U.S. patent application number 13/599547 was filed with the patent office on 2012-12-20 for method and apparatus for manufacturing wound electrode assembly for battery.
This patent application is currently assigned to SANYO Electric Co., Ltd.. Invention is credited to Masatomo MISHIMA, Tatsuya NAGARE, Souichirou UENO.
Application Number | 20120318462 13/599547 |
Document ID | / |
Family ID | 42621793 |
Filed Date | 2012-12-20 |
United States Patent
Application |
20120318462 |
Kind Code |
A1 |
NAGARE; Tatsuya ; et
al. |
December 20, 2012 |
METHOD AND APPARATUS FOR MANUFACTURING WOUND ELECTRODE ASSEMBLY FOR
BATTERY
Abstract
The present invention aims to provide a method for bonding
protective tapes to the cut edges of an electrode plate within a
short period to prevent short circuit in an electrode assembly. An
electrode plate cutting & tape bonding process includes (1)
cutting an electrode plate into pieces 100a and 100b, (2) forming a
gap W between edges 106 and 107 of the pieces 100a and 100b, (3)
bonding protective tapes 51 and 52 to both sides of the pieces 100a
and 100b, covering the edges and the gap, and (4) conveying the
pieces 100a and 100b connected together. Next, the tapes 51 and 52
are cut into pieces 51a & 52a and 51b & 52b. Then, the
electrode plate piece 100a with the tape pieces 51a & 52a and
51b & 52b is wound together with a negative electrode plate,
with a separator sandwiched therebetween.
Inventors: |
NAGARE; Tatsuya; (Hyogo,
JP) ; MISHIMA; Masatomo; (Tokushima, JP) ;
UENO; Souichirou; (Tokushima, JP) |
Assignee: |
SANYO Electric Co., Ltd.
Osaka
JP
|
Family ID: |
42621793 |
Appl. No.: |
13/599547 |
Filed: |
August 30, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12710408 |
Feb 23, 2010 |
|
|
|
13599547 |
|
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Current U.S.
Class: |
156/443 |
Current CPC
Class: |
H01M 10/0431 20130101;
Y02E 60/10 20130101; Y10T 156/1077 20150115; H01M 4/139 20130101;
H01M 10/0587 20130101; H01M 4/08 20130101; Y10T 156/1075 20150115;
H01M 4/26 20130101; Y10T 156/1085 20150115 |
Class at
Publication: |
156/443 |
International
Class: |
H01M 4/04 20060101
H01M004/04 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 23, 2009 |
JP |
2009-039390 |
Claims
1. A wound electrode assembly manufacturing apparatus for
manufacturing a wound electrode assembly by pulling out a strip of
electrode plate bit by bit, cutting off an electrode plate piece
having a length of one cell from the electrode plate, and winding
the electrode plate piece, the apparatus comprising: an electrode
plate cutter operable to cut off the electrode plate piece; a gap
forming unit operable to form a gap between cut edges of the
electrode plate piece and the electrode plate; a tape bonding unit
operable to bond protective tapes to both sides of the electrode
plate piece and the electrode plate to cover the gap and the cut
edges; a tape cutter operable to cut the protective tapes at a
position within the gap; and a winding unit operable to wind the
electrode plate piece having the cut protective tapes bonded
thereto.
2. The apparatus of claim 1, wherein the electrode plate cutter,
the gap forming unit and the tape bonding unit are provided in a
first stage, and the tape cutter is provided in a second stage
following the first stage.
3. The apparatus of claim 1, wherein the gap forming unit forms the
gap by pulling the electrode plate piece and the electrode plate
away from each other.
4. The apparatus of claim 3, wherein the electrode plate cutter,
the gap forming unit and the tape bonding unit are provided in a
first stage, and the tape cutter is provided in a second stage
following the first stage.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. Ser.
No. 12/710,408, filed Feb. 23, 2010, and is based upon and claims
the benefit of priority from the prior Japanese Patent Application
No. 2009-039390, filed on Feb. 23, 2009, the entire contents of
which are incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] (1) Field of the Invention
[0003] The present invention relates to a method for manufacturing
electrode assemblies for batteries and an apparatus for
manufacturing wound electrodes, and in particular to a method for
manufacturing wound electrode assemblies by cutting and winding
pieces of an electrode plate pulled out from an electrode plate
roll.
[0004] (2) Description of the Related Art
[0005] As a method for manufacturing wound electrode assemblies for
batteries, it is common to pull out an electrode plate bit by bit
from an electrode plate roll, cut off one-cell-long pieces from the
electrode plate with a cutter, and wind the electrode plate
pieces.
[0006] Here, degradation of the cutter increases the occurrence of
burrs at the cut edges, and increases burrs in size as well. Such
burrs can be a cause of short circuit in a wound electrode assembly
(Japanese Patent Application Publication No. 10-241737).
[0007] In view of this, a conventional method to control burrs is
required to beforehand determine an acceptable level of burrs,
regularly check the burrs by sampling, and change the cutter with a
new one when the acceptable level is reached.
[0008] Also, as disclosed in Japanese Patent Application
Publication No. 2001-85066, there is a well-known technique to
prevent short circuit in an electrode assembly even if burrs occur
at the cut edge. According to this method, protective tapes are
bonded to the cut edges so as to sandwich them and cover the both
sides of the electrode plate pieces.
SUMMARY OF THE INVENTION
[0009] However, since each one-cell-long electrode plate piece has
two cut edges namely the downstream-side edge and the upstream-side
edge, two processing steps are required to bond protective tapes to
the downstream-side and upstream-side edges. This takes a
considerable time. As the time required for these tape bonding
steps increases, the takt time (i.e. the time interval between
winding up of a one-cell-long piece and winding up of the next
one-cell-long piece) of the winding process increases as well. This
can be a cause of degradation of the productive efficiency.
[0010] Here, it is possible to bond protective tapes to a position
to be cut, before cutting an electrode plate, and cut the
protective tapes and the electrode plate together. This requires
only a single step to bond the protective tapes per one-cell-long
electrode plate piece, and reduces the time for bonding the tapes.
However, if a burr that is larger than the thickness of the
protective tapes occurs in the cutting of the electrode plate, the
protective tapes can not cover the whole burr. In such cases, the
protective tapes do not have a sufficient effect of preventing the
occurrence of short circuit in the electrode assembly.
[0011] The present invention is made in view of the above problem.
An object of the present invention is to provide a method for
achieving a sufficient effect of preventing the occurrence of short
circuit in an electrode assembly by bonding protective tapes to cut
edges of an electrode plate, without taking a considerable time for
the bonding the protective tapes.
[0012] To fulfill this object, the present invention provides a
method for manufacturing a wound electrode assembly, comprising: an
electrode plate cutting step of cutting off an electrode plate
piece having a length of one cell from a strip of electrode plate;
a gap forming step of forming a gap between cut edges of the
electrode plate piece and the electrode plate; a tape bonding step
of bonding protective tapes to both sides of the electrode plate
piece and the electrode plate to cover the gap and the cut edges; a
tape cutting step of cutting the protective tapes at a position
within the gap; and a winding step of winding the electrode plate
piece having the cut protective tapes bonded thereto. Here, the
"protective tape" means a tape for covering the surface of the
electrode plate.
[0013] With the stated method for manufacturing a wound electrode
assembly pertaining to the present invention, a strip of electrode
plate is cut in the electrode plate cutting step, into electrode
plate pieces each having a length of one cell.
[0014] Then, in the gap forming step and the tape bonding step, the
cut edges of each electrode plate piece are covered with protective
tapes, which are bonded to both sides of the electrode plate piece,
and thus adjacent electrode plate pieces are connected together by
protective tapes. Also, as protective tapes are bonded to the cut
edges after the cutting of the electrode plate, the cut edges are
covered with protective tapes in a favorable manner.
[0015] After that, the protective tapes are cut in the tape cutting
step, at a position within the gap between the adjacent electrode
plate pieces, and the electrode plate pieces are separated. Even
after the separation, the cut edges are covered with the protective
tapes bonded to both sides of the electrode plate pieces. Each of
the electrode plate pieces with the protective tapes is wound up in
the winding step, and thus a wound electrode assembly is
manufactured. In an electrode assembly thus manufactured, the edges
of the electrode plate piece are covered with the protective tapes
which sandwich the edges. The tapes therefore have an effect of
preventing the occurrence of short circuit in an electrode assembly
even if burrs that are larger than the thickness of the protective
tapes have occurred at the cut edges.
[0016] Also, according to the stated method for manufacturing a
wound electrode assembly, protective tapes are bonded in the tape
bonding step to both sides of the electrode plate piece and the
electrode plate, to cover the gap and the cut edges. Thus,
protective tapes are bonded to both cut edges by a single
operation. That is, only a single operation is required to bond
protective tapes to a one-cell-long electrode plate piece, which
reduces the time for bonding the tapes.
[0017] As a result, the method pertaining to the present invention
prevents the increase in takt time in the winding process which
might be caused due to the time required for the bonding of the
protective tapes.
[0018] Another aspect of the present invention is a wound electrode
assembly manufacturing apparatus for manufacturing a wound
electrode assembly by pulling out a strip of electrode plate bit by
bit, cutting off an electrode plate piece having a length of one
cell from the electrode plate, and winding the electrode plate
piece, the apparatus comprising: an electrode plate cutter operable
to cut off the electrode plate piece;
[0019] a gap forming unit operable to form a gap between cut edges
of the electrode plate piece and the electrode plate; a tape
bonding unit operable to bond protective tapes to both sides of the
electrode plate piece and the electrode plate to cover the gap and
the cut edges; a tape cutter operable to cut the protective tapes
at a position within the gap; and a winding unit operable to wind
the electrode plate piece having the cut protective tapes bonded
thereto. This apparatus for manufacturing wound electrode assembly
achieves the same effect as the manufacturing method described
above.
[0020] As explained above, the method and the apparatus pertaining
to the present invention realize manufacturing of a wound electrode
assembly that does not easily cause short circuit, without
degrading the productive efficiency.
[0021] In the above-described method and apparatus for
manufacturing the wound electrode assembly, the electrode plate may
be pulled out bit by bit to a first stage in which the electrode
plate cutting step, the gap forming step and the tape bonding step
are performed, and the electrode plate piece with the protective
tapes may be conveyed from the first stage to a second stage in
which the tape cutting step is performed. With this structure, the
processes can be performed in parallel in the first stage and the
second stage.
[0022] This structure further reduces the total time required for
the electrode plate cutting, the gap forming, the tape bonding and
the tape cutting, and more efficiently prevents the increase in
takt time in the winding process.
[0023] Moreover, the second stage immediately before the electrode
plate winding process includes only the protective tape cutting,
and it is unnecessary to perform the electrode plate cutting in
this stage. This prevents powder dust and small fragments,
generated in the electrode plate cutting, from being mixed into the
electrode assembly in the electrode plate winding process.
[0024] The present invention realizes the manufacture of a wound
electrode assembly that does not easily cause short circuit,
without degrading the productive efficiency. Thus, the present
invention is suitable for the manufacture of wound electrode
assemblies for various kinds of batteries such as nonaqueous
electrolyte batteries.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] These and the other objects, advantages and features of the
invention will become apparent from the following description
thereof taken in conjunction with the accompanying drawings which
illustrate a specific embodiment of the invention.
[0026] In the drawings:
[0027] FIG. 1 is a process chart showing manufacturing processes
for an electrode assembly pertaining to an embodiment;
[0028] FIG. 2 shows the structure of an electrode plate 100 with
tabs;
[0029] FIGS. 3A to 3D illustrate an electrode plate cutting &
tape bonding process;
[0030] FIG. 4 illustrates a control mechanism for stopping cutting
line A at a cutting position B;
[0031] FIGS. 5A and 5B each show a cross section of a part of an
electrode plate piece to which protective tapes are bonded;
[0032] FIGS. 6A and 6B illustrate a process for cutting protective
tapes;
[0033] FIG. 7 shows that protective tapes are cut and an electrode
plate piece 100a and an electrode plate piece 100b are separated
from each other;
[0034] FIG. 8 shows a wound electrode assembly manufactured by an
electrode plate winding process; and
[0035] FIGS. 9A to 9C show example sizes of a part of an electrode
plate piece to which protective tapes are bonded.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0036] FIG. 1 is a process chart showing manufacturing processes
for an electrode assembly pertaining to an embodiment of the
present invention.
[0037] As FIG. 1 shows, the manufacturing processes for an
electrode assembly include an electrode plate roll manufacturing
process, a tab attaching process, an electrode plate cutting &
tape bonding process, a protective tape cutting process, and an
electrode plate winding process.
[0038] An electrode plate roll manufactured through the electrode
plate roll manufacturing process is set up in an electrode assembly
winding apparatus.
[0039] The electrode assembly winding apparatus includes a stage
for the tab attaching process, a stage for the electrode plate
cutting & tape bonding process, a stage for the protective tape
cutting process, and a stage for the electrode plate winding
process.
[0040] The electrode plate pulled out from the electrode plate roll
passes through the stages (i.e. stations) in the electrode assembly
winding apparatus one by one, and each of the processes are
performed in the corresponding stage. Specifically, while a portion
of the electrode plate pulled out beforehand in the electrode
assembly winding apparatus is going through the electrode plate
winding process, the subsequent portion of the electrode plate
piece goes through the protective tape cutting process, and another
portion of the electrode plate, following the subsequent electrode
plate, goes through the electrode plate cutting & tape bonding
process and the tab attaching process, respectively in the
corresponding stages.
[0041] The following explains each of the processes, based on an
example case of manufacturing an electrode assembly for a
nonaqueous electrolyte battery and bonding protective tapes to the
positive electrode plate of the electrode assembly.
1. Electrode Plate Roll Manufacturing Process
[0042] A positive-mixture slurry is firstly manufactured by mixing
lithium cobalt oxide as a positive-electrode active material, a
carbon powder as an electrical conducting material, polyvinylidene
fluoride as a binding agent, and N-methylpyrrolidone.
[0043] The slurry is applied on both sides of an aluminum foil
(having the thickness of 15 .mu.m, for example) pulled out from an
aluminum foil roll. Here, the slurry is not applied on cutting
areas 102 near cutting lines A, and tab areas 103 to each of which
a collector tab is to be attached (See FIG. 2).
[0044] The applied slurry is dried with a dryer and pressed with a
roller, and thus a positive-mixture layer 104 is formed. These
steps produce a positive electrode plate, which is an aluminum foil
as a core material, having the positive-mixture layer 104 formed
thereon.
[0045] The electrode plate thus manufactured is cut with a slitter
into strips each having a predetermined width. Also, each of the
strips is wound up to be in the form of a roll. Thus, an electrode
roll in the roll shape is manufactured.
2. Tab Attaching Process
[0046] The electrode roll is set up in the electrode assembly
winding apparatus, and a tab 105 is welded to each of the tab areas
103 of the electrode plate pulled out from the electrode roll.
[0047] FIG. 2 shows an electrode plate 100 pulled out from the
electrode roll, to which tabs 105 have been attached.
[0048] The electrode plate 100 is conveyed to the subsequent stage
for the electrode plate cutting & tape bonding process.
3. Electrode Plate Cutting & Tape Bonding Process
[0049] FIGS. 3A to 3D illustrate the electrode plate cutting &
tape bonding process. As shown in this drawing, the electrode plate
cutting & tape bonding process includes the steps of electrode
plate cutting (FIG. 3A), pitch widening (FIG. 3B), tape bonding
(FIG. 3C) and electrode plate conveying (FIG. 3D), which are to be
performed in the stated order.
[0050] For performing these steps, a pair of rollers 10a & 10b
and a roller 11, which are for conveying the electrode plate 100,
are provided downstream (i.e. the left side on FIGS. 3A to 3D) and
upstream (i.e. the right side on FIGS. 3A to 3D), respectively.
[0051] The electrode assembly winding apparatus is also provided
with a pair of cutters 20a & 20b for cutting the electrode
plate 100, two pairs of chucks 21a & 21b and 22a & 22b for
grasping the electrode plate 100, and a pair of tape bonding jigs
23 & 24 for bonding protective tapes to the electrode plate
100.
[0052] The cutters 20a & 20b are arranged at a cutting position
B between the roller 11 and the rollers 10a & 10b. The
positions of the tape bonding jigs 23 & 24 are also adjusted
according to the cutting position B.
[0053] The chucks 21a & 21b and 22a & 22b are provided
downstream and upstream from the cutting position B, respectively.
Note that the chucks 22a & 22b are configured to be able to
move upstream while grasping the electrode plate 100.
[0054] The tape bonding jigs 23 & 24 are jigs each for sucking
protective tapes one by one and bonding each tape to the surface of
the electrode plate by pressing it against the plate. Specifically,
a vacuum suction pad may be used for this purpose.
[0055] The following explains the steps one by one.
(1) Electrode Plate Cutting (FIG. 3A)
[0056] The electrode plate 100 is conveyed by operation of the
rollers 10a & 10b, and is stopped when a cutting line A reaches
the cutting position B.
[0057] Then, the electrode plate is grasped with the chucks 21a
& 21b and the chucks 22a and 22b, and is cut off with the
cutters 20a & 20b. Thus the electrode plate 100 is cut along
the cutting line A into a preceding electrode plate piece 100a and
a succeeding electrode plate piece 100b. The electrode plate piece
100a has the length required for manufacturing a single cell.
[0058] FIG. 4 illustrates a control mechanism for stopping the
cutting line A at the cutting position B.
[0059] A plurality of reflectance sensors 25a to 25c are arranged
near the cutting position B along the conveyance direction. Each of
the reflectance sensors 25a to 25c irradiates the part of the
electrode plate 100 that passes immediately below the sensor with
light, and receives the reflected light to sequentially obtain the
reflectances. The reflectances are input to a roller drive
controller 26.
[0060] The reflectance of the surface of the electrode plate 100 is
large on the cutting area 102 to which the positive mixture is not
applied, whereas it is small on the positive-mixture layer 104.
That is, the reflectance to be measured by the reflectance sensors
25a to 25c greatly changes at the border (i.e. edge) between the
cutting area 102 and the positive-mixture layer 104. Thus, the
roller drive controller 26 is capable of predicting when the edge
passes immediately below the reflectance sensors 25a to 25c, based
on the reflectances sequentially received from the reflectance
sensors 25a to 25c. The roller drive controller 26 predicts when
the cutting line A reaches the cutting position B, and stops the
rollers 10a & 10b according to the obtained timing. Here, note
that the present embodiment is provided with the cutting areas 102
and the tab areas 103, to which the positive mixture is not
applied. Alternatively, the cutting areas 102 may be configured to
be longer than the tab areas 103, and the distance between the
reflectance sensor 25a and the reflectance sensor 25c may be
configured to be longer than the tab areas 103 (e.g. no less than
10 mm) so that the cutting areas 102 can be detected. Another
method to stop the cutting lines A at the cutting position B is
detecting the tabs 105 attached to the electrode plate 100.
[0061] (2) Pitch Widening (FIG. 3B)
[0062] The chucks 22a & 22b are moved upstream under the
condition that the electrode plate pieces 100a and 100b are both
grasped with the chucks 21a & 21b and the chucks 22a & 22b
respectively, so that a gap W having a constant length is formed
between the upstream-side edge 106 of the electrode plate piece
100a and the downstream-side edge 107 of the electrode plate piece
100b.
[0063] (3) Tape Bonding (FIG. 3C)
[0064] Then, protective tapes 51 and 52 are attached to the
electrode plate pieces 100a and 100b with the tape bonding jigs 23
& 24 so as to cover the gap W kept between the upstream-side
edge 106 and the downstream-side edge 107. Specifically, the
protective tapes are attached such that the electrode plate pieces
100a and 100b are sandwiched between the protective tapes 51 and
52, and the upstream-side edge 106, the downstream-side edge 107
and the gap W therebetween are covered with the protective tapes 51
and 52.
[0065] Here, it is preferable that the protective tapes 51 and 52
are adhesive insulating tapes. Usable base material of the tapes
is, for example, resin of polyolefin such as polyethylene and
polypropylene, polyester, polyimide, polyamide, polyphenylene
sulfide, or the like. Glass cloth tapes are also usable. A
preferable thickness of the base material of the protective tapes
51 and 52 is 10 to 100 .mu.m.
[0066] As FIG. 5A shows, the upstream-side edge 106 of the
preceding electrode plate piece 100a and the downstream-side edge
107 of the succeeding electrode plate piece 100b are connected by
the bonded protective tapes 51 and 52, and the upstream-side edge
106 and the downstream-side edge 107 are covered with the
protective tapes 51 and 52.
[0067] Even if large burrs occur at the edges 106 and 107 in the
electrode plate cutting process described above, the burrs are
pressed with the tape bonding jigs 23 & 24 and are reduced in
size in this tape bonding process.
(4) Electrode Plate Conveying (FIG. 3D)
[0068] The chucks 21a & 21b and the chucks 22a & 22b are
released and the rollers 10a & 10b are driven, so that the
connected electrode plate pieces 100a and 100b are conveyed to the
next stage for the protective tape cutting process.
4. Protective Tape Cutting Process
[0069] FIGS. 6A and 6B illustrate the process for cutting the
protective tapes.
[0070] The protective tape cutting process includes the steps of
protective tape cutting (FIG. 6A) and electrode plate conveying
(FIG. 6B), which are to be performed in the stated order.
[0071] In the stage for the protective tape cutting process, two
pairs of rollers 60a & 60b and 61a & 61b for conveying the
electrode plate 100 are provided downstream and upstream
respectively, in the similar manner as in the stage for the
electrode plate cutting & tape bonding process described above.
The stage is also provided with a pair of cutters 70a & 70b for
cutting the protective tapes and two pairs of chucks 71a & 71b
and 72a & 72b for grasping the protective tapes.
[0072] The cutters 70a & 70b are provided at the cutting
position D between the pair of rollers 60a & 60b and the pair
of rollers 61a & 61b. The pair of chucks 71a & 71b and the
pair of 72a & 72b are provided downstream and upstream from the
cutting position D, respectively.
(1) Protective Tape Cutting (FIG. 6A)
[0073] The rollers 60a & 60b are driven so as to convey the
connected electrode plate pieces 100a and 100b. The electrode plate
pieces 100a and 100b are stopped when the cutting line C (See FIG.
5A and FIG. 7) of the protective tapes 51 and 52 reach the cutting
position D. The mechanism for stopping the cutting line C at the
cutting position D is the same as explained above for the electrode
plate cutting process. The cutting line C positioned within the gap
between the upstream-side edge 106 and the downstream-side edge 107
(e.g. in the middle of the gap), namely in an area where only the
protective tapes 51 and 52 exist and the electrode plate does
not.
[0074] Then, the protective tapes 51 and 52 are grasped with the
chucks 71a & 71b and the chucks 72a and 72b, and are cut off
with the cutters 70a & 70b.
[0075] As FIG. 5B shows, the protective tapes 51 and 52 are cut
along the cutting line C and divided into protective tape pieces
51a and 52a and protective tape pieces 51b and 52b, respectively.
The electrode plate pieces 100a and 100b are separated, but the
upstream-side edge 106 of the electrode plate piece 100a and the
downstream-side edge 107 of the electrode plate piece 100b are kept
covered with the protective tape pieces 51a and 52a and the
protective tape pieces 51b and 52b, respectively.
[0076] FIG. 7 shows that the protective tapes are cut and the
electrode plate pieces 100a and 100b that have been connected are
separated from each other. The electrode plate piece 100b and the
electrode plate piece 100c following it are connected by the
protective tapes 51 and 52.
(2) Electrode Plate Conveying (FIG. 6B)
[0077] The chucks 71a & 71b and the chucks 72a & 72b are
released and the rollers 60a & 60b are driven, so that the
electrode plate piece 100a that has been separated is conveyed to
the next stage for the electrode plate winding process.
5. Electrode Plate Winding Process
[0078] This stage is for manufacturing a wound electrode assembly
as shown in FIG. 8 by winding, from the downstream-side edge 107,
the electrode plate 100a conveyed from the previous stage, to which
the pairs of protective tape pieces 51a & 52a and 51b & 52b
had been bonded, together with an negative electrode plate 200
manufactured separately, such that a separator 300 is sandwiched
therebetween.
[0079] The negative electrode plate 200 is manufactured in the
following manner. A negative-mixture slurry is firstly manufactured
by mixing graphite as a negative-electrode active material and
carboxymethyl cellulose and styrene-butadiene rubber as a binding
agent with water. Then, this slurry is applied to a copper foil
(having the thickness of 8 .mu.m, for example).
[0080] The applied slurry is dried and thus a negative-mixture
layer is formed. Finally, the foil is cut into pieces each having a
predetermine size. As the separator, a microporous polyethylene
film may be used, for example.
[0081] In the wound electrode assembly thus manufactured, the
downstream-side edge 107 (i.e. the starting position of the
winding) of the positive electrode plate piece 100a is kept covered
with the protective tape pieces 51b and 52b, and the ending
position of the winding (i.e. the upstream-side edge 106) is kept
covered with the protective tape pieces 51a and 52a. Hence, even if
burrs occur at the downstream-side edge 107 and the upstream-side
edge 106, short circuit to the negative electrode plate 200 is
prevented.
Advantageous Effects of the Manufacturing Method Pertaining to the
Embodiment
[0082] According to the wound electrode assembly manufacturing
method pertaining to the embodiment described above, the protective
tapes are attached to the cut edges of the electrode plate after
the electrode plate is cut into pieces. Thus, the cut edges are
covered with protective tapes in a preferable manner. As a result,
even if burrs occur at the cut edges, the protective tapes achieve
a sufficient effect of preventing the occurrence of short circuit
in the electrode assembly.
[0083] According to the wound electrode assembly manufacturing
method pertaining to the embodiment described above, in the tape
bonding process, the protective tapes 51 and 52 are integrally
bonded to so as to cover the upstream-side edge 106 of the
electrode plate piece 100a and the downstream-side edge 107 of the
electrode plate piece 100b. Thus, only a single taping operation is
required to bond the protective tapes 51 and 52 to both the
upstream-side edge 106 and the downstream-side edge 107. In other
words, only a single taping operation is required to manufacture
the electrode plate piece for each single cell. Thus, the method
pertaining to the embodiment does not require a long time for the
bonding of the protective tapes.
[0084] Accordingly, the time required for the electrode plate
cutting & tape bonding process and the protective tape cutting
process is reduced, which prevents the increase in takt time in the
winding process.
[0085] Moreover, according to the wound electrode assembly
manufacturing method pertaining to the embodiment described above,
the electrode plate cutting & tape bonding process and the
protective tape cutting process are performed in different stages.
Thus, the method allows the processes to be performed in parallel.
This further reduces the time required for the electrode plate
cutting & tape bonding process and the protective tape cutting
process.
[0086] Furthermore, the stage immediately before the stage for the
electrode plate winding process includes only cutting of the
protective tapes is, and does not include cutting of the electrode
plate. This prevents powder dust and small fragments, generated in
the electrode plate cutting, from being mixed into the electrode
assembly in the electrode plate winding process.
[0087] As described above, the wound electrode assembly
manufacturing method pertaining to the embodiment reduces the time
required for the electrode plate cutting & tape bonding process
and the protective tape cutting process. Thus, it is easy to
complete these processes in a shorter period than the winding of a
one-cell-long electrode plate. This prevents an undesired increase
in takt time of the winding process.
EXAMPLES
[0088] The following shows example sizes of electrode plates to be
manufactured according to the embodiment above, protective tapes to
be bonded to the electrode plates, and so on.
[0089] In FIG. 2, example sizes of the electrode plate 100 are
depicted.
[0090] The width of the electrode plate 100 is 56.8 mm, and the
length corresponding to one cell is 683 mm. The width of each
cutting area 102 is 57.5 mm. The width of each tab area 103 is 10
mm. The length between the cutting area 102 and the tab area 103 is
201 mm.
[0091] In FIGS. 9A to 9C, examples sizes of the part of the
protective tapes 51 and 52 where is bonded to the electrode plate
are depicted.
[0092] In the example depicted in FIG. 9A, the width of each of the
protective tapes 51 and 52 is 16 mm. The length of the gap W
between the upstream-side edge 106 and the downstream-side edge 107
is 6 mm. The margin for bonding of each electrode plate is 5
mm.
[0093] On the side of the upstream-side edge 106, the protective
tapes 51 and 52 are bonded to the cutting area 102 to which the
positive mixture is not applied. However, on the side of the
downstream-side edge 107, the width of the cutting area 102 to
which the positive mixture is not applied is only 3 mm, and thus
the upstream edges of the protective tapes 51 and 52 are bonded to
the positive-mixture layer 104.
[0094] Part of the protective tapes 51 and 52 lies off the
electrode plate for 1 mm from each side of the electrode plate.
[0095] In the example depicted in FIG. 9B, the protective tapes 51
and 52 mentioned above are cut in the middle. The widths of the
protective tape pieces 51a and 51b and the protective tape pieces
51b and 52b are each 8 mm.
[0096] FIG. 9C shows an example case of discarding the protective
tape pieces 51b and 52b, and a part of the electrode plate piece
100b after completing the protective tape cutting process. The
length of the part from the downstream-side edge 107 is 5 mm.
[0097] In such a case, the electrode plate winding process is
performed on the electrode plate 100a with a protective tape piece
attached only to the downstream-side edge.
Modifications
[0098] According to the embodiment described above, the protective
tapes are bonded only to the positive electrode plate. However, it
is possible to bond the protective tapes to the negative electrode
plate in a similar manner. The protective tapes may be bonded only
to the negative electrode plate, or to both the positive electrode
plate and the negative electrode plate.
[0099] According to the embodiment described above, the electrode
plate winding process is performed on the electrode plate 100a
without removing the protective tape pieces 51a and 52a bonded to
the upstream-side edge 106 and the protective tape pieces 51b and
52b bonded to the downstream-side edge 107. However, in the cases
where the protective tape at the starting part of the winding of
the electrode plate piece 100a, the protective tape pieces 51ab and
52b and a downstream-side part (i.e. the vicinity of the
downstream-side edge 107) may be cut off after the completion of
the protective tape cutting process, and then the winding process
may be performed (See FIG. 9C).
[0100] Although the embodiment above is explained based on an
example case of manufacturing an electrode assembly for a
nonaqueous electrolyte battery, the present invention has no
limitation on battery type. The present invention is applicable to
manufacturing of any type of wound electrode assembly.
[0101] Although the present invention has been fully described
byway of examples with reference to the accompanying drawings, it
is to be noted that various changes and modifications will be
apparent to those skilled in the art. Therefore, unless such
changes and modifications depart from the scope of the present
invention, they should be construed as being included therein.
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