of the electrode sheet
with the electrode mixture and then removing the coating
and to reduce defects that may occur during a coating
removal process.
[92] Also, in a notching process for manufacturing a
unit electrode, notching is performed such that a folding
portion is included in the unit electrode, whereby it is
possible to obtain a unit electrode having a coated
portion and an uncoated portion formed so as to have
regular areas.
[93] Also, it is possible to manufacture a foldable
battery cell using an electrode assembly including an
electrode according to the present invention, and
therefore it is possible to provide a battery cell usable
in a device having a bent or curved shape.

【Claim 1】 An electrode manufacturing method
comprising:
a coating step of forming an electrode mixture
coated portion on an electrode sheet so as to include an
uncoated portion having no electrode mixture formed
thereon by coating;
a step of slitting the electrode sheet into a
plurality of unit electrode sheets; and
a step of notching the slit electrode sheet,
wherein the uncoated portion comprises:
an electrode tab formation portion; and
a folding portion formed so as to be parallel to a
direction in which the electrode sheet is taken out.
【Claim 2】 The electrode manufacturing method
according to claim 1, wherein the coated portion is
continuously formed so as to be parallel to the
direction in which the electrode sheet is taken out.
【Claim 3】 The electrode manufacturing method
according to claim 1, wherein the slitting step is a
step of slitting a coated portion located between the
folding portion and another folding portion adjacent to
21
the folding portion.
【Claim 4】 The electrode manufacturing method
according to claim 1, comprising a step of forming the
uncoated portion such that a width of the electrode tab
formation portion and a width of the folding portion are
different from each other.
【Claim 5】 The electrode manufacturing method
according to claim 1, wherein the notching step
comprises:
a notching process for forming an electrode tab at
the electrode tab formation portion; and
a process of notching the unit electrode sheets
along a notching line to divide the unit electrode
sheets.
【Claim 6】 The electrode manufacturing method
according to claim 5, wherein the notching process for
forming the electrode tab and the process of notching
the unit electrode sheets along the notching line are
simultaneously performed.
【Claim 7】 The electrode manufacturing method
according to claim 1, wherein the electrode tab
22
formation portion is formed at each of opposite side
ends and a middle portion of the electrode sheet that is
taken out.
【Claim 8】 The electrode manufacturing method
according to claim 7, wherein the electrode sheet is
slit into the plurality of unit electrode sheets having
two different widths.
【Claim 9】 An electrode sheet comprising:
a coated portion having an electrode mixture coated
thereon; and
an uncoated portion having no electrode mixture
formed thereon by coating,
wherein the uncoated portion comprises:
an electrode tab formation portion; and
a folding portion formed so as to be parallel to a
direction in which the electrode sheet is taken out.
【Claim 10】 The electrode sheet according to claim 9,
wherein the coated portion, the electrode tab formation
portion, and the folding portion are formed so as to be
symmetrical with respect to a slitting line.
【Claim 11】 The electrode sheet according to claim 10,
23
wherein the folding portion is an uncoated portion
formed between the slitting line and the electrode tab
formation portion.
【Claim 12】 The electrode sheet according to claim 10,
wherein a first coated portion and a second coated
portion are formed on opposite sides of the folding
portion, and
wherein the first coated portion and the second
coated portion are formed so as to have an identical
size.
【Claim 13】 The electrode sheet according to claim 9,
wherein a width of the folding portion is greater than a
thickness of the coated portion x π.
【Claim 14】 A battery cell comprising an electrode
manufactured using the electrode manufacturing method
according to any one of claims 1 to 8, wherein the
battery cell is configured to be bendable at the folding
portion of the electrode.