U.S. patent application number 15/700322 was filed with the patent office on 2017-12-28 for method for producing separator and device for producing separator.
The applicant listed for this patent is Sumitomo Chemical Company, Limited. Invention is credited to Yasutoshi MINEMOTO, Ryutaro SHIBA.
Application Number | 20170373290 15/700322 |
Document ID | / |
Family ID | 57247438 |
Filed Date | 2017-12-28 |
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United States Patent
Application |
20170373290 |
Kind Code |
A1 |
SHIBA; Ryutaro ; et
al. |
December 28, 2017 |
METHOD FOR PRODUCING SEPARATOR AND DEVICE FOR PRODUCING
SEPARATOR
Abstract
A method for producing a separator in accordance with an
embodiment of the present invention includes: a removing step of
removing both end parts of a separator original sheet in a width
direction of the separator original sheet, the separator original
sheet being transferred; and a coating step of coating, with
coating for forming a heat-resistant layer, the separator original
sheet whose both end parts have been removed in the removing
step.
Inventors: |
SHIBA; Ryutaro;
(Niihama-shi, JP) ; MINEMOTO; Yasutoshi;
(Niihama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sumitomo Chemical Company, Limited |
Tokyo |
|
JP |
|
|
Family ID: |
57247438 |
Appl. No.: |
15/700322 |
Filed: |
September 11, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15333677 |
Oct 25, 2016 |
|
|
|
15700322 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M 10/0525 20130101;
H01M 2/1686 20130101; H01M 2/145 20130101; Y02E 60/10 20130101 |
International
Class: |
H01M 2/14 20060101
H01M002/14; H01M 2/16 20060101 H01M002/16 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 30, 2015 |
JP |
2015-214892 |
Mar 25, 2016 |
JP |
2016-062384 |
Claims
1.-12. (canceled)
13. A method for producing a separator, comprising a removing step
of causing a removing section to remove both end parts of a base
film, which is transferred by being given a tension, in a width
direction of the base film, the width direction being a direction
which is (i) substantially perpendicular to a transferring
direction of the base film and (ii) substantially parallel to a
surface of the base film, the removing section including: a first
cutting section for cutting off one of the both end parts of the
base film; a second cutting section for cutting off the other one
of the both end parts of the base film; and a fixing shaft that
extends in the width direction of the base film and fixes the first
cutting section and the second cutting section.
14. The method for producing a separator as set forth in claim 13,
wherein each of the first cutting section and the second cutting
section is fixable at a given position on the fixing shaft.
15. The method for producing a separator as set forth in claim 13,
wherein each of the first cutting section and the second cutting
section includes a razor blade.
16. The method for producing a separator as set forth in claim 15,
wherein in a case where a distance between a bottom surface of the
base film and a lower end part of a blade edge of the razor blade
of the first cutting section in the removing step is defined as a
first depth, the first depth has a value that is not smaller than a
quarter of a distance between (i) a first end side of the base film
on a side of the one of the both end parts of the base film and
(ii) a removal position at which the razor blade of the first
cutting section is brought into contact with the base film.
17. The method for producing a separator as set forth in claim 15,
wherein in a case where a distance between a bottom surface of the
base film and a lower end part of a blade edge of the razor blade
of the second cutting section in the removing step is defined as a
second depth, the second depth has a value that is not smaller than
a quarter of a distance between (i) a second end side of the base
film on a side of the other one of the both end parts of the base
film and (ii) a removal position at which the razor blade of the
second cutting section is brought into contact with the base
film.
18. A device for producing a separator, comprising a removing
section for removing both end parts of a base film, which is
transferred by being given a tension, in a width direction of the
base film, the width direction being a direction which is (i)
substantially perpendicular to a transferring direction of the base
film and (ii) substantially parallel to a surface of the base film,
the removing section including: a first cutting section for cutting
off one of the both end parts of the base film; a second cutting
section for cutting off the other one of the both end parts of the
base film; and a fixing shaft that extends in the width direction
of the base film and fixes the first cutting section and the second
cutting section.
Description
[0001] This Nonprovisional application claims priority under 35
U.S.C. .sctn.119 on Patent Application No. 2015-214892 filed in
Japan on Oct. 30, 2015 and Patent Application No. 2016-062384 filed
in Japan on Mar. 25, 2016, the entire contents of which are hereby
incorporated by reference.
TECHNICAL FIELD
[0002] The present invention relates to a method and a device for
producing a separator.
BACKGROUND ART
[0003] In production of a separator which is used for a lithium-ion
secondary battery or the like, a functional layer of various kinds
is formed on a separator original sheet which serves as a base. In
regard to such production of a separator, Patent Literature 1
discloses a method for producing a polyethylene microporous film
which is a separator original sheet.
CITATION LIST
Patent Literature
[Patent Literature 1]
[0004] International Publication No. 2013/099539 (Publication Date:
Jul. 4, 2013)
SUMMARY OF INVENTION
Technical Problem
[0005] In a typical production of a separator, while a separator
original sheet unwound from a roll is transferred, a coating step
of coating the separator original sheet with a material for a
functional layer is carried out. However, the separator original
sheet being transferred tends to sag at both end parts thereof, and
have a flare at the both end parts, accordingly. In a case where a
flare occurs at the both end parts of the separator original sheet,
there is a problem that the material for the functional layer, with
which the separator original sheet is coated in the coating step,
has a non-uniform film thickness.
[0006] As a technique for preventing such an occurrence of a flare,
it is possible to set a tension (unwinding tension) of the
separator original sheet high. However, in a case where the tension
of the separator original sheet is set high, there arise new
problems that (i) the separator original sheet may break, (ii) a
wrinkle (longitudinal wrinkle) at a part other than the both end
parts of the separator original sheet is more likely to be formed,
and (iii) the separator original sheet, which is soft, may be
stretched out and deformed.
[0007] An aspect of the present invention has been accomplished in
view of the problems, and an object of the present invention is to
provide a method and a device for producing a separator, each
capable of coating a separator original sheet with a material for a
functional layer in a coating step so that the material has a
uniform film thickness.
Solution to Problem
[0008] In order to attain the object, a method for producing a
separator in accordance with an aspect of the present invention
includes: a removing step of removing both end parts of a base film
in a width direction of the base film, the base film being
transferred; and a coating step of coating, with a material for
forming a functional layer, the base film whose both end parts have
been removed in the removing step.
[0009] In order to attain the object, a method for producing a
separator in accordance with an aspect of the present invention
includes: a removing step of removing both end parts of a base film
in a width direction of the base film, the base film being
transferred; a coating step of coating, with a material for forming
a functional layer, one surface of the base film whose both end
parts have been removed in the removing step; a second removing
step of removing, from the base film having been coated with the
material in the coating step, both end parts of the base film in
the width direction of the base film; and a second coating step of
coating, with a material for forming a functional layer, the other
surface of the base film whose both end parts have been removed in
the second removing step.
[0010] In order to attain the object, a device for producing a
separator in accordance with an aspect of the present invention
includes: a removing section for removing both end parts of a base
film in a width direction of the base film, the base film being
transferred; and a coating section for coating, with a material for
forming a functional layer, the base film whose both end parts have
been removed by the removing section.
[0011] With the configuration, before the base film is coated with
the material by the coating section, the both end parts of the base
film are removed by the removing section. This makes it possible to
coat the base film with the material in a state in which flares
(sags) that occurred at the both end parts of the base film have
been reduced.
[0012] Accordingly, the configuration makes it possible to provide
a device for producing a separator which device is capable of
coating a base film with a material for a functional layer by a
coating section so that the material has a uniform film
thickness.
Advantageous Effects of Invention
[0013] An aspect of the present invention brings about an effect of
providing a method and a device for producing a separator, each
capable of coating a base film with a material for a functional
layer in a coating step so that the material has a uniform film
thickness.
BRIEF DESCRIPTION OF DRAWINGS
[0014] FIG. 1 is a diagram schematically illustrating a cross
sectional configuration of a lithium-ion secondary battery.
[0015] FIG. 2 provides diagrams each schematically illustrating a
state of the lithium-ion secondary battery illustrated in FIG.
1.
[0016] FIG. 3 provides diagrams each schematically illustrating a
state of a lithium-ion secondary battery having another
configuration.
[0017] FIG. 4 is a flow chart schematically showing a method for
producing a separator.
[0018] FIG. 5 is a top surface view illustrating an example of a
removing step shown in FIG. 4.
[0019] FIG. 6 is a cross-sectional view illustrating a positional
relationship between (i) a razor blade included in each of cutting
sections illustrated in FIG. 5 and (ii) a separator original
sheet.
[0020] FIG. 7 is a cross-sectional view showing an example of a
coating step shown in FIG. 4.
[0021] (a) of FIG. 8 is a cross-sectional view illustrating a
configuration of a slitting apparatus for slitting a heat-resistant
separator original sheet. (b) of FIG. 8 is a perspective view
illustrating states before and after the heat-resistant separator
original sheet is slit.
DESCRIPTION OF EMBODIMENTS
[0022] The following description will discuss an embodiment of the
present invention by using, as an example, a separator film
(separator) for a lithium-ion secondary battery.
[0023] First, the lithium-ion secondary battery will be discussed
with reference to FIGS. 1 through 3.
[0024] [Configuration of Lithium Ion Secondary Battery]
[0025] A nonaqueous electrolyte secondary battery, typically, a
lithium-ion secondary battery has a high energy density, and
therefore, is currently widely used not only as batteries for use
in devices such as personal computers, mobile phones, and mobile
information terminals, and for use in moving bodies such as
automobiles and airplanes, but also as stationary batteries
contributing to stable power supply.
[0026] FIG. 1 is a diagram schematically illustrating a cross
sectional configuration of a lithium-ion secondary battery 1. As
illustrated in FIG. 1, the lithium-ion secondary battery 1 includes
a cathode 11, a separator 12, and an anode 13. Between the cathode
11 and the anode 13, an external device 2 is connected outside the
lithium-ion secondary battery 1. Then, while the lithium-ion
secondary battery 1 is being charged, electrons move in a direction
A. On the other hand, while the lithium-ion secondary battery 1 is
being discharged, electrons move in a direction B.
[0027] (Separator)
[0028] The separator 12 is provided so as to be sandwiched between
the cathode 11 which is a positive electrode of the lithium-ion
secondary battery 1 and the anode 13 which is a negative electrode
of the lithium-ion secondary battery 1. The separator 12 separates
the cathode 11 and the anode 13, allowing lithium ions to move
between the cathode 11 and the anode 13. For example, polyolefin
such as polyethylene or polypropylene is used as a material of the
separator 12.
[0029] FIG. 2 provides diagrams each schematically illustrating a
state of the lithium-ion secondary battery 1 illustrated in FIG. 1.
(a) of FIG. 2 illustrates a normal state. (b) of FIG. 2 illustrates
a state in which a temperature of the lithium-ion secondary battery
1 has risen. (c) of FIG. 2 illustrates a state in which a
temperature of the lithium-ion secondary battery 1 has sharply
risen.
[0030] As illustrated in (a) of FIG. 2, the separator 12 is
provided with many pores P. Normally, lithium ions 3 in the
lithium-ion secondary battery 1 can move back and forth through the
pores P.
[0031] However, there are, for example, cases in which the
temperature of the lithium-ion secondary battery 1 rises due to
excessive charging of the lithium-ion secondary battery 1, a high
current caused by short-circuiting of the external device, or the
like. In such cases, the separator 12 melts or softens and the
pores P are blocked as illustrated in (b) of FIG. 2. As a result,
the separator 12 shrinks. This stops the back-and-forth movement of
the lithium ions 3, and consequently stops the above temperature
rise.
[0032] However, in a case where a temperature of the lithium-ion
secondary battery 1 sharply rises, the separator 12 suddenly
shrinks. In this case, as illustrated in (c) of FIG. 2, the
separator 12 may be destroyed. Then, the lithium ions 3 leak out
from the separator 12 which has been destroyed. As a result, the
lithium ions 3 do not stop moving back and forth. Consequently, the
temperature continues rising.
[0033] (Heat-Resistant Separator)
[0034] FIG. 3 provides diagrams each schematically illustrating a
state of a lithium-ion secondary battery 1 having another
configuration. (a) of FIG. 3 illustrates a normal state, and (b) of
FIG. 3 illustrates a state in which a temperature of the
lithium-ion secondary battery 1 has sharply risen.
[0035] As illustrated in (a) of FIG. 3, the lithium-ion secondary
battery 1 can further include a heat-resistant layer 4. The
heat-resistant layer 4 can be provided to the separator 12. (a) of
FIG. 3 illustrates a configuration in which the separator 12 is
provided with the heat-resistant layer 4 serving as a functional
layer. A film in which the separator 12 is provided with the
heat-resistant layer 4 is hereinafter referred to as a
heat-resistant separator (separator) 12a.
[0036] In the configuration illustrated in (a) of FIG. 3, the
heat-resistant layer 4 is laminated on a surface of the separator
12 which surface is on a cathode 11 side. Note that the
heat-resistant layer 4 can alternatively be laminated on a surface
of the separator 12 which surface is on an anode 13 side, or both
surfaces of the separator 12. Further, the heat-resistant layer 4
is provided with pores which are similar to the pores P. Normally,
the lithium ions 3 move back and forth through the pores P and the
pores of the heat-resistant layer 4. The heat-resistant layer 4
contains, for example, wholly aromatic polyamide (aramid resin) as
a material.
[0037] As illustrated in (b) of FIG. 3, even in a case where the
temperature of the lithium-ion secondary battery 1 sharply rises
and as a result, the separator 12 melts or softens, the shape of
the separator 12 is maintained because the heat-resistant layer 4
supports the separator 12. Therefore, such a sharp temperature rise
results in only melting or softening of the separator 12 and
consequent blocking of the pores P. This stops the back-and-forth
movement of the lithium ions and consequently stops the
above-described excessive discharging or excessive charging. In
this way, the separator 12 can be prevented from being
destroyed.
[0038] [Flow for Producing Separator]
[0039] The following description will discuss a flow for producing
a separator.
[0040] FIG. 4 is a flow chart schematically showing a method for
producing a separator. The separator is configured such that a
functional layer is laminated on a separator original sheet (base
film) which serves as a base. A film made of polyethylene or the
like is used for the separator original sheet. Examples of the
functional layer encompass a heat-resistant layer and an adhesive
layer.
[0041] The functional layer is laminated on the separator original
sheet by (i) coating the separator original sheet with coating (a
material) or the like corresponding to the functional layer and
then (ii) drying the separator original sheet.
[0042] FIG. 4 shows, as an example, a flow for producing the
heat-resistant separator 12a in a case where the functional layer
is the heat-resistant layer 4. The flow shown in FIG. 4 is an
example of a flow in which wholly aromatic polyamide (aramid resin)
employed as a material for the heat-resistant layer 4 is laminated
on a polyethylene base film which is a separator original sheet
(base film) 12d.
[0043] The above flow includes an inspection step S1, a removing
step S2, a coating step S3, a precipitating step S4, a washing step
S5, a drying step S6, an inspection step S7, and a slitting step
S8.
[0044] Note that a method for producing a separator in accordance
with an aspect of the present invention can include, before the
inspection step S1, a step of producing the separator original
sheet 12d. Further, the inspection step S1 can be omitted.
Alternatively, the inspection step S1 can be carried out between
the removing step S2 and the coating step S3.
[0045] The method for producing a separator in accordance with an
aspect of the present invention can include a second removing step
S2-2 after the drying step S6. In this case, a flow for producing a
separator includes the inspection step S1, the removing step S2,
the coating step S3, the precipitating step S4, the washing step
S5, the drying step S6, the second removing step S2-2, the
inspection step S7, and the slitting step S8.
[0046] In the method for producing a separator in accordance with
an aspect of the present invention, the precipitating step S4 and
the washing step S5 can be omitted. This is because the
precipitating step S4 and the washing step S5 can be unnecessary
depending on a configuration of the functional layer and a
configuration of coating used in the coating step S3. In this case,
a flow for producing a separator includes the inspection step S1,
the removing step S2, the coating step S3, the drying step S6, the
inspection step S7, and the slitting step S8.
[0047] The method for producing a separator in accordance with an
aspect of the present invention can include, after the drying step
S6, the second removing step S2-2, a second coating step S3-2, a
second precipitating step S4-2, a second washing step S5-2, and a
second drying step S6-2. In this case, a flow for producing a
separator includes the inspection step S1, the removing step S2,
the coating step S3, the precipitating step S4, the washing step
S5, the drying step S6, the second removing step S2-2, the second
coating step S3-2, the second precipitating step S4-2, the second
washing step S5-2, the second drying step S6-2, the inspection step
S7, and the slitting step S8. In the above flow, it is possible to
omit (i) the precipitating step S4 and the washing step S5 and (ii)
the second precipitating step S4-2 and the second washing step
S5-2. This is because, as described above, the precipitating step
S4 and the washing step S5 and (ii) the precipitating step S4-2 and
the washing step S5-2 can be unnecessary depending on (i) the
configuration of the functional layer and (ii) the structure of the
coating used in the coating step S3. In this case, a flow for
producing a separator includes the inspection step S1, the removing
step S2, the coating step S3, the drying step S6, the second
removing step S2-2, the second coating step S3-2, the second drying
step S6-2, the inspection step S7, and the slitting step S8.
[0048] The method for producing a separator in accordance with an
aspect of the present invention can further include an additional
inspection step between the steps.
[0049] (Production Step of Producing Separator Original Sheet)
[0050] First, the following description will discuss production of
the separator original sheet 12d serving as a base film, by using,
as an example, a case where the separator original sheet 12d mainly
contains polyethylene as a material.
[0051] The following description will discuss, as an example, a
production method for producing the separator original sheet 12d in
which production method a thermoplastic resin in which a pore
forming agent is added is shaped into a film and then the pore
forming agent is removed by use of an appropriate solvent.
Specifically, in a case where a polyethylene resin containing an
ultrahigh molecular weight polyethylene is used as a material of
the separator original sheet 12d, steps (A) through (D) below are
sequentially carried out in the production method.
[0052] (A) Kneading Step
[0053] A step of obtaining a polyethylene resin composition by
kneading an ultrahigh molecular weight polyethylene and an
inorganic filler such as a calcium carbonate.
[0054] (B) Rolling Step
[0055] A step of forming a film by use of the polyethylene resin
composition obtained in the kneading step.
[0056] (C) Removal Step
[0057] A step of removing the inorganic filler from the film
obtained in the rolling step.
[0058] (D) Stretching Step
[0059] A step of obtaining the separator original sheet 12d by
stretching the film obtained in the removal step.
[0060] According to the above production method, in the removal
step (C), many fine pores are provided in the film. The fine pores
of the film stretched in the stretching step (D) become the
above-described pores P. The separator original sheet 12d formed as
a result is a polyethylene microporous film having a prescribed
thickness and a prescribed air permeability.
[0061] In the kneading step (A), 100 parts by weight of the
ultrahigh molecular weight polyethylene, 5 parts by weight to 200
parts by weight of a low-molecular weight polyolefin having a
weight-average molecular weight of not more than 10000, and 100
parts by weight to 400 parts by weight of the inorganic filler can
be kneaded.
[0062] Note that even in a case where the separator original sheet
12d contains another material, the separator original sheet 12d can
be produced by similar production steps. The method for producing
the separator original sheet 12d is not limited to the method in
which the pore forming agent is removed, and various methods can be
used for producing the separator original sheet 12d.
[0063] The following description will sequentially discuss the
steps S1 through S8 which are subsequent to the production step of
producing the separator original sheet 12d. Note that the steps S1
through S8 are carried out in this order.
[0064] (Inspection Step S1)
[0065] The inspection step S1 is a step of inspecting, before a
subsequent step, the separator original sheet 12d which serves as a
base of the heat-resistant separator 12a.
[0066] (Removing Step S2)
[0067] The removing step S2 is a step of removing, from the
separator original sheet 12d which has been inspected in the
inspection step S1, both end parts (edge parts) of the separator
original sheet 12d in a width direction thereof. In other words,
the removing step S2 is a step of removing both end parts of the
separator original sheet 12d which both end parts face each other
in a direction substantially perpendicular to a transferring
(longitudinal) direction of the separator original sheet 12d.
[0068] As described above, the separator original sheet 12d tends
to sag at an end part thereof while being transferred, and this
causes a flare at the end part. In a case where a flare occurs at
the end part of the separator original sheet 12d, coating for the
heat-resistant layer 4, with which the separator original sheet 12d
is coated in the coating step S3, has a non-uniform film
thickness.
[0069] Therefore, Embodiment 1 involves removing the both end
parts, at each of which a flare has occurred, from the separator
original sheet 12d in the removing step S2, before the coating step
S3.
[0070] FIG. 5 is a top surface view illustrating an example of the
removing step S2 shown in FIG. 4. As illustrated in FIG. 5, the
removing step S2 is carried out by a removing device (removing
section) 5 for removing both end parts (removal parts) e of the
separator original sheet 12d.
[0071] The removing device 5 includes (i) two cutting sections
(first cutting section, second cutting section) 51 for removing
(cutting off) the respective both end parts e of the separator
original sheet 12d and (ii) a fixing shaft 52 for fixing the
cutting sections 51.
[0072] The fixing shaft 52 has a substantially linear shape
extending in the width direction of the separator original sheet
12d. Both end parts of the fixing shaft 52 are fixed to respective
fixing sections 6 that are provided on respective both sides of the
removing device 5 so as to sandwich the removing device 5.
[0073] As described above, in the removing device 5, the fixing
shaft 52 for fixing the cutting sections 51 has a substantially
linear shape, and the two cutting sections 51 are fixed to the
single fixing shaft 52. This allows the cutting sections 51 to be
more stable as compared with, for example, a case where the two
cutting sections 51 are fixed to respective different members. This
allows the cutting sections 51 to appropriately remove the both end
parts e of the separator original sheet 12d at respective removal
positions C.
[0074] The cutting sections 51 can each be configured to be fixable
at a given position on the fixing shaft 52. This makes it possible
to set a width of the separator original sheet 12d to a given value
in the removing step S2.
[0075] The cutting sections 51 each include a razor blade 512 (see
FIG. 6). The razor blade 512 removes corresponding one of the both
end parts e of the separator original sheet 12d by a blade edge
512a that has been sharpened. This makes it possible to provide a
separator original sheet (base film) 12c which (i) is obtained by
removing, from the separator original sheet 12d, the both end parts
e at each of which a flare has occurred and (ii) is thus flat.
[0076] FIG. 6 is a cross-sectional view illustrating a positional
relationship between (i) the razor blade 512 included in each of
the cutting sections 51 illustrated in FIG. 5 and (ii) the
separator original sheet 12d. As illustrated in FIG. 6, the razor
blade 512 is provided so as to be obliquely inclined with respect
to the separator original sheet 12d so that the blade edge 512a
forms an angle .theta. with respect to the separator original sheet
12d that is being transferred.
[0077] The razor blade 512 used in Embodiment 1 is a long blade
having a blade length greater than that of a slitting razor blade
(short blade) which is typically used in production of a separator.
Accordingly, in a case where a distance between a bottom surface of
the separator original sheet 12d and a lower end part (cutting
point) of the blade edge 512a is defined as a depth D, it is
possible to set the depth D to be greater as compared with a
conventional razor blade.
[0078] By setting the depth D to be thus greater, it is possible to
appropriately remove, from the separator original sheet 12d by
using the razor blade 512, the both end parts e at each of which a
flare has occurred.
[0079] Note that a width of a flare (i.e., a width of the flare as
measured in an out-of-plane direction of the separator original
sheet 12d) varies in accordance with factors such as a size, a
transferring speed, and an unwinding tension of the separator
original sheet 12d. Accordingly, a value of the depth D is set as
appropriate in accordance with a width of a flare that has occurred
at each of the both end parts e of the separator original sheet
12d.
[0080] The value of the depth D is preferably not smaller than a
quarter of a distance between (i) each of both end sides E of the
separator original sheet 12d, which is being transferred, in the
width direction of the separator original sheet 12d and (ii)
corresponding one of the removal positions C at each of which the
razor blade 512 is brought into contact with the separator original
sheet 12d. In a case where the value of the depth D is not smaller
than a quarter of the above distance, it is possible to more
appropriately remove, from the separator original sheet 12d by
using the razor blade 512, the both end parts e at each of which a
flare has occurred.
[0081] An upper limit of the depth D is preferably equal to the
above distance. In a case where the value of the depth D exceeds
the above distance, (i) it is difficult to secure a space
sufficient for mounting the cutting sections 51, due to a
configuration of the removing device 5 and (ii) the blade edge 512a
of the razor blade 512 is used less efficiently. It is therefore
not reasonable to set the value of the depth D to be greater than
the above distance.
[0082] A width of each of the removal parts (both end parts e)
removed in the removing step S2 is preferably not smaller than 5 mm
but not greater than 200 mm. In terms of a reliable removal of a
part in which a flare can occur, the width of each of the removal
parts (both end parts e) removed in the removing step S2 is
preferably not smaller than 5 mm, more preferably not smaller than
8 mm, and still more preferably not smaller than 10 mm. Meanwhile,
in terms of a yield of a product which is obtained after the
removal parts are removed, the above width is preferably not
greater than 200 mm, and more preferably not greater than 150 mm.
The removal parts (both end parts e) each having a width of less
than 5 mm is unsuitable because, in such a case, it is difficult to
remove the both end parts e from the separator original sheet 12d
which is thin and low in strength.
[0083] The removal parts that are removed in the removing step S2
can have respective different widths. In a case where a removal
part in which a flare is more likely to occur is removed by a
larger portion, it is possible to prevent an occurrence of a flare
without reducing an overall yield in the production of
separators.
[0084] Note that a type of the blade used in the removing step S2
is not particularly limited and various types of blades can be
used, provided that it is possible to remove, by the blade, the
both end parts e of the separator original sheet 12d. For example,
instead of the razor blade 512, it is possible to use a blade such
as a circular blade.
[0085] (Coating Step S3)
[0086] The coating step S3 is a step of coating, with coating (a
material) for the heat-resistant layer 4, a separator original
sheet 12c which is obtained by removing the both end parts e from
the separator original sheet 12d in the removing step S2. In the
coating step S3, it is possible to carry out the coating with
respect to only one surface of the separator original sheet 12c or
both surfaces of the separator original sheet 12c. In a case where
the coating is carried out with respect to only one surface of the
separator original sheet 12c, it is possible to further carry out
coating with respect to the other surface of the separator original
sheet 12c in the second coating step S3-2 described later.
[0087] For example, in the coating step S3, the separator original
sheet 12c is coated with a solution in which aramid is dissolved in
NMP (N-methylpyrrolidone), as coating for the heat-resistant layer.
Note that the heat-resistant layer 4 is not limited to an aramid
heat-resistant layer. For example, it is possible to coat the
separator original sheet 12c with a suspension of alumina,
carboxymethyl cellulose, and water, as the coating for the
heat-resistant layer.
[0088] According to Embodiment 1, no other step is carried out
between the removing step S2 and the coating step S3, and after the
both end parts e at each of which a flare has occurred are removed
in the removing step S2, the coating is carried out with respect to
the separator original sheet 12c in the coating step S3, which is
subsequent to the removing step S2. This makes it possible to carry
out the coating with respect to the separator original sheet 12c
while suitably maintaining flatness of the separator original sheet
12c. Accordingly, it is possible to coat the separator original
sheet 12c with the material for the heat-resistant layer 4 so that
the material has a more uniform film thickness.
[0089] Note, however, that another step (e.g., a winding step etc.)
can be carried out between the removing step S2 and the coating
step S3. Even in a case where another step is carried out between
the removing step S2 and the coating step S3, it is possible, by
carrying out the removing step S2 of removing the both end parts e
of the separator original sheet 12d before the coating step S3, to
coat the separator original sheet 12c with the material for the
heat-resistant layer 4 so that the material has a more uniform film
thickness as compared with a case where the removing step S2 is not
carried out.
[0090] FIG. 7 is a cross-sectional view showing an example of the
coating step S3 shown in FIG. 4. As shown in FIG. 7, the coating
step S3 is carried out by a coating device (coating section) 7 for
coating, with coating 74 for the heat-resistant layer, the
separator original sheet 12c which is obtained by removing the both
end parts e from the separator original sheet 12d in the removing
step S2.
[0091] The coating device 7 has a mechanism of a bar coater method
and includes a coating dropper 71, a coating bar 72, and a coating
bar driving section 73. According to the mechanism, the coating is
carried out with respect to the separator original sheet 12c in the
following manner. That is, a gap (clearance) is provided between a
tip of the coating bar 72 and the separator original sheet 12c, and
the separator original sheet 12c is transferred while coating 74
that has been dropped from the coating dropper 71 onto the
separator original sheet 12c is being accumulated on one side of
the coating bar 72 (i.e., upstream of the coating bar 72 in a
transferring direction of the separator original sheet 12c).
[0092] Note that a method for coating the separator original sheet
12c with the coating 74 is not specifically limited as long as
uniform wet coating can be performed with respect to the separator
original sheet 12c by the method. The method can be any of various
methods such as a capillary coating method, a slit die coating
method, a spray coating method, a dip coating method, a roll
coating method, a screen printing method, a flexo printing method,
a bar coater method, a gravure coater method, or a die coater
method.
[0093] A material for the heat-resistant layer 4 with which
material the separator original sheet 12c is coated has a film
thickness that can be controlled by adjusting a thickness of a
coating wet film and a solid-content concentration in the coating
solution.
[0094] In the coating step S3, the separator original sheet 12c
obtained by removing the both end parts e from the separator
original sheet 12d is preferably coated with the coating 74 so that
surfaces of respective both edge parts of the separator original
sheet 12c in a width direction of the separator original sheet 12c
are left uncoated as uncoated parts (edge-uncoated coating). This
can prevent the coating 74 from flowing around from the both end
parts of the separator original sheet 12c to a back surface of the
separator original sheet 12c, unlike in a case where an entire
surface coating is carried out so that the coating 74 is applied to
the separator original sheet 12c so as to cover up to the surfaces
of the respective both edge parts of the separator original sheet
12c. Accordingly, it is possible to reduce a product defect which
is caused when the coating 74 flows around to the back surface of
the separator original sheet 12c.
[0095] In this case, the uncoated parts can be removed in a step to
be carried out later (e.g., the second removing step S2-2, the
slitting step S8, etc. (described later)). This makes it possible
to produce the heat-resistant separator 12a in which the
heat-resistant layer 4 has a more uniform film thickness.
[0096] (Precipitating Step S4)
[0097] The precipitating step S4 is a step of solidifying the
coating 74 with which the separator original sheet 12c has been
coated in the coating step S3. In a case where the coating 74 is an
aramid coating, for example, water vapor is applied to a coated
surface so that aramid is solidified by humidity precipitation.
This provides a heat-resistant separator original sheet 12b (see
FIG. 8) in which the heat-resistant layer 4 is formed on the
separator original sheet 12c.
[0098] (Washing Step S5)
[0099] The washing step S5 is a step of washing the heat-resistant
separator original sheet 12b in which the coating has been
solidified in the precipitating step S4. In a case where the
heat-resistant layer 4 is an aramid heat-resistant layer, for
example, water, an aqueous solution, or an alcohol-based solution
is suitably used as a washing liquid.
[0100] (Drying Step S6)
[0101] The drying step S6 is a step of drying the heat-resistant
separator original sheet 12b that has been washed in the washing
step S5. A method for drying the heat-resistant separator original
sheet 12b is not particularly limited, and, for example, it is
possible to use various methods such as a method in which the
heat-resistant separator original sheet 12b is brought into contact
with a heated roll or a method in which hot air is blown onto the
heat-resistant separator original sheet 12b.
[0102] (Second Removing Step S2-2)
[0103] A method for producing the heat-resistant separator 12a can
include, after the drying step S6, the second removing step S2-2 of
further removing both end parts of the heat-resistant separator
original sheet 12b. This makes it possible to suitably prevent a
wrinkle from occurring on the heat-resistant separator original
sheet 12b while the heat-resistant separator original sheet 12b is
being transferred.
[0104] Particularly, in a case where the edge-uncoated coating has
been carried out with respect to the separator original sheet 12c
in the coating step S3, there is a level difference (a boundary
between a coated part and an uncoated part) at the both end parts
of the separator original sheet 12c due to the film thickness of
the heat-resistant layer 4. Accordingly, a wrinkle may be caused by
the level difference.
[0105] In a case where the both end parts, which are uncoated
parts, of the heat-resistant separator original sheet 12b are
removed in the second removing step S2-2 so that the level
difference is eliminated, it is possible to prevent a wrinkle from
occurring on the heat-resistant separator original sheet 12b while
the heat-resistant separator original sheet 12b is being
transferred.
[0106] That is, removal parts which are removed in the second
removing step S2-2 each preferably include the uncoated part and a
part of the coated part. In other words, in order to reliably
include the entire uncoated parts in the removal parts, it is
preferable to also include, in each of the removal parts, a part of
the coated part which part is adjacent to the uncoated part when
the both end parts of the heat-resistant separator original sheet
12b are removed in the second removing step S2-2.
[0107] For example, in a case where the edge-uncoated coating has
been carried out in the coating step S3 so that a part which is
approximately 10 mm in width as measured from each of the both end
sides E of the separator original sheet 12c is left uncoated as an
uncoated part, a part of the coated part which part has a width of
not smaller than 5 mm but not greater than 80 mm is removed, in
addition to the uncoated part of approximately 10 mm in width, from
the separator original sheet 12b at each of the both end sides E of
the heat-resistant separator original sheet 12b in the second
removing step S2-2. Specific aspect (means) of the second removing
step S2-2 is identical to that of the removing step S2.
[0108] In terms of (i) a reliable removal of a part in which a
flare can occur and (ii) a reliable elimination of a level
difference caused by a film thickness of a material (functional
layer) with which one surface of the base film has been coated, a
width of the part of the coated part which part is removed in the
removing step S2-2 is preferably not smaller than 5 mm, more
preferably not smaller than 8 mm, and still more preferably not
smaller than 10 mm. Meanwhile, in terms of a yield of a product
which is obtained after the removal parts are removed, the above
width is preferably not greater than 80 mm, and more preferably not
greater than 50 mm.
[0109] In a case where the heat-resistant separator original sheet
12b includes the heat-resistant layer 4 only on one surface of the
heat-resistant separator original sheet 12b, it is possible to form
a heat-resistant layer 4 also on the other surface of the resistant
separator original sheet 12b by carrying out the second coating
step S3-2, the second precipitating step S4-2, the second washing
step S5-2, and the second drying step S6-2, subsequent to the
second removing step S2-2.
[0110] That is, the method for producing a separator in accordance
with an aspect of the present invention can be carried out by
using, as a base film, the heat-resistant separator original sheet
12b including the heat-resistant layer 4 only on one surface of the
heat-resistant separator original sheet 12b.
[0111] (Second Coating Step S3-2)
[0112] The second coating step S3-2 is a step of coating the other
surface of the heat-resistant separator original sheet 12b with
coating (a material) for the heat-resistant layer 4. For example,
no other step is carried out between the second removing step S2-2
and the second coating step S3-2 and, after the both end parts of
the heat-resistant separator original sheet 12b are removed in the
second removing step S2-2, the coating is carried out with respect
to the other surface of the heat-resistant separator original sheet
12b in the second coating step S3-2, which is subsequent to the
second removing step S2-2. As a result, the coating is carried out
while flatness of the heat-resistant separator original sheet 12b
is suitably maintained. This makes it possible to coat the
heat-resistant separator original sheet 12b with the material for
the heat-resistant layer 4 so that the material has a more uniform
film thickness. Specific aspect (means) of the second coating step
S3-2 is identical to that of the coating step S3.
[0113] (Second Precipitating Step S4-2)
[0114] The second precipitating step S4-2 is a step of solidifying
the coating with which the heat-resistant separator original sheet
12b has been coated in the second coating step S3-2. Specific
aspect (means) of the second precipitating step S4-2 is identical
to that of the precipitating step S4.
[0115] (Second Washing Step S5-2)
[0116] The second washing step S5-2 is a step of washing the
heat-resistant separator original sheet 12b on which the coating
has been solidified in the second precipitating step S4-2. Specific
aspect (means) of the second washing step S5-2 is identical to that
of the washing step S5.
[0117] (Second Drying Step S6-2)
[0118] The second drying step S6-2 is a step of drying the
heat-resistant separator original sheet 12b that has been washed in
the second washing step S5-2. Specific aspect (means) of the second
drying step S6-2 is identical to that of the drying step S6.
[0119] (Inspection Step S7)
[0120] The inspection step S7 is a step of inspecting the
heat-resistant separator original sheet 12b that has been dried in
the drying step S6 (the second drying step S6-2 in a case where the
flow includes the drying step S6-2). In a case where the
heat-resistant separator original sheet 12b is inspected, it is
possible to mark a defective part as appropriate so that the
defective part can be easily removed.
[0121] (Slitting Step S8)
[0122] The slitting step S8 is a step of slitting (cutting) the
heat-resistant separator original sheet 12b inspected in the
inspection step S7 into parts each having a predetermined product
width. Specifically, in the slitting step S8, the heat-resistant
separator original sheet 12b is slit into parts each having a
product width which is suitable for an applied product such as the
lithium-ion secondary battery 1.
[0123] In order to increase productivity, the heat-resistant
separator original sheet 12b is usually produced so as to have a
width that is equal to or greater than the product width. After the
heat-resistant separator original sheet 12b is produced, the
heat-resistant separator original sheet 12b is slit into
heat-resistant separators 12a each having the product width.
[0124] In the slitting step S8, it is possible to remove both end
parts of the heat-resistant separator original sheet 12b, at the
same time as slitting the heat-resistant separator original sheet
12b. In a case where redundant films are removed from the
respective both end parts of the heat-resistant separator original
sheet 12b in the slitting step S8, it is possible to suitably
process the heat-resistant separator original sheet 12b into the
heat-resistant separators 12a each having the product width.
[0125] In a case where the edge-uncoated coating has been carried
out in the coating step S3 (the second coating step S3-2 in a case
where the flow includes the second coating step S3-2), uncoated
parts F (see FIG. 8) are removed in the slitting step S8. For
example, in a case where the edge-uncoated coating has been carried
out in the coating step S3 (or the second coating step S3-2) so
that a part which is approximately 10 mm in width as measured from
each of the both end sides E of the separator original sheet 12c is
left uncoated as an uncoated part F, a part of the coated part
which part has a width of not smaller than 5 mm but not greater
than 80 mm is removed, in addition to the uncoated part F of
approximately 10 mm in width, from the heat-resistant separator
original sheet 12b at each of the both end sides E of the
heat-resistant separator original sheet 12b.
[0126] (a) of FIG. 8 is a cross-sectional view illustrating a
configuration of a slitting apparatus 8 for slitting the
heat-resistant separator original sheet 12b. (b) of FIG. 8 is a
perspective view illustrating states before and after the
heat-resistant separator original sheet 12b is slit.
[0127] As illustrated in (a) of FIG. 8, the slitting apparatus 8
includes a wind-off roller 81, rollers 82 through 85, and a
plurality of take-up rollers 86 each of which (i) has a columnar
shape and (ii) is rotatably supported. The slitting apparatus 8
further includes a plurality of blades (not illustrated).
[0128] In the slitting apparatus 8, a core 87 which has a
cylindrical shape and on which the heat-resistant separator
original sheet 12b is wound is fitted on the wind-off roller 81.
The heat-resistant separator original sheet 12b is unwound from the
core 87 to a path U or a path L. The heat-resistant separator
original sheet 12b thus unwound is transferred to the roller 84 via
the roller 83 at, for example, a speed of 100 m/min. In a step of
transferring the heat-resistant separator original sheet 12b, the
heat-resistant separator original sheet 12b is slit substantially
parallel to a transferring (longitudinal) direction. As a result, a
plurality of heat-resistant separators 12a, into which the
heat-resistant separator original sheet 12b are slit so as to have
the product width, are produced.
[0129] As illustrated in (b) of FIG. 8, the plurality of
heat-resistant separators 12a thus produced are wound on respective
cores 88 fitted on the take-up rollers 86.
[0130] Note that the method for producing the heat-resistant
separator 12a can include a step other than the steps described
above. For example, the method for producing the heat-resistant
separator 12a can include a water removing step between the washing
step S5 and the drying step S6 or between the second washing step
S5-2 and the second drying step S6-2. In the water removing step,
water or the like adhered to the heat-resistant separator original
sheet 12b is removed in order to prevent the heat-resistant
separator original sheet 12b from insufficiently being dried in the
subsequent step, i.e., the drying step S6 or the second drying step
S6-2.
[0131] Alternatively, the method for producing the heat-resistant
separator 12a can include, instead of the slitting step S8, a
winding step of winding the heat-resistant separator original sheet
12b that has been inspected in the inspection step S7. For example,
a core having a cylindrical shape can be used for winding the
heat-resistant separator original sheet 12b. The heat-resistant
separator original sheet 12b that has been wound can be, for
example, shipped as it is with a wide width, as an original sheet
of the heat-resistant separator 12a. In this case, the slitting
step S8 is omitted.
[0132] [Main Points]
[0133] As described above, the method for producing the
heat-resistant separator 12a in accordance with Embodiment 1
includes: the removing step S2 of removing the both end parts e of
the separator original sheet 12d, which is being transferred, in
the width direction of the separator original sheet 12d to thereby
obtain the separator original sheet 12c; and the coating step S3 of
coating the separator original sheet 12c with the coating for
forming the heat-resistant layer 4.
[0134] With the configuration, the both end parts e of the
separator original sheet 12d are removed in the removing step S2,
before the coating step S3. This makes it possible to coat the
separator original sheet 12c with the coating in a state in which
flares (sags) that occurred at each of the both end parts e of the
separator original sheet 12d have been reduced.
[0135] Therefore, according to Embodiment 1, it is possible to
provide a method for producing the heat-resistant separator 12a
which method is capable of coating the separator original sheet 12c
with the coating for the heat-resistant layer 4 in the coating step
S3 so that the coating has a uniform film thickness.
[0136] The present invention is not limited to the embodiments, and
can be altered by a skilled person in the art within the scope of
the claims. An embodiment derived from a proper combination of
technical means each disclosed in a different embodiment is also
encompassed in the technical scope of the present invention.
[0137] [Remarks]
[0138] A method for producing a separator in accordance with
Embodiment 1 includes: a removing step of removing both end parts
of a base film in a width direction of the base film, the base film
being transferred; and a coating step of coating, with a material
for forming a functional layer, the base film whose both end parts
have been removed in the removing step.
[0139] With the configuration, the both end parts of the base film
(separator original sheet) are removed in the removing step, before
the coating step. This makes it possible to coat the base film with
the material in a state in which flares (sags) that occurred at
each of the both end parts of the base film have been reduced.
[0140] Accordingly, the configuration makes it possible to provide
a method for producing a separator which method is capable of
coating a base film with a material for a functional layer in a
coating step so that the material has a uniform film thickness.
[0141] Note that, according to Embodiment 1, "a width direction of
a base film" means a direction which is (i) substantially
perpendicular to a transferring (longitudinal) direction of the
base film and (ii) substantially parallel to a surface of the base
film.
[0142] A method for producing a separator in accordance with
Embodiment 1 preferably further includes a second removing step of
removing, from the base film having been coated with the material
in the coating step, both end parts of the base film in the width
direction of the base film.
[0143] With the configuration, the both end parts of the base film
that has been coated with the material is further removed in the
second removing step. This makes it possible to suitably prevent a
wrinkle from occurring on the base film while the base film is
being transferred.
[0144] A method for producing a separator in accordance with
Embodiment 1 includes: a removing step of removing both end parts
of a base film in a width direction of the base film, the base film
being transferred; a coating step of coating, with a material for
forming a functional layer, one surface of the base film whose both
end parts have been removed in the removing step; a second removing
step of removing, from the base film having been coated with the
material in the coating step, both end parts of the base film in
the width direction of the base film; and a second coating step of
coating, with a material for forming a functional layer, the other
surface of the base film whose both end parts have been removed in
the second removing step.
[0145] With the configuration, the both end parts of the base film
(separator original sheet) are removed in the removing step, before
the coating step. This makes it possible to coat one surface of the
base film in the coating step in a state in which flares (sags)
that occurred at each of the both end parts of the base film have
been reduced.
[0146] With the configuration, the both end parts of the base film
(separator original sheet) are removed in the second removing step,
before the second coating step. This makes it possible to coat the
other surface of the base film in the second coating step in a
state in which flares (sags) that occurred at each of the both end
parts of the base film have been reduced. Further, with the
configuration, the both end parts of the base film that has been
coated with the material is further removed in the second removing
step. This makes it possible to suitably prevent a wrinkle from
occurring on the base film while the base film is being
transferred.
[0147] Accordingly, the configuration makes it possible to provide
a method for producing a separator which method is capable of
coating both surfaces of a base film with a material for a
functional layer so that the material has a uniform film
thickness.
[0148] The method for producing a separator in accordance with
Embodiment 1 is preferably configured such that each of the both
end parts of the base film which both end parts are removed in the
second removing step includes a part of a coated part of the base
film that has been coated with the material in the coating
step.
[0149] With the configuration, it is possible to eliminate a level
difference between a coated part and a non-coated part which level
difference is caused by a film thickness of the material
(functional layer) with which one surface of the base film has been
coated.
[0150] Accordingly the configuration makes it possible to prevent a
wrinkle caused by the level difference.
[0151] The method for producing a separator in accordance with
Embodiment 1 is preferably configured such that the part of the
coated part which part is removed in the second removing step has a
width of not smaller than 5 mm but not greater than 80 mm.
[0152] With the configuration, it is possible to appropriately
remove the both end parts of the base film which both end parts are
located in an area in which a flare can occur. Further, with the
configuration, in a case where the both end parts of the base film
coated with the material are appropriately removed, it is possible
to suitably prevent a wrinkle from occurring on the base film while
the base film is being transferred.
[0153] The method for producing a separator in accordance with
Embodiment 1 is preferably configured such that each of the both
end parts of the base film which both end parts are removed in the
removing step has a width of not smaller than 5 mm but not greater
than 200 mm.
[0154] With the configuration, it is possible to appropriately
remove the both end parts of the base film which both end parts are
located in an area in which a flare can occur.
[0155] A method for producing a separator in accordance with
Embodiment 1 preferably further includes a slitting step of
slitting, into parts each having a predetermined product width, the
base film that has been coated with the material.
[0156] With the configuration, in a case where the base film is
slit into parts each having a predetermined product width in the
slitting step, it is possible to obtain a separator in which a
functional layer has a uniform film thickness.
[0157] The method for producing a separator in accordance with
Embodiment 1 is preferably configured such that the slitting step
includes removing, at the same time as slitting the base film which
has been coated with the material, both end parts of the base film
in the width direction of the base film.
[0158] With the configuration, in a case where redundant films are
removed from the both end parts of the base film in the slitting
step, it is possible to suitably process the base film into parts
each having a product width.
[0159] The method for producing a separator in accordance with
Embodiment 1 is preferably configured such that the base film,
whose both end parts have been removed in the removing step, is
coated with the material in the coating step so that surfaces of
respective both edge parts of the base film in the width direction
of the base film are left uncoated as uncoated parts.
[0160] With the configuration, by carrying out edge-uncoated
coating (partial coating) in the coating step in such a manner that
the base film is coated with the material so that each of the
surfaces of respective both edge parts of the base film in the
width direction of the base film are left uncoated as uncoated
parts, it is possible to prevent the material from flowing around
from the both end parts of the base film to a back surface of the
base film, unlike in a case where an entire surface coating is
carried out so that the material is applied to the base film so as
to cover up to the surfaces of the respective both edge parts of
the base film.
[0161] Accordingly, the configuration makes it possible to reduce a
product defect which is caused when the material flows around from
the both end parts of the base film to the back surface of the base
film. In a case where the uncoated parts of the base film are
removed in a step to be carried out later, it is possible to obtain
a separator in which a functional layer has a more uniform film
thickness.
[0162] The method for producing a separator in accordance with
Embodiment 1 is preferably configured such that the removing step
and the coating step are successively carried out with respect to
the base film being transferred.
[0163] With the configuration, the removing step and the coating
step are successively carried out with respect to the base film
being transferred, with no other step carried out between the
removing step and the coating step. Accordingly, after a flare that
occurred at the both end parts has been removed in the removing
step, the coating is carried out with respect to the base film in
the coating step which is subsequent to the removing step.
[0164] With the configuration, therefore, the coating is carried
out with respect to the base film while flatness of the base film
is suitably maintained. This makes it possible to coat the base
film with the material for the functional layer in the coating step
so that the material has a more uniform film thickness.
[0165] A device for producing a separator in accordance with
Embodiment 1 includes: a removing section for removing both end
parts of a base film in a width direction of the base film, the
base film being transferred; and a coating section for coating,
with a material for forming a functional layer, the base film whose
both end parts have been removed by the removing section.
[0166] With the configuration, the both end parts of the base film
are removed by the removing section, before the base film is coated
with the material by the coating section. This makes it possible to
coat the base film with the material in a state in which flares
(sags) that occurred at each of the both end parts of the base film
have been reduced.
[0167] Accordingly, the configuration makes it possible to provide
a device for producing a separator which device is capable of
coating a base film with a material for a functional layer by a
coating section so that the material has a uniform film
thickness.
[0168] The device for producing a separator in accordance with
Embodiment 1 is preferably configured such that the removing
section includes: a first cutting section for cutting off one of
the both end parts of the base film; a second cutting section for
cutting off the other one of the both end parts of the base film;
and a fixing shaft that extends in the width direction of the base
film and fixes the first cutting section and the second cutting
section.
[0169] With the configuration, the first cutting section and the
second cutting section are fixed to the fixing shaft extending in
the width direction of the base film. This allows the first cutting
section and the second cutting section to be more stable as
compared with, for example, a case where the first cutting section
and the second cutting section are fixed to respective different
fixing members.
[0170] Accordingly, the configuration makes it possible for the
first cutting section and the second cutting section to remove the
respective both end parts of the base film at appropriate
positions.
REFERENCE SIGNS LIST
[0171] 1: Lithium-ion secondary battery
[0172] 4: Heat-resistant layer (functional layer)
[0173] 5: Removing device (removing section)
[0174] 7: Coating device (coating section)
[0175] 12: Separator
[0176] 12a: Heat-resistant separator (separator)
[0177] 12b: Heat-resistant separator original sheet (base film)
[0178] 12c: Separator original sheet (base film)
[0179] 12d: Separator original sheet (base film)
[0180] 52: Fixing shaft
[0181] 74: Coating (material)
[0182] e: Both end parts (removal part)
[0183] F: Uncoated part
[0184] S2: Removing step
[0185] S2-2: Second removing step
[0186] S3: Coating step
[0187] S3-2: Second coating step
[0188] S8: Slitting step
* * * * *