TECHNICAL FIELD
Cross-reference to Related Applications
[0001] This application claims priority from Korean Patent
Application Nos. 10-2020-0036393, filed on March 25, 2020,
and 10-2021-0008932, filed on January 21, 2021, the
disclosures of which are incorporated by reference herein.
Technical Field
[0002] The present invention relates to unit cell
preparation apparatus and method, and more particularly, to
unit cell preparation apparatus and method which may prevent
a displacement in position of an upper electrode when the
upper electrode is stacked on a stack that is formed by
stacking a center electrode and a separator.
BACKGROUND ART
[0003] In general, types of secondary batteries include a
nickel cadmium battery, a nickel hydride battery, a lithium
ion battery, and a lithium ion polymer battery. These
secondary batteries are not only applied and used in small
products such as digital cameras, P-DVDs, MP3Ps, mobile
phones, PDAs, portable game devices, power tools, and E-bikes,
but are also applied and used in large products requiring
high output, such as electric vehicles and hybrid vehicles,
and a power storage device and a power storage device for
backup which store surplus generated power or renewable
energy.
[0004] In order to prepare such a secondary battery, first,
2
a positive electrode collector and a negative electrode
collector are respectively coated with electrode active
material slurries to prepare a positive electrode and a
negative electrode, and the positive electrode and the
negative electrode are then stacked on both sides of a
separator to form an electrode assembly having a
predetermined shape. Then, after the electrode assembly is
accommodated in a battery case and an electrolyte solution is
injected, the battery case is sealed.
[0005] The electrode assembly is classified into various
types. For example, there are a simple stack type in which a
unit cell is not prepared and positive electrodes, separators,
and negative electrodes are simply crossed and continuously
stacked, a lamination & stack type (L&S) in which a unit cell
is first prepared using a positive electrode, a separator,
and a negative electrode and these unit cells are then
stacked, a stack & folding type (S&F) in which a plurality of
electrodes or unit cells are spaced apart and attached to one
surface of a separator sheet having a greater length in one
side and the separator sheet is repeatedly folded in the same
direction from one end, and a Z-folding type that
alternatingly repeats a process in which a plurality of
electrodes or unit cells are alternatingly attached to one
surface and the other surface of a separator sheet having a
greater length in one side and the separator sheet is folded
in a specific direction from one end and then folded in an
opposite direction.
[0006] Among them, in order to prepare the lamination &
stack type (L&S) electrode assembly, first, a unit cell must
be prepared. In general, in order to prepare the unit cell,
3
separators are respectively stacked on upper and lower
surfaces of a center electrode while the center electrode is
moved to one side by a conveyor belt or the like, and
thereafter, an upper electrode is further stacked on an
uppermost end. In addition, in some cases, a lower electrode
may be further stacked on a lowermost end. Then, a
laminating process is performed in which heat and pressure
are applied to a stack in which the electrodes and the
separators are stacked. Since the laminating process is
performed, the electrodes and the separators may be bonded
together to firmly form a unit cell.
[0007] However, typically, the laminating process was
performed after the lower separator, the center electrode,
the upper separator, and the upper electrode were all stacked.
Accordingly, since an overall thickness was large, heat was
not transferred to the inside of the stack, and thus, there
was a problem in that adhesion was reduced. Particularly,
the adhesion was reduced at an interface between the
innermost center electrode and the upper separator, and,
accordingly, since the electrode and the separator were not
adhered to each other, there was a problem in that the
electrode was out of position.
[0008] [Prior Art Documents] Korean Patent Application Laid-
Open Publication No. 2014-0022620
DISCLOSURE OF THE INVENTION
TECHNICAL PROBLEM
[0009] An aspect of the present invention provides unit cell
preparation apparatus and method which may prevent a
displacement in position of an upper electrode when the upper
electrode is stacked on a stack that is formed by stacking a
4
center electrode and separator sheets.
[0010] The object of the present invention is not limited to
the aforesaid, but other objects not described herein will be
clearly understood by those skilled in the art from
descriptions below.
TECHNICAL SOLUTION
[0011] According to an aspect of the present invention,
there is provided an apparatus for preparing a unit cell
which includes: a center electrode reel from which a center
electrode sheet, which is to be a plurality of center
electrodes, is unwound; separator reels from which separator
sheets to be stacked with the center electrodes are unwound;
a laminator for laminating a stack which is formed by
stacking the plurality of center electrodes with the
separator sheets while the plurality of center electrodes are
spaced apart from each other and disposed in a row in a
longitudinal direction of the separator sheets; a first
nozzle for applying an adhesive to an upper surface of the
separator sheet disposed on an uppermost layer of the stack;
and an upper electrode reel from which an upper electrode
sheet, which is to be a plurality of upper electrodes to be
stacked on an upper surface of the stack to which the
adhesive has been applied, is unwound.
[0012] Also, the apparatus for preparing a unit cell may
further include a first vision sensor disposed above the
center electrode to photograph the center electrode before
the center electrodes are stacked with the separator sheets.
[0013] Furthermore, the apparatus for preparing a unit cell
may further include a second vision sensor disposed above the
upper electrode to photograph the upper electrode before the
5
upper electrode is stacked with the stack.
[0014] Also, the laminator may include a heating roller for
applying heat and pressure to the stack while rotating.
[0015] Furthermore, the laminator may further include a
heater for applying heat and pressure to an entire surface of
the stack.
[0016] Also, the separator reels may include an upper
separator reel from which an upper separator sheet to be
stacked on an upper surface of the center electrode is
unwound; and a lower separator reel from which a lower
separator sheet to be stacked on a lower surface of the
center electrode is unwound.
[0017] Furthermore, the apparatus for preparing a unit cell
may further include a lower electrode reel from which a lower
electrode sheet, which is to be a plurality of lower
electrodes to be stacked on a lower surface of the stack, is
unwound.
[0018] Also, the apparatus for preparing a unit cell may
further include a second nozzle for applying an adhesive to
an upper surface of the lower electrode.
[0019] Furthermore, the apparatus for preparing a unit cell
may further include a third vision sensor disposed above the
lower electrode to photograph the lower electrode before the
lower electrode is stacked with the stack.
[0020] Also, the apparatus for preparing a unit cell may
further include nip rollers which apply pressure to the upper
electrode and the stack while rotating when the upper
electrode is stacked with the stack.
[0021] Furthermore, the first nozzle may be provided in
plurality spaced apart from each other in a width direction
6
of the separator sheets.
[0022] Also, at least one of spraying cycle, spraying area,
and spraying amount of the adhesive may be different from
each other with respect to the plurality of first nozzles.
[0023] Furthermore, the upper separator sheet may include a
first base material layer; and a first coating layer coated
on an upper surface of the first base material layer and
bonded to the upper electrode while the adhesive is applied.
The lower separator sheet may include a second base material
layer; and a second coating layer coated on an upper surface
of the second base material layer and bonded to the center
electrode. A binder content of the first coating layer may
be lower than a binder content of the second coating layer.
[0024] Also, the binder content of the first coating layer
may be in a range of 2 wt% to 3 wt%.
[0025] Furthermore, the second coating layer may have the
binder content of 10 wt% to 20 wt% and may be a safety
reinforced separator (SRS) coating layer.
[0026] Also, the upper separator sheet may include a first
base material layer bonded to the upper electrode while the
adhesive is applied. The lower separator sheet may include a
second base material layer; and a coating layer coated on an
upper surface of the second base material layer and bonded to
the center electrode.
[0027] According to another aspect of the present invention,
there is provided a method of preparing a unit cell which
includes: cutting a center electrode sheet unwound from a
center electrode reel to form a plurality of center
electrodes; forming a stack by stacking the plurality of
center electrodes on separator sheets unwound from separator
7
reels while the plurality of center electrodes are spaced
apart from each other and disposed in a row in a longitudinal
direction of the separator sheets; laminating the stack with
a laminator; applying an adhesive by a first nozzle on an
upper surface of the separator sheet disposed on an uppermost
layer of the stack; cutting an upper electrode sheet unwound
from an upper electrode reel to form a plurality of upper
electrodes; and stacking the plurality of upper electrodes on
an upper surface of the stack to which the adhesive has been
applied.
[0028] Also, the method may further include photographing
the center electrode with a first vision sensor disposed
above the center electrode, before the forming of the stack.
[0029] Furthermore, the method may further include
photographing the upper electrode with a second vision sensor
disposed above the upper electrode, before the stacking of
the upper electrode.
[0030] Also, the stacking of the upper electrode may stack
the plurality of upper electrodes on the upper surface of the
stack while the plurality of upper electrodes are spaced
apart from each other and disposed in a raw in a length
direction of the separator sheet.
[0031] Furthermore, the laminating may include applying heat
and pressure to the stack by a heating roller while the
heating roller rotates.
[0032] Also, the laminating may further include applying
heat and pressure to an entire surface of the stack by a
heater, before the heating roller applies the heat and the
pressure.
[0033] Furthermore, when the forming of the upper electrode
8
is performed, forming a plurality of lower electrodes by
cutting a lower electrode sheet unwound from a lower
electrode reel may also be performed, and, when the stacking
of the upper electrode is performed, stacking the plurality
of lower electrodes on a lower surface of the stack may also
be performed.
[0034] Also, when the applying of the adhesive on the upper
surface of the stack is performed, applying an adhesive on an
upper surface of the lower electrode by a second nozzle may
also be performed.
[0035] Furthermore, in the applying of the adhesive on the
upper surface of the stack, a region to which the adhesive is
applied may correspond to at least a portion of an edge of
the upper electrode.
[0036] Also, in the applying of the adhesive on the upper
surface of the stack, a region to which the adhesive is
applied may include regions corresponding to four vertices of
the upper electrode.
[0037] Furthermore, in the applying of the adhesive on the
upper surface of the stack, a region to which the adhesive is
applied may form a plurality of rows parallel to a movement
direction of the stack.
[0038] Also, a spacing between the regions to which the
adhesive is applied in one row may be smaller than a spacing
between the regions to which the adhesive is applied in
another row.
[0039] Furthermore, a size of each region to which the
adhesive is applied in one row may be smaller than a size of
each region to which the adhesive is applied in another row.
[0040] Also, the one row may be located outer side than the
9
another row with respect to a width direction of the stack.
[0041] Furthermore, the one row may correspond to an
electrode tab of the upper electrode.
[0042] Other specific details of the present invention are
included in the detailed description and drawings.
ADVANTAGEOUS EFFECTS
[0043] According to the embodiments of the present invention,
at least the following effects may be achieved.
[0044] Since a laminating process is first performed on a
stack, which is formed by stacking a center electrode and a
separator, and an upper electrode is then stacked, heat is
transferred to the inside of the stack during the laminating
process, and thus, a problem of reducing adhesion between the
electrode and the separator may be prevented.
[0045] Also, since the upper electrode is stacked after an
adhesive is applied on an upper surface of the stack
subjected to the laminating process, a displacement in
position of the upper electrode may be prevented.
[0046] The effects according to the present invention are
not limited to the contents as exemplified above, but more
various effects are included in the specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] FIG. 1 is a flowchart of a method of preparing a unit
cell according to an embodiment of the present invention;
[0048] FIG. 2 is a schematic view of an apparatus for
preparing a unit cell according to an embodiment of the
present invention;
[0049] FIG. 3 is a schematic side view illustrating in
detail the apparatus for preparing a unit cell according to
the embodiment of the present invention;
10
[0050] FIG. 4 is a cross-sectional view of an upper
separator sheet according to an embodiment of the present
invention;
[0051] FIG. 5 is a cross-sectional view of a lower separator
sheet according to an embodiment of the present invention;
[0052] FIG. 6 is a view illustrating a nozzle according to
an embodiment of the present invention;
[0053] FIG. 7 is views illustrating adhesive regions between
an upper electrode and an upper separator sheet of FIG. 3 by
an adhesive;
[0054] FIG. 8 is a schematic view of an apparatus for
preparing a unit cell according to another embodiment of the
present invention;
[0055] FIG. 9 is a schematic side view illustrating in
detail the apparatus for preparing a unit cell according to
the another embodiment of the present invention;
[0056] FIG. 10 is a view illustrating a nozzle according to
another embodiment of the present invention;
[0057] FIG. 11 is a view illustrating adhesive regions
between an upper electrode and an upper separator sheet of
FIG. 9 by an adhesive;
[0058] FIG. 12 is a schematic view of an apparatus for
preparing a unit cell according to another embodiment of the
present invention; and
[0059] FIG. 13 is a schematic side view illustrating in
detail the apparatus for preparing a unit cell according to
the another embodiment of the present invention.
MODE FOR CARRYING OUT THE INVENTION
[0060] Advantages and features of the present invention, and
implementation methods thereof will be clarified through
11
following embodiments described with reference to the
accompanying drawings. The present invention may, however,
be embodied in different forms and should not be construed as
limited to the embodiments set forth herein. Rather, these
embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
present invention to those skilled in the art. Further, the
present invention is only defined by scopes of claims. Like
reference numerals refer to like elements throughout.
[0061] Unless defined otherwise, all terms (including
technical and scientific terms) used herein may be intended
to have meanings understood by those skilled in the art. In
addition, terms defined in general dictionaries should not be
interpreted abnormally or exaggeratedly, unless clearly
specifically defined.
[0062] The terminology used herein is for the purpose of
describing particular example embodiments only and is not
intended to be limiting of the present invention. In the
specification, the terms of a singular form may include
plural forms unless referred to the contrary. It will be
further understood that the terms "comprises" and/or
"comprising" when used in this specification, specify the
presence of stated components, but do not preclude the
presence or addition of one or more other components.
[0063] Hereinafter, preferred embodiments of the present
invention will be described in detail with reference to the
accompanying drawings.
[0064] FIG. 1 is a flowchart of a method of preparing a unit
cell according to an embodiment of the present invention.
[0065] According to an embodiment of the present invention,
12
since a laminating process is first performed on a stack 20,
which is formed by stacking a center electrode 1112 and a
separator 12, and an upper electrode 1122 is then stacked,
heat is transferred to the inside of the stack 20 during the
laminating process, and thus, a problem of reducing adhesion
between an electrode 11 and the separator 12 may be prevented.
Also, since the upper electrode 1122 is stacked after an
adhesive is applied on an upper surface of the stack 20
subjected to the laminating process, a displacement in
position of the upper electrode 1122 may be prevented.
[0066] For this purpose, the method of preparing a unit cell
according to the embodiment of the present invention includes
the steps of: cutting a center electrode sheet 1111 unwound
from a center electrode reel 111 to form a plurality of
center electrodes 1112 (S101); forming a stack 20 by stacking
the plurality of center electrodes 1112 on separator sheets
1211 and 1221 unwound from separator reels 121 and 122 while
the plurality of center electrodes 1112 are spaced apart from
each other and disposed in a row in a longitudinal direction
of the separator sheets 1211 and 1221 (S102); laminating the
stack 20 with a laminator (S103); applying an adhesive by a
first nozzle 14 on an upper surface of the separator sheet
1211 and 1221 disposed on an uppermost layer of the stack 20
(S104); cutting an upper electrode sheet 1121 unwound from an
upper electrode reel 112 to form a plurality of upper
electrodes 1122; and stacking the plurality of upper
electrodes 1122 on an upper surface of the stack 20 to which
the adhesive has been applied (S105).
[0067] Hereinafter, each step illustrated in the flowchart
of FIG. 1 will be described in detail with reference to FIGS.
13
2 and 3.
[0068] FIG. 2 is a schematic view of an apparatus 1 for
preparing a unit cell according to an embodiment of the
present invention.
[0069] As illustrated in FIG. 2, the apparatus 1 for
preparing a unit cell according to the embodiment of the
present invention may include a center electrode reel 111
from which a center electrode sheet 1111, which is to be a
plurality of center electrodes 1112, is unwound; separator
reels 121 and 122 from which separator sheets 1211 and 1221
to be stacked with the center electrode 1112 are unwound; a
laminator for laminating a stack 20 which is formed by
stacking the plurality of center electrodes 1112 with the
separator sheets 1211 and 1221 while the plurality of center
electrodes 1112 are spaced apart from each other and disposed
in a row in a longitudinal direction of the separator sheets
1211 and 1221; a first nozzle 14 for applying an adhesive to
an upper surface of the separator sheet 1211 and 1221
disposed on an uppermost layer of the laminated stack 20; and
an upper electrode reel 112 from which an upper electrode
sheet 1121, which is to be a plurality of upper electrodes
1122 to be stacked on an upper surface of the stack 20 to
which the adhesive has been applied, is unwound. In addition,
the separator reels 121 and 122 may include an upper
separator reel 121 from which an upper separator sheet 1211
to be stacked on an upper surface of the center electrode
1112 is unwound; and a lower separator reel 122 from which a
lower separator sheet 1221 to be stacked on a lower surface
of the center electrode 1112 is unwound.
[0070] The center electrode reel 111 is a reel on which the
14
center electrode sheet 1111 is wound, and the center
electrode sheet 1111 is unwound from the center electrode
reel 111. Then, the center electrode sheet 1111 is cut to
form the center electrode 1112. The electrode sheets 1111
and 1121 may be prepared by coating a slurry of an electrode
active material, a conductive agent, and a binder on an
electrode collector, drying, and then pressing the coated
electrode collector.
[0071] The upper separator reel 121 and the lower separator
reel 122 are reels on which the separator sheets 1211 and
1221 are wound. In addition, the upper separator sheet 1211
unwound from the upper separator reel 121 is stacked on the
upper surface of the central electrode 1112 which is formed
by cutting the center electrode sheet 1111, and the lower
separator sheet 1221 unwound from the lower separator reel
122 is stacked on the lower surface of the center electrode
1112. As a result, the stack 20 is formed in which the lower
separator sheet 1221, the center electrode 1112, and the
upper separator sheet 1211 are sequentially stacked. The
stack 20 is formed by stacking the plurality of center
electrodes 1112 on the separator sheets 1211 and 1221 while
the plurality of center electrodes 1112 are spaced apart from
each other and disposed in a row in a longitudinal direction
of the separator sheets 1211 and 1221.
[0072] The laminator laminates an entire surface of the
stack 20 which is formed by stacking the center electrode
1112 and the separator 12. The expression “laminating”
refers to bonding the center electrode 1112 and the separator
12 by applying heat and pressure to the stack 20. As
illustrated in FIG. 2, the laminator may include a heater 15
15
for applying heat and pressure to the entire surface of the
stack 20 and a heating roller 16 for applying pressure to the
stack 20 while rotating.
[0073] The heater 15 is composed of an upper heater 151 and
a lower heater 152, wherein the upper heater 151 and the
lower heater 152 each may apply heat and pressure to the
entire surface of upper and lower surfaces of the stack 20.
In the heater 15, surfaces in contact with the stack 20, that
is, a lower surface of the upper heater 151 and an upper
surface of the lower heater 152 may be formed substantially
flat. Thus, heat and pressure may be uniformly applied to
the entire surface of the stack 20.
[0074] After the heater 15 applies heat and pressure to the
stack 20, the heating roller 16 may apply heat and pressure
to the stack 20 while rotating. In general, the heating
roller 16, which applies pressure while rotating, applies a
higher pressure than the heater 15 that simply applies
pressure with a flat surface. Thus, after the heater 15
applies heat and pressure to the stack 20, the heating roller
16 applies heat and pressure greater than those of the heater
15 to the stack 20 so that the heat and pressure applied to
the stack (20) may be increased step by step. That is, the
stack 20 may be laminated more strongly while preventing the
inside of the stack 20 from being damaged due to rapid
changes in temperature and pressure.
[0075] The nozzle 14 applies an adhesive to the upper
surface of the laminated stack 20. In this case, since the
upper separator sheet 1211 is stacked on the uppermost layer
of the stack 20, the adhesive is applied to an upper surface
of the upper separator sheet 1211.
16
[0076] The nozzles 14 may be provided in plurality spaced
apart from each other along a width direction of the
separator sheets 1211 and 1221. Accordingly, the adhesive
may be simultaneously applied to different regions of the
upper surface of the upper separator sheet 1211. Thus, an
adhesive application operation by the nozzle 14 may be
quickly performed.
[0077] For example, some of the plurality of nozzles 14 may
apply the adhesive near both edges in a width direction of
the upper separator sheet 1211, and the others thereof may
apply the adhesive near a center of the upper separator sheet
1211.
[0078] A spraying speed, spraying amount, or spraying area
of the adhesive sprayed from the plurality of nozzles 14 may
be individually adjusted. With respect to the plurality of
first nozzles 14, at least one of spraying cycle, spraying
area, and spraying amount of the adhesive may be adjusted to
be different from each another.
[0079] It is desirable that the adhesive is uniformly
applied to the upper surface of the stack 20. However, if
the adhesive is applied to an entire surface of the upper
surface of the stack 20, an amount of the adhesive applied
may be excessively large. Accordingly, the adhesive may flow
to the outside of the stack 20 to contaminate other parts,
and a function of generating power may not be smooth when a
secondary battery is prepared. Thus, the adhesive may be
applied to the upper surface of the stack 20 by a spot
application method of applying the adhesive in the form of a
dot or a line application method of applying the adhesive in
the form of a line.
17
[0080] In contrast, if the amount of the adhesive applied is
excessively small, the upper electrode 1122 is still not
fixed to the stack 20 while the stack 20 is moved, and the
upper electrode 1122 may be out of position. Thus, it is
desirable that a spacing between regions to which the
adhesive is applied is not excessively large.
[0081] The adhesive must maintain adhesiveness even if the
separator 12 is impregnated with an electrolyte solution.
Thus, it is desirable that the adhesive has a property of
corrosion resistance that is not modified by chemical causes.
Such an adhesive is a hot melt adhesive, wherein the adhesive
may include a modified olefin-based thermoplastic resin.
[0082] The upper electrode reel 112 is a reel on which the
upper electrode sheet 1121 is wound, and the upper electrode
sheet 1121 is unwound from the upper electrode reel 112. The
upper electrode sheet 1121 is cut to form a plurality of
upper electrodes 1122, and the plurality of upper electrodes
1122 are stacked on the upper surface of the stack 20 to
which the adhesive is applied. In this case, the plurality
of upper electrodes 1122 may be stacked on the upper surface
of the stack 20 while being spaced apart from each other and
disposed in a row in the longitudinal direction of the
separator sheets 1211 and 1221. Since the upper electrode
1122 and the center electrode 1112 have different sizes,
spaced-apart spacings may be different. However, it is
desirable that both the upper electrode 1122 and the center
electrode 1112 are aligned and disposed so that their centers
coincide.
[0083] The method of preparing a unit cell according to the
embodiment of the present invention may be performed as
18
follows, using the apparatus 1 for preparing a unit cell as
described above.
[0084] As illustrated in FIG. 2, when the center electrode
sheet 1111 is first unwound from the center electrode reel
111, a first cutter 131 cuts the center electrode sheet 1111
(S101). Then, the plurality of center electrodes 1112 are
formed. The upper separator sheet 1211 is unwound from the
upper separator reel 121 and stacked on the upper surface of
the center electrode 1112, and the lower separator sheet 1221
is unwound from the lower separator reel 122 and stacked on
the lower surface of the center electrode 1112 to form the
stack 20 (S102). In this case, in order for the lower
separator sheet 1221, the center electrode 1112, and the
upper separator sheet 1211 to be easily and strongly adhered
to one another, first nip rolls 181 may be disposed on both
sides of the stack 20, respectively, and may apply pressure
to the stack 20 while rotating.
[0085] After forming the stack 20, the laminator laminates
the stack 20 (S103). As described above, the laminator
includes the heater 15 and the heating roller 16, and, when
laminating, after the heater 15 applies heat and pressure to
the entire surface of the stack 20, the heating roller 16 may
apply heat and pressure to the stack 20 while rotating.
[0086] When the laminating process is completed, a second
cutter 132 cuts the stack 20 at a predetermined interval, and
the nozzle 14 applies an adhesive to the upper surface of the
cut stack 20 (S104). When the upper electrode sheet 1121 is
unwound from the upper electrode reel 112, a third cutter 133
cuts the upper electrode sheet 1121 to form the upper
electrode 1122. In addition, the upper electrode 1122 is
19
stacked on the upper surface of the stack 20 to which the
adhesive has been applied (S105). As a result, a unit cell 2
is prepared in which the lower separator sheet 1221, the
center electrode 1112, the upper separator sheet 1211, and
the upper electrode 1122 are sequentially stacked. In this
case, in order for the upper electrode 1122 and the stack 20
to be easily and strongly adhered to each other, second nip
rolls 182 may be disposed on both sides of the upper
electrode 1122 and the stack 20, respectively, and may apply
pressure to the upper electrode 1122 and the stack 20 while
rotating.
[0087] FIG. 3 is a schematic side view illustrating in
detail the apparatus 1 for preparing a unit cell according to
the embodiment of the present invention.
[0088] As illustrated in FIG. 3, the apparatus 1 for
preparing a unit cell according to the embodiment of the
present invention may further include a first vision sensor
171 disposed above the center electrode 1112 to photograph
the center electrode 1112 before the center electrode 1112 is
stacked with the separator sheets 1211 and 1221; and a second
vision sensor 172 disposed above the upper electrode 1122 to
photograph the upper electrode 1122 before the upper
electrode 1122 is stacked with the stack 20.
[0089] The first and second vision sensors 171 and 172
acquire an image by photographing a specific region and
receiving an image signal for the specific region. For this
purpose, a vision sensor generally includes an imaging device
such as a charge coupled device (CCD) or a complementary
metal-oxide semiconductor (CMOS). Particularly, the first
and second vision sensors 171 and 172 according to an
20
embodiment of the present invention may acquire images by
photographing the center electrode 1112 and the upper
electrode 1122, respectively.
[0090] Although not shown in the drawings, the apparatus 1
for preparing a unit cell may further include a controller
(not shown) which may determine whether the center electrode
1112 and the upper electrode 1122 are defective or not
through the images of the center electrode 1112 and the upper
electrode 1122. The controller may determine whether sizes
and shapes of the center electrode 1112 and the upper
electrode 1122 are defective or damaged or not by comparing
the obtained images with previously stored images of the
center electrode 1112 and the upper electrode 1122 of a good
product.
[0091] When these first and second vision sensors 171 and
172 are used, the first vision sensor 171 disposed above the
center electrode 1112 may photograph the center electrode
1112 before the center electrode 1112 and the separator
sheets 1211 and 1221 are stacked to form the stack 20, and
the second vision sensor 172 disposed above the upper
electrode 1122 may photograph the upper electrode 1122 before
stacking the upper electrode 1122 on the stack 20. That is,
before the electrode 11 is stacked with the separator 12,
whether only the electrode 11 is defective or not may be
confirmed in advance.
[0092] FIG. 4 is a cross-sectional view of an upper
separator sheet according to an embodiment of the present
invention, and FIG. 5 is a cross-sectional view of a lower
separator sheet according to an embodiment of the present
invention.
21
[0093] The separator sheets 1211 and 1221 may include base
material layers 1211a and 1221a and coating layers 1211b and
1221b, respectively.
[0094] The base material layers 1211a and 1221a are porous
base materials, wherein the base material layers 1211a and
1221a may include a polyethylene or polypropylene resin.
[0095] The coating layers 1211b and 1221b may be formed by
respectively coating the base material layers 1211a and 1221a
with a ceramic slurry including a filler and a binder. The
coating layers 1211b and 1221b may be ceramic coating layers.
For example, the filler may include alumina (aluminum oxide),
and the binder may include polyvinylidene fluoride (PVDF).
[0096] Specifically, the upper separator sheet 1211 may
include the first base material layer 1211a and the first
coating layer 1211b coated on an upper surface of the first
base material layer 1211a, and the lower separator sheet 1221
may include the second base material layer 1221a and the
second coating layer 1221b coated on an upper surface of the
second base material layer 1221a.
[0097] Thus, the center electrode 1112 may be bonded to an
upper surface of the second coating layer 1221b by the
laminating process described above. The second coating layer
1221b may be a safety reinforced separator (SRS) coating
layer. For example, an amount of the binder in the second
coating layer 1221b may be in a range of 10 wt% to 20 wt%.
[0098] Also, the nozzle 14 may apply an adhesive to an upper
surface of the first coating layer 1211b, and the upper
electrode 1122 may be bonded to the upper surface of the
first coating layer 1211b by the adhesive. Thus, an amount
of the binder in the first coating layer 1211b may be lower
22
than the amount of the binder in the second coating layer
1221b. Specifically, the amount of the binder in the first
coating layer 1211b may be less than half of the amount of
the binder in the second coating layer 1221b. As a result, a
thickness t1 of the first coating layer 1211b may be smaller
than a thickness t2 of the second coating layer 1221b.
[0099] That is, since the amount of the binder in the first
coating layer 1211b is decreased, a thickness of the upper
separator sheet 1211 may be reduced and energy density of the
unit cell 2 may be improved.
[00100] Specifically, the amount of the binder in the first
coating layer 1211b may be in a range of 2 wt% to 3 wt%.
Accordingly, bonding between the first coating layer 1211b
and the first base material layer 1211a may be maintained
while maintaining the thickness of the first coating layer
1211b as thin as possible. If the amount of the binder in
the first coating layer 1211b is less than 2 wt%, there is a
problem that the bonding between the first coating layer
1211b and the first base material layer 1211a is not
maintained. Also, if the amount of the binder in the first
coating layer 1211b is greater than 3 wt%, the thickness of
the first coating layer 1211b may be increased.
[00101] A configuration, in which the upper separator sheet
1211 does not include the first coating layer 1211b, is also
possible. In this case, the nozzle 14 may apply an adhesive
to the upper surface of the first base material layer 1211a,
and a lower surface of the upper electrode 1122 may be bonded
to the upper surface of the first base material layer 1211a
by the adhesive.
[00102] Thus, there is an advantage that the thickness of the
23
upper separator sheet 1211 becomes thinner. However,
application of the configuration, in which the upper
separator sheet 1211 does not include the first coating layer
1211b, when the upper electrode 1122 is a positive electrode
is desirable in terms of stability.
[00103] FIG. 6 is a view illustrating a nozzle according to
an embodiment of the present invention.
[00104] The nozzle 14 according to the present embodiment may
spray an adhesive S in the form of a mist by spraying
adhesive particles and compressed air together. Specifically,
the nozzle 14 may include a housing 141 having an inner space,
a tube 142 for supplying the adhesive S to the inside of the
housing 141, and a line 143 for supplying the compressed air
to the inside of the housing 141.
[00105] Also, a spraying portion 141a for spraying the
adhesive S and the compressed air together toward the upper
separator sheet 1211 of the stack 20 may be formed at a lower
end of the housing 141.
[00106] That is, when the adhesive S supplied to the housing
141 through the tube 142 is discharged to the spraying
portion 141a, the compressed air is injected into the housing
141 from the line 143 so that the adhesive S may be
discharged through the spraying portion 141a together with
the compressed air.
[00107] In a process of being discharged with the compressed
air, the adhesive S becomes a mist while the adhesive
particles are split by the compressed air, and, in that state,
the adhesive S may be applied to the upper surface of the
upper separator sheet 1211, more particularly, the first
coating layer 1211b.
24
[00108] Since the adhesive S applied by such a spraying
method may be applied in the form of small particles by a
predetermined amount at a predetermined position, the
adhesive S may be uniformly applied to the upper surface of
the first coating layer 1211b of the upper separator sheet
1211 and may penetrates evenly throughout a region where the
adhesive has been applied, and thus, optimum adhesion may be
provided without wasting the adhesive S.
[00109] However, a configuration of the nozzle 14 is not
limited thereto, and it is, of course, possible to adopt an
inkjet spraying method (see FIG. 10) to be described later.
[00110] FIG. 7 is views illustrating adhesive regions between
the upper separator sheet and the upper electrode of FIG. 3
by the adhesive.
[00111] The upper electrode 1122 may have a rectangular shape
having a relatively short pair of short sides and a
relatively long pair of long sides. The upper electrode 1122
may be stacked on the upper separator sheet 1211 so that the
long side is parallel to the width direction of the upper
separator sheet 1211.
[00112] An adhesive region A1 bonded to each other by the
adhesive may be positioned between the upper electrode 1122
and the upper separator sheet 1211. That is, the adhesive
region A1 may mean a region in which the nozzle 14 applies
the adhesive on the upper surface of the upper separator
sheet 1211.
[00113] As a first example, as illustrated in (a) of FIG. 7,
the adhesive region A1 may extend along a circumference of
the upper electrode 1122. In this case, the adhesive region
A may have a rectangular ring shape, and may surround a non25
adhesive region A2.
[00114] Thus, an edge portion of the lower surface of the
upper electrode 1122 may be adhered to the upper separator
sheet 1211. Also, the adhesive region A may protrude to
correspond to an electrode tab protruding from the upper
electrode 1122.
[00115] As a second example, as illustrated in (b) of FIG. 7,
the adhesive region A1 may extend along both short sides of
the upper electrode 1122. Thus, portions of the lower
surface of the upper electrode 1122 adjacent to the both
short sides may be adhered to the upper separator sheet 1211.
In this case, the non-adhesive region A2 may include regions
adjacent to both long sides of the lower surface of the upper
electrode 1122. Also, the adhesive region A may protrude to
correspond to an electrode tab protruding from the upper
electrode 1122.
[00116] As a third example, as illustrated in (c) of FIG. 7,
the adhesive region A1 may extend along both long sides of
the upper electrode 1122. Thus, portions of the lower
surface of the upper electrode 1122 adjacent to the both long
sides may be adhered to the upper separator sheet 1211. In
this case, the non-adhesive region A2 may include regions
adjacent to both short sides of the lower surface of the
upper electrode 1122.
[00117] As in the first to third examples, in the step of
applying the adhesive to the upper surface of the stack 20, a
region to which the adhesive is applied may correspond to at
least a portion of the edge of the upper electrode 1122.
[00118] As a fourth example, as illustrated in (d) of FIG. 7,
the adhesive region A1 may be located in regions
26
corresponding to four vertices of the upper electrode 1122.
Thus, portions adjacent to the four vertices of the lower
surface of the upper electrode 1122 may be adhered to the
upper separator sheet 1211. In this case, the non-adhesive
region A2 may include a portion of regions adjacent to both
long sides of the lower surface of the upper electrode 1122
and a portion of regions adjacent to both short sides thereof.
[00119] With respect to the first to fourth examples, the
adhesive region A may additionally include a region (not
shown) corresponding to a center of the upper electrode 1122.
As a fifth example, as illustrated in (e) of FIG. 7, the
adhesive region A1 may include a first region extending along
the circumference of the upper electrode 1122 and a second
region extending parallel to the short side or the long side
of the upper electrode 1122 and passing through the center of
the upper electrode 1122 in addition to the first region.
Thus, more robust adhesion than that of the first example is
possible.
[00120] The adhesive region A1 may surround the non-adhesive
region A2. A plurality of non-adhesive regions A2, which are
partitioned from each other by the second region of the
adhesive region A1, may be formed. Also, the adhesive region
A1 may protrude to correspond to an electrode tab protruding
from the upper electrode 1122.
[00121] With respect to the first to fifth examples, an area
of the adhesive region A1 may be smaller than an area of the
non-adhesive region A2. As a sixth example, as illustrated
in (f) of FIG. 7, the adhesive region A1 may have a shape
corresponding to the upper electrode 1122. Thus, the entire
lower surface of the upper electrode 1122 may be adhered to
27
the upper separator sheet 1211. In this case, the nonadhesive
region A2 does not exist.
[00122] As in the first to sixth examples, in the step of
applying the adhesive to the upper surface of the stack 20,
the region to which the adhesive is applied may include
regions corresponding to the four vertices of the upper
electrode 1122.
[00123] FIG. 8 is a schematic view of an apparatus 1a for
preparing a unit cell according to another embodiment of the
present invention, and FIG. 9 is a schematic side view
illustrating in detail the apparatus 1a for preparing a unit
cell according to the another embodiment of the present
invention.
[00124] According to embodiments of the present invention, a
laminating process is first performed on the stack 20, which
is formed by stacking the center electrode 1112 and the
separator 12, and the upper electrode 1122 is then stacked.
As a result, since heat is transferred to the inside of the
stack 20 in the laminating process, a problem of reducing the
adhesion between the electrode 11 and the separator 12 may be
prevented. Thus, there is no need to apply excessive heat
and pressure to the stack 20 in the laminating process.
[00125] Therefore, in the apparatus 1a for preparing a unit
cell according to the another embodiment of the present
invention, as illustrated in FIGS. 8 and 9, the heater 15 is
removed from the laminator, and only the heating roller 16
laminates the stack 20. In general, since the heating roller
16 may apply a higher pressure to the stack 20 than the
heater 15, the heating roller 16 alone may sufficiently
laminate the stack 20.
28
[00126] As described above, since the heater 15 is removed
from the laminator, complication of the apparatus 1a for
preparing a unit cell may be prevented, an overall volume may
be reduced, and costs may be reduced. However, in order to
prevent the inside of the stack 20 from being damaged due to
rapid changes in temperature and pressure, the heating roller
16 must be adjusted so that the heat and pressure applied to
the stack 20 are not excessively large.
[00127] FIG. 10 is a view illustrating a nozzle according to
another embodiment of the present invention.
[00128] The nozzle 14’ according to the present embodiment
may inkjet spray an adhesive S in the form of fine droplets
by a pressure change in a pressure chamber 141a’.
Specifically, the nozzle 14' may include a housing 141’
having the pressure chamber 141a’, a wall 142’ which is
provided on one side of the housing 141’ and moves to cause a
change in volume of the pressure chamber 141a, and a tube
143’ for supplying the adhesive S to the pressure chamber
141a’.
[00129] Also, a discharge port 141b through which the
adhesive S is discharged toward the upper separator sheet
1211 of the stack 20 may be formed at a lower end of the
housing 141’.
[00130] The adhesive S, in a state in which it is filled in
the pressure chamber 141a’, is not discharged through the
discharge port 141b due to viscosity of the adhesive S. In
this state, if the wall 142’ moves in a direction of reducing
the volume of the pressure chamber 141a’, an internal
pressure of the pressure chamber 141a’ increases, and the
adhesive S is discharged to the outside through the discharge
29
port 141b to be applied to the upper surface of the upper
separator sheet 1211. In addition, when the wall 142’ is
restored to its original state, the discharge of the adhesive
S is stopped.

CLAIMS
1. An apparatus for preparing a unit cell, the
apparatus comprising:
a center electrode reel from which a center electrode
sheet, which is to be a plurality of center electrodes, is
unwound;
separator reels from which separator sheets to be
stacked with the center electrodes are unwound;
a laminator for laminating a stack which is formed by
stacking the plurality of center electrodes with the
separator sheets while the plurality of center electrodes are
spaced apart from each other and disposed in a row in a
longitudinal direction of the separator sheets;
a first nozzle for applying an adhesive to an upper
surface of the separator sheet disposed on an uppermost layer
of the laminated stack; and
an upper electrode reel from which an upper electrode
sheet, which is to be a plurality of upper electrodes to be
stacked on an upper surface of the stack to which the
adhesive has been applied, is unwound.
2. The apparatus for preparing a unit cell of claim
1, wherein the separator reels comprise an upper separator
reel from which an upper separator sheet to be stacked on an
upper surface of the center electrode is unwound; and
a lower separator reel from which a lower separator
sheet to be stacked on a lower surface of the center
electrode is unwound.
36
3. The apparatus for preparing a unit cell of claim
1, further comprising a lower electrode reel from which a
lower electrode sheet, which is to be a plurality of lower
electrodes to be stacked on a lower surface of the stack, is
unwound.
4. The apparatus for preparing a unit cell of claim
3, further comprising a second nozzle for applying an
adhesive to an upper surface of the lower electrode.
5. The apparatus for preparing a unit cell of claim
1, further comprising nip rollers which apply pressure to the
upper electrode and the stack while rotating when the upper
electrode is stacked with the stack.
6. The apparatus for preparing a unit cell of claim
1, wherein the first nozzle is provided in plurality spaced
apart from each other in a width direction of the separator
sheets.
7. The apparatus for preparing a unit cell of claim
6, wherein at least one of spraying cycle, spraying area, and
spraying amount of the adhesive is different from each other
with respect to the plurality of first nozzles.
8. The apparatus for preparing a unit cell of claim
2, wherein the upper separator sheet comprises:
a first base material layer; and
a first coating layer coated on an upper surface of the
first base material layer and bonded to the upper electrode
37
while the adhesive is applied, and
the lower separator sheet comprises:
a second base material layer; and
a second coating layer coated on an upper surface of
the second base material layer and bonded to the center
electrode,
wherein a binder content of the first coating layer is
lower than a binder content of the second coating layer.
9. The apparatus for preparing a unit cell of claim
8, wherein the binder content of the first coating layer is
in a range of 2 wt% to 3 wt%.
10. The apparatus for preparing a unit cell of claim
8, wherein the second coating layer has the binder content of
10 wt% to 20 wt% and is a safety reinforced separator (SRS)
coating layer.
11. The apparatus for preparing a unit cell of claim
2, wherein the upper separator sheet comprises:
a first base material layer bonded to the upper
electrode while the adhesive is applied, and
the lower separator sheet comprises:
a second base material layer; and
a coating layer coated on an upper surface of the
second base material layer and bonded to the center electrode.
12. A method of preparing a unit cell, the method
comprising:
cutting a center electrode sheet unwound from a center
38
electrode reel to form a plurality of center electrodes;
forming a stack by stacking the plurality of center
electrodes on separator sheets unwound from separator reels
while the plurality of center electrodes are spaced apart
from each other and disposed in a row in a longitudinal
direction of the separator sheets;
laminating the stack with a laminator;
applying an adhesive by a first nozzle on an upper
surface of the separator sheet disposed on an uppermost layer
of the stack;
cutting an upper electrode sheet unwound from an upper
electrode reel to form a plurality of upper electrodes; and
stacking the plurality of upper electrodes on an upper
surface of the stack to which the adhesive has been applied.
13. The method of claim 12, wherein, in the applying
of the adhesive on the upper surface of the stack, a region
to which the adhesive is applied corresponds to at least a
portion of an edge of the upper electrode.
14. The method of claim 12, wherein, in the applying
of the adhesive on the upper surface of the stack, a region
to which the adhesive is applied comprises regions
corresponding to four vertices of the upper electrode.
15. The method of claim 12, wherein, in the applying
of the adhesive on the upper surface of the stack,
a region to which the adhesive is applied forms a
plurality of rows parallel to a movement direction of the
stack.
39
16. The method of claim 15, wherein a spacing between
the regions to which the adhesive is applied in one row is
smaller than a spacing between the regions to which the
adhesive is applied in another row.
17. The method of claim 15, wherein a size of each
region to which the adhesive is applied in one row is smaller
than a size of each region to which the adhesive is applied
in another row.
18. The method of claim 16 or 17, wherein the one row
is located outer side than the another row with respect to a
width direction of the stack.
19. The method of claim 16 or 17, wherein the one row
corresponds to an electrode tab of the upper electrode.