JP2004335374A - Manufacturing method of electrode - Google Patents

Manufacturing method of electrode Download PDF

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Publication number
JP2004335374A
JP2004335374A JP2003132075A JP2003132075A JP2004335374A JP 2004335374 A JP2004335374 A JP 2004335374A JP 2003132075 A JP2003132075 A JP 2003132075A JP 2003132075 A JP2003132075 A JP 2003132075A JP 2004335374 A JP2004335374 A JP 2004335374A
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Japan
Prior art keywords
uncoated
electrode
current collector
active
positive electrode
Prior art date
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Granted
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JP2003132075A
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Japanese (ja)
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JP4238630B2 (en
Inventor
Toru Harada
Mitsuharu Kayano
Toshihide Miyake
Takahiko Yamamoto
利秀 三宅
徹 原田
貴彦 山本
光春 柏野
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Denso Corp
株式会社デンソー
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Priority to JP2003132075A priority Critical patent/JP4238630B2/en
Publication of JP2004335374A publication Critical patent/JP2004335374A/en
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Publication of JP4238630B2 publication Critical patent/JP4238630B2/en
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    • Y02P70/54

Abstract

Provided is a method for manufacturing an electrode that can remove a current collector at low cost without deteriorating battery characteristics.
An electrode manufacturing method according to the present invention is a method for manufacturing an electrode having a mixture layer forming step, a pressing step, and a straightening step, wherein the straightening step heats an uncoated portion by induction heating. The process is characterized in that In the method for manufacturing an electrode according to the present invention, since the uncoated portion is heated by induction heating, the current collector immediately rises to a predetermined temperature. For this reason, the method for manufacturing an electrode of the present invention does not require a large apparatus unlike a conventional heating furnace. In the method for manufacturing an electrode according to the present invention, the current collector is not cut so that the current collector is not damaged. For this reason, the electrode manufactured by the manufacturing method of the present invention is subjected to the curvature correction without deteriorating the battery performance.
[Selection diagram] None

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing an electrode, and more particularly, to a method for manufacturing an electrode having an applied portion on which a mixture layer is formed and an uncoated portion.
[0002]
[Prior art]
2. Description of the Related Art In recent years, lithium batteries are becoming mainstream because of their high weight energy densities as power supplies for electric devices such as mobile phones and portable video cameras. This lithium battery has a positive electrode active material containing lithium and discharges lithium as lithium ions during charging and can occlude lithium ions during discharging. It has a negative electrode active material and stores lithium ions during charging and lithium during discharging. It is composed of a negative electrode capable of releasing ions, and a non-aqueous electrolyte in which an electrolyte composed of a supporting salt containing lithium in an organic solvent is dissolved.
[0003]
Further, in such a lithium battery, in order to improve the weight energy density, the positive electrode and the negative electrode are formed in a sheet shape, and the sheet-shaped positive electrode and the negative electrode are wound or interposed via a separator also formed in the sheet shape. It is stored in a case in a stacked state. The sheet-like positive electrode and negative electrode have a structure in which a mixture layer containing an active material is formed on the surface of a metal foil serving as a current collector.
[0004]
Such a sheet-shaped electrode is prepared by preparing an active material paste in which a positive electrode or a negative electrode active material is dispersed, applying the active material paste to the surface of a current collector, and drying the applied active material paste. It is manufactured by forming a mixture layer and pressing the mixture layer to increase the density of the mixture layer.
[0005]
Usually, the sheet-shaped electrode has an uncoated portion where the current collector on which the mixture layer is not formed is exposed, and the uncoated portion is electrically connected to an external terminal of the battery. The uncoated portion can be manufactured by scraping the mixture layer from the electrode plate.However, due to an increase in the number of manufacturing steps, the active material paste is applied to a portion to be the uncoated portion when the mixture layer is formed. It is formed by not applying.
[0006]
However, when a sheet-like current collector is pressed to increase the density of the mixture layer, the surface of the sheet-like electrode may be wavy, curved, or distorted. When such a phenomenon occurs, when a positive electrode sheet and a negative electrode sheet are spirally wound through a separator sheet to produce an electrode body, sufficient battery output cannot be obtained due to occurrence of winding deviation, or lithium In the case of rechargeable batteries, during repeated charging and discharging, problems such as dendritic deposition of metallic lithium due to concentration of current in the displaced portion of the coated portion where the active material was applied, causing internal short circuit, etc. have occurred. .
[0007]
For this reason, a process using a heating furnace and a tension device is performed as a general strain removing process.
[0008]
However, in the treatment using a heating furnace, since it takes time to raise the temperature of the current collector, the heat efficiency is low and the furnace length is long. As a result, there has been a problem that the physical size of the entire apparatus is increased and the cost is greatly increased.
[0009]
To solve such a problem, it has been devised to process the current collector itself. (See Patent Document 1)
Patent Document 1 discloses that a large number of discontinuous linear cuts are made in the current collector sheet surface before press molding so that the current collector sheet follows the growth of the active material layer during pressing. It is disclosed that a flat sheet-like electrode with little distortion can be manufactured.
[0010]
However, in such a method, the current collector itself is damaged by making a cut. As a result, there has been a problem that the mechanical strength of the current collector is reduced and the durability of the electrode is reduced. Further, there is a problem that the infinite number of cuts lowers the uniformity of the charge / discharge characteristics of the battery.
[0011]
[Patent Document 1]
JP-A-7-192726
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method of manufacturing an electrode that can remove a current collector at low cost without deteriorating battery characteristics.
[0013]
[Means for Solving the Problems]
As a result of repeated studies to solve the above problems, the present inventors have found that the above problems can be solved by causing the uncoated portion of the current collector to generate heat by induction heating.
[0014]
That is, the method for manufacturing an electrode of the present invention comprises: applying an active material paste in which at least an electrode active material is dispersed in a solvent to a part of the surface of the current collector; After forming an uncoated portion where the paste is not applied, a mixture layer forming step of drying the active material paste to form a mixture layer, a pressing step of pressing the mixture layer together with the current collector, and an uncoated portion And a straightening step of correcting the distortion of the electrode, wherein the straightening step is a step of heating the uncoated portion by induction heating.
[0015]
In the method for manufacturing an electrode according to the present invention, the uncoated portion is heated by induction heating. Induction heating is a heating method in which the current collector itself generates heat, and thus the current collector immediately rises to a predetermined temperature. For this reason, the method for manufacturing an electrode of the present invention does not require a large apparatus unlike a conventional heating furnace.
[0016]
In the method for manufacturing an electrode according to the present invention, the current collector is not cut so that the current collector is not damaged. Therefore, the battery performance of the electrode manufactured by the manufacturing method of the present invention is suppressed.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
The method for manufacturing an electrode according to the present invention includes a mixture layer forming step, a pressing step, and a correcting step. A mixture layer is formed in a mixture layer forming step, and the mixture layer is densified in a pressing step. Then, the distortion of the uncoated portion caused by performing the pressing step in the correction step is corrected. Through these steps, a flat electrode can be manufactured.
[0018]
The straightening step is a step of heating an uncoated portion by induction heating. Induction heating is a heating method capable of local heating. The induction heating can locally heat an uncoated portion of the current collector. By raising only the temperature of the uncoated portion, it is possible to prevent the active material in the mixture layer from being thermally damaged.
[0019]
Induction heating is a heating method that causes the current collector to generate heat, and allows the current collector to reach a predetermined temperature in a short time. That is, the heating time can be shortened, and the time required for manufacturing can be shortened.
[0020]
The manufacturing method of the present invention corrects the distortion of the uncoated portion by heating the uncoated portion by induction heating. Therefore, it is not necessary to make a cut in the uncoated portion. As a result, the manufacturing method of the present invention can manufacture an electrode in which a decrease in battery characteristics is suppressed.
[0021]
The heating temperature of the current collector is not particularly limited as long as it can correct the distortion of the uncoated portion. Since it depends on the conditions such as the material of the current collector, it cannot be unconditionally determined.
[0022]
In the production method of the present invention, a heating device for performing induction heating is not particularly limited. That is, it is possible to use a heating device having an induction coil arranged in a state facing the uncoated portion of the current collector.
[0023]
It is preferable to arrange two induction coils in a state of facing each of a pair of opposite surfaces of the uncoated portion. By arranging the induction coil opposite to each of the pair of opposite surfaces of the uncoated portion, magnetic flux can be transmitted from both surfaces of the uncoated portion, and generation of heat generation unevenness can be suppressed. When the heat generation unevenness occurs, it is difficult to eliminate the distortion of the uncoated portion.
[0024]
The straightening step is preferably a step of heating the uncoated portion with tension applied thereto. By heating in a state where tension is applied to the uncoated portion in the straightening step, the elimination of distortion in the uncoated portion is promoted. The method for applying tension to the uncoated portion in the straightening step is not particularly limited. Tension may be applied only to the uncoated portion, or tension may be applied to the uncoated portion via the coating portion.
[0025]
It is preferable that the induction heating concentrates the magnetic flux on the uncoated portion. By concentrating the magnetic flux on the uncoated portion, only the uncoated portion can be heated without causing the coated portion to generate heat. As a result, damage to the mixture layer due to heat generation in the application portion is suppressed, and a decrease in battery performance of the electrode is suppressed. The method for concentrating the magnetic flux on the uncoated portion is not particularly limited. For example, a method of bringing the induction coil close to the uncoated portion or a method of disposing a core made of a soft magnetic material in the induction coil can be used.
[0026]
The current collector is preferably made of a metal foil. When the current collector is made of a metal foil, the size of the current collector itself can be reduced, and the ratio of the mixture layer that causes a battery reaction in the electrodes increases, resulting in a high-performance electrode.
[0027]
After preparing an active material paste in which at least the electrode active material is dispersed in a solvent, and applying the active material paste to both sides of the substantially band-shaped current collector so that both edges in the width direction are uncoated portions, the active material paste is formed. Layer forming step of drying the mixture layer to form a mixture layer, a pressing step of pressing the mixture layer together with the current collector, and a straightening step of heating the uncoated portion by induction heating to correct the distortion of the uncoated portion. And a step. Further, it is preferable that these steps are continuously performed by a device arranged along the flow direction of the substantially belt-shaped current collector. By manufacturing an electrode from a substantially belt-shaped current collector, a high-density wound electrode body can be manufactured.
[0028]
When a substantially band-shaped current collector is used, the tension applied to the uncoated portion in the straightening step is preferably in the length direction of the substantially band. As a method of applying tension in the length direction of the substantially belt-shaped current collector, a tension applying device that applies tension so that the flowing current collector does not sag can be used.
[0029]
The method for producing an electrode of the present invention is particularly effective in producing an electrode used for a wound electrode body in which a sheet-like electrode is wound with a separator interposed therebetween.
[0030]
The electrode manufactured by the electrode manufacturing method of the present invention is not particularly limited as long as it has a structure in which a mixture layer is formed on the surface of a current collector. The production method of the present invention is preferably a method for producing an electrode for a lithium battery.
[0031]
The material of the positive electrode of the lithium battery is not particularly limited as long as it can release lithium ions at the time of charging and occlude at the time of discharging, and can use a material having a known material configuration. In particular, it is preferable to use an active material paste obtained by mixing a positive electrode active material, a conductive material, and a binder applied to a current collector and dried.
[0032]
The positive electrode active material is not particularly limited by the type of the active material, and a known active material can be used. For example, TiS 2, TiS 3, MoS 3, FeS 2, Li (1-x) MnO 2, Li (1-x) Mn 2 O 4, Li (1-x) CoO 2, Li (1-x) NiO 2 , V 2 O 5 and the like. Here, x represents 0 to 1. Further, a mixture of these compounds may be used as the positive electrode active material. Further, a part of the transition metal elements of LiMn 2 O 4 and LiNiO 2 , such as Li 1-x Mn 2 + x O 4 and LiNi 1-x Co x O 2, is at least one or more other transition metal elements or Li May be used as the positive electrode active material.
[0033]
As the positive electrode active material, a composite oxide of lithium and a transition metal such as LiMn 2 O 4 , LiCoO 2 , and LiNiO 2 is more preferable. That is, since the battery has excellent performance as an active material such as excellent diffusion performance of electrons and lithium ions, a battery having high charge / discharge efficiency and good cycle characteristics can be obtained. Further, it is preferable to use LiMn 2 O 4 as the positive electrode active material from the viewpoint of low material cost.
[0034]
The binder has an action of retaining the active material particles. As the binder, an organic binder or an inorganic binder can be used, and examples thereof include compounds such as polyvinylidene fluoride (PVDF), polyvinylidene chloride, and polytetrafluoroethylene (PTFE). Can be.
[0035]
The conductive agent has a function of ensuring the electrical conductivity of the positive electrode. Examples of the conductive agent include one or a mixture of two or more carbon substances such as carbon black, acetylene black, and graphite.
[0036]
Further, as the current collector of the positive electrode, for example, a net, punched metal, foam metal, or a plate-shaped foil of a metal such as aluminum or stainless steel can be used.
[0037]
In manufacturing a positive electrode of a lithium battery, an active material paste is obtained by mixing a positive electrode active material, a conductive material, and a binder with a solvent such as water or an organic solvent.
[0038]
The material of the negative electrode of the lithium battery is not particularly limited as long as it can occlude lithium ions during charging and release lithium ions during discharging, and can use a material having a known material configuration. In particular, it is preferable to use an active material paste obtained by mixing a negative electrode active material and a binder applied to a current collector.
[0039]
The negative electrode active material is not particularly limited, and a known active material can be used. For example, carbon materials such as natural graphite and artificial graphite having high crystallinity, metal materials such as lithium metal, lithium alloy, and tin compound, and conductive polymers can be given.
[0040]
The binder has an action of retaining the active material particles. As the binder, an organic binder or an inorganic binder can be used, and examples thereof include compounds such as polyvinylidene fluoride (PVDF), polyvinylidene chloride, and polytetrafluoroethylene (PTFE). Can be.
[0041]
In manufacturing a negative electrode for a lithium battery, an active material paste is obtained by mixing a negative electrode active material and a binder with a solvent such as water or an organic solvent.
[0042]
As the current collector of the negative electrode, for example, a net, punched metal, foam metal, plate-shaped foil, or the like of copper, nickel, or the like can be used.
[0043]
【Example】
Hereinafter, the present invention will be described using examples.
[0044]
As an example of the present invention, a sheet-shaped positive electrode of a lithium battery was manufactured.
[0045]
(Manufacture of sheet-shaped positive electrode)
First, 85 parts by weight of lithium nickelate as a positive electrode active material, 10 parts by weight of acetylene black as a conductive material, 3 parts by weight of polytetrafluoroethylene (PTFE) as a binder, and 2 parts by weight of carboxymethyl cellulose (CMC) were used. An active material paste was prepared by uniformly dispersing in 100 parts by weight of water.
[0046]
An active material paste is applied on both sides of a current collector made of a hard aluminum foil (AlN30-H18) having a width of 180 mm and a thickness of 15 μm with a coating width of 82 mm (at least 20 mm apart from the widthwise end of the strip-shaped current collector). In this state, the total amount of uncoated portions was 40 mm or more). At this time, an application portion 41 to which the active material paste was applied and an unapplied portion 42 in which the active material paste was not applied to both sides of the application portion 41 and the current collector surface was exposed were formed. The active material paste is applied so that the basis weight per one side after drying is 14.9 mg / cm 2 . Further, the thickness of the active material paste in the application portion after drying was 82.5 μm.
[0047]
Subsequently, the current collector coated with the active material paste was introduced into a drying furnace to dry the active material paste. In the present example, drying was performed by introducing into a hot air drying furnace.
[0048]
Thereafter, the uncoated portion 42 was cut to a width of 100 mm. At this time, cutting was performed so that the widths of the uncoated portions 42 on both sides of the coated portion 41 were 2 mm and 16 mm. Specifically, a 2 mm uncoated portion 42b, a 82 mm coated portion 41, and a 16 mm uncoated portion 42a are arranged in the width direction. The cut and formed current collector was compressed by a roll press so that the total thickness became 76 μm, and then cut to a length of 5.5 m.
[0049]
The cut sheet-shaped positive electrode 4 had a curved shape in which the length of the uncoated portion 42a having a width of 16 mm was significantly shorter than the length of the uncoated portion 42b having a width of 2 mm. Specifically, the uncoated portion 42a was curved such that the central portion in the length direction was at a position separated from the line connecting both ends by 30 mm or more (in the direction of the coated portion 41). In the present embodiment, the vertex of the curvature of the uncoated portion 42a is the central portion of the sheet-like electrode 4, but the electrode can be manufactured by applying the electrode manufacturing method of the present embodiment even if it deviates from the central portion. . The sheet-shaped positive electrode 4 cut out is shown in FIG.
[0050]
The curvature of the sheet-like positive electrode 4 is caused by the difference in width between the uncoated portions 42a and 42b on both sides of the coated portion 41. Specifically, when the mixture layer made of the dried active material paste constituting the application section 41 is compressed together with the current collector, the current collector is pressed together with the mixture layer. At this time, the mixture layer is densified, but the current collector undergoes plastic deformation. The thickness of the current collector becomes thin due to plastic deformation, and the strength and rigidity of the current collector itself decrease.
[0051]
The cut sheet-shaped positive electrode 4 was corrected for distortion at an uncoated portion using a curvature correction device whose configuration is shown in FIG.
[0052]
(Bending straightener)
The curving device 1 for correcting the distortion of the sheet-shaped positive electrode cut out in the embodiment includes an induction heating device 2 and a tension applying device 3.
[0053]
The induction heating device 2 includes a power supply 21 for supplying electric power, a resonance frequency automatic regulator 22 that converts a current from the power supply 21 into an alternating current to generate an induction current, a transformer 23 for adjusting the induction current, And an induction coil 24 to be used. The main circuit configuration of the induction heating device 2 is shown in FIG.
[0054]
The power supply 21 is a device that outputs an input of an AC 200 V AC current as a DC current of a maximum of 300 V DC and 50 A.
[0055]
The automatic resonance frequency adjuster 22 includes an IH inverter unit that converts power supplied from the power supply 21 into an AC current, and an IH inverter unit that changes the frequency of the AC current supplied from the IH inverter unit to a value of 10 kHz or more. And a control unit for controlling the induction current supplied to the heating coil of the heating unit. Further, the control unit performs control such that the current value is minimized.
[0056]
The transformer 23 reduces the voltage of the induced current or increases the voltage to keep the induced current within a predetermined range.
[0057]
The induction coil 24 was formed from a conductive wire. As shown in FIG. 4, the conductive wire constituting the induction coil 24 is disposed so as to sandwich the uncoated portion of the current collector. The induction coil 24 includes a pair of straight portions 241 and 241 arranged to face the uncoated portion of the current collector, and a pair of connecting portions 242 and 242 connecting the pair of straight portions. The induction heating device 2 generates a magnetic flux by causing an induction current to flow through the induction coil 24 to generate heat in an uncoated portion of the current collector facing the induction coil 24. The induction heating device 2 can arbitrarily set the length of the linear portion 241 of the induction coil 24 and the distance from the uncoated portion.
[0058]
In the induction coil 24, a core 25 made of ferrite for concentrating the generated magnetic flux can be provided in the linear portion 241. The core 25 has a substantially concave shape in cross section, and accommodates the linear portion 241 in the notch 251 that is depressed from the surface. Further, in the present embodiment, the core 25 is disposed with the opening surface 25a of the notch 251 facing the uncoated portion, but the surface 25b facing the opening surface 25a faces the uncoated portion. It may be arranged in a state. By arranging the core 25, the magnetic flux generated in the induction coil 24 can be concentrated on the uncoated portion of the current collector opposed thereto, and the energy loss can be suppressed. The configuration when the induction coil 24 has the core 25 is shown in FIG. 5 together with the positive electrode 4 to be heated.
[0059]
The tension applying device 3 includes an unwinding unit 31 that holds a positive electrode roll 4 ′ around which the sheet-shaped positive electrode 4 is wound and supplies the sheet-shaped positive electrode 4, and a sheet in which the distortion of the uncoated portion 42 is corrected. A winding unit 32 for winding the positive electrode 4, a driving roll 33 for extracting the sheet-shaped positive electrode 4 from the unwinding unit 31, and a powder brake 34 for applying a brake to the sheet-shaped positive electrode 4 drawn by the driving roll 33. , Is composed. The tension applying device 3 continuously supplies the sheet-shaped positive electrode 4 to the induction heating device 2. In the tension applying device 3, tension is applied to the sheet-shaped positive electrode 4 by applying a brake to the positive electrode pulled by the driving roll 33 with the powder brake 34.
[0060]
The powder brake 34 can apply a brake by current control, and can set the tension applied to the sheet-shaped positive electrode 4 by changing the current value. In this example, a tension of 90 N was applied. This value is higher than the tension (50 N or more) applied at the time of correcting the distortion by the conventional heating furnace.
[0061]
In the tension applying device 3, the sheet-like positive electrode 4 flows between the units with a horizontal accuracy within ± 10 μm. In this example, the sheet-shaped positive electrode 4 flowed at a flow rate of 10 m / min. This value is faster than the flow velocity (1 m / min or more) that flows when distortion is corrected by the conventional heating furnace.
[0062]
In the present embodiment, the induction heating device 2 is disposed between the powder brake 34 of the tension applying device 3 and the driving roll 33. That is, the tension in the length direction is applied to the sheet-like positive electrode 4 between the powder brake 34 and the driving roll 33, and the uncoated portion 42a is heated by applying the tension to the uncoated portion 42a. To correct the distortion.
[0063]
As an example of the present invention, the sheet-like positive electrodes of Examples 1 to 5 were manufactured by operating the induction heating device 2 under the conditions shown in Table 1.
[0064]
[Table 1]
[0065]
(Example 1)
In the induction heating device 2, the length of the linear portion 241 of the induction coil 24 is 4 m, and the linear portion 241 is disposed at a position 30 mm from the current collector. In addition, a core 25 is provided on the linear portion 241 of the induction coil 24. The distance between the opening surface 25a of the core 25 and the surface of the current collector was 15 mm.
[0066]
With the flow at a flow rate of 10 m / min and a tension of 90 N applied by the driving roll 33, power of 200 V, 30 A, and 33 KHz was supplied to the induction coil 24 to heat the uncoated portion.
[0067]
In this example, the temperature of the uncoated portion was increased to 122 ° C. by induction heating. Further, the distortion amount of the manufactured positive electrode was measured, and the correction amount of the uncoated portion was determined to be 35 mm.
[0068]
(Example 2)
In the induction heating device 2, the length of the linear portion 241 of the induction coil 24 is 4 m, and the linear portion 241 is disposed at a position 40 mm from the current collector. In addition, a core 25 is provided on the linear portion 241 of the induction coil 24. The distance between the opening surface 25a of the core 25 and the surface of the current collector was 25 mm.
[0069]
With the flow at a flow rate of 10 m / min and a tension of 90 N applied by the driving roll 33, power of 200 V, 30 A, and 33 KHz was supplied to the induction coil 24 to heat the uncoated portion.
[0070]
In this example, the temperature of the uncoated portion was increased to 101 ° C. by induction heating. Further, the distortion amount of the manufactured positive electrode was measured, and the correction amount of the uncoated portion was determined to be 25 mm.
[0071]
(Example 3)
In the induction heating device 2, the length of the linear portion 241 of the induction coil 24 is 4 m, and the linear portion 241 is disposed at a position 30 mm from the current collector.
[0072]
With the flow at a flow rate of 10 m / min and a tension of 90 N applied by the driving roll 33, power of 200 V, 30 A, and 33 KHz was supplied to the induction coil 24 to heat the uncoated portion.
[0073]
In this example, the temperature of the uncoated portion was raised to 95 ° C. by induction heating. Further, the distortion amount of the manufactured positive electrode was measured, and the correction amount of the uncoated portion was determined to be 21 mm.
[0074]
(Example 4)
In the induction heating device 2, the length of the linear portion 241 of the induction coil 24 is 2 m, and the linear portion 241 is disposed at a position 30 mm from the current collector. In addition, a core 25 is provided on the linear portion 241 of the induction coil 24. The distance between the opening surface 25a of the core 25 and the surface of the current collector was 15 mm.
[0075]
With the flow at a flow rate of 10 m / min and a tension of 90 N applied by the driving roll 33, power of 200 V, 30 A, and 33 KHz was supplied to the induction coil 24 to heat the uncoated portion.
[0076]
In this example, the temperature of the uncoated portion was increased to 97 ° C. by induction heating. The distortion amount of the manufactured positive electrode was measured, and the correction amount of the uncoated portion was determined to be 23 mm.
[0077]
(Example 5)
In the induction heating device 2, the length of the linear portion 241 of the induction coil 24 is 4 m, and the linear portion 241 is disposed at a position 30 mm from the current collector. In addition, a core 25 is provided on the linear portion 241 of the induction coil 24. The distance between the opening surface 25a of the core 25 and the surface of the current collector was 15 mm.
[0078]
With the flow at a flow rate of 10 m / min and a tension of 90 N applied by the driving roll 33, power of 200 V, 30 A, and 7 KHz was supplied to the induction coil 24 to heat the uncoated portion.
[0079]
In this embodiment, the temperature of the uncoated portion was raised to 80 ° C. by induction heating. Further, the distortion amount of the manufactured positive electrode was measured, and the correction amount of the uncoated portion was determined to be 20 mm.
[0080]
(Comparative Example 1)
In this comparative example, a positive electrode was manufactured in the same manner as in Example 1 except that a hot air generator was installed in the curvature straightening device 1 instead of the induction heating device 2. That is, the uncoated portion was heated by blowing hot air.
[0081]
The hot-air generator raises the temperature of the uncoated portion by blowing hot air of 120 ± 5 ° C. to the uncoated portion from a blowing port opened at a position facing the uncoated portion of the current collector.
[0082]
In this comparative example, the flow rate of the positive electrode was 5 m / min, and the tension applied by the driving roll 33 and the powder brake 34 was 110 N.
[0083]
In this comparative example, it took 48 minutes for the uncoated portion to rise to 121 ° C. by blowing hot air. Further, the distortion amount of the manufactured positive electrode was measured, and the correction amount of the uncoated portion was determined to be 10 mm.
[0084]
(Comparative Example 2)
In this comparative example, a positive electrode was manufactured in the same manner as in Comparative Example 1 except that an infrared irradiator was provided instead of the induction heating device 2 in the straightening device 1. That is, the uncoated portion was heated by irradiating infrared rays.
[0085]
In this comparative example, the flow rate of the positive electrode was 5 m / min, and the tension applied by the driving roll 33 and the powder brake 34 was 110 N.
[0086]
In this comparative example, it took 52 minutes for the uncoated portion to rise to 123 ° C. by the irradiation of infrared rays. Further, the distortion amount of the manufactured positive electrode was measured, and the correction amount of the uncoated portion was determined to be 8 mm.
[0087]
From the above Examples 1 to 5 and Comparative Example, by heating the uncoated portion by induction heating, the temperature of the uncoated portion is quickly raised, so that the distortion can be corrected with a larger correction amount.
[0088]
In each example, the tension applied at the time of heating is smaller than that of the comparative example, and the load applied to the current collector and the mixture layer is smaller. That is, damage to the positive electrode in the process of correcting distortion is reduced, and damage is less likely to occur.
[0089]
In each of the examples, the positive electrode flows at a higher flow rate than the comparative example. That is, by using induction heating to correct the distortion of the uncoated portion, a larger amount of the positive electrode can be processed in a short time. That is, the cost required for manufacturing can be reduced. In addition, the ability to correct distortion in a short time has the effect of reducing the size of the entire curvature correction device.
[0090]
In the above embodiment, a sheet-shaped positive electrode is manufactured, but a sheet-shaped negative electrode can be manufactured similarly.
[0091]
(Production of sheet-shaped negative electrode)
First, 92.5 parts by weight of carbon as a negative electrode active material and 7.5 parts by weight of polyvinylidene fluoride as a binder were uniformly dispersed in 100 parts by weight of water to prepare an active material paste.
[0092]
An active material paste having a coating width of 82 mm is applied to both surfaces of a current collector made of a copper foil having a width of 180 mm and a thickness of 10 μm (at least 20 mm away from an end in the width direction of the belt-shaped current collector. (A total of 40 mm or more). At this time, the current collector had an applied portion on which the active material paste was applied, and an uncoated portion in which the active material paste was not applied on both sides of the applied portion and the current collector surface was exposed. The active material paste is applied so that the basis weight per one side after drying is 14.9 mg / cm 2 . Further, the thickness of the active material paste in the application portion after drying was 82.5 μm.
[0093]
Thereafter, similarly to the above-described positive electrode, the uncoated portion was cut, compressed by a roll press, and then cut to a length of 5.5 m.
[0094]
The cut sheet-shaped negative electrode had a curved shape in which the length of the uncoated portion having a width of 16 mm was significantly shorter than the length of the uncoated portion having a width of 2 mm. Specifically, the uncoated portion having a width of 16 mm was curved such that the central portion in the length direction was at a position separated from the line connecting both ends by 40 mm or more.
[0095]
After that, as in the case of the above-described positive electrode, the distortion was corrected using the bending correction device 1, thereby producing a flat, non-distorted sheet-shaped negative electrode.
[0096]
That is, the curvature straightening device 1 exhibited the same effect as in the case of the sheet-shaped positive electrode in the production of the sheet-shaped negative electrode.
[0097]
(Manufacture of lithium secondary batteries)
The electrode manufactured in the above embodiment can be used for manufacturing a lithium secondary battery. FIG. 6 shows the lithium secondary battery.
[0098]
Between the sheet-shaped positive electrode 4 and the sheet-shaped negative electrode 5, a separator 6 having a thickness of 25 μm, which is cut so as to prevent the positive electrode 4 and the negative electrode 5 from directly contacting each other, is spirally wound. A round electrode body was produced.
[0099]
Subsequently, the leads 43 and 53 attached to the uncoated portions 42 and 52 of the sheet-shaped positive electrode 4 and the sheet-shaped negative electrode 5 are subjected to convergence processing, and are ultrasonically welded to the positive electrode terminal 7 and the negative electrode terminal 8, respectively. After joining by the method, the battery case 9 is housed in the case main body 91 of the battery case 9, and the positive electrode terminal portion 7 and the lid plate 92 and the negative electrode terminal portion 8 and the case main body 91 are welded by a laser welding method so as to maintain airtightness and liquid tightness. Bonded under the conditions.
[0100]
Thereafter, an electrolytic solution was injected into the inside through a liquid inlet 93 opened in the cover plate 92, and sealed with a sealing cover 94.
[0101]
By the above procedure, a lithium secondary battery was manufactured.
[0102]
【The invention's effect】
In the method for manufacturing an electrode according to the present invention, the uncoated portion is heated by induction heating. Induction heating is a heating method in which the current collector itself generates heat, and thus the current collector immediately rises to a predetermined temperature. For this reason, the method for manufacturing an electrode of the present invention does not require a large apparatus unlike a conventional heating furnace.
[0103]
In the method for manufacturing an electrode according to the present invention, the current collector is not cut so that the current collector is not damaged. Therefore, the battery performance of the electrode manufactured by the manufacturing method of the present invention is suppressed.
[Brief description of the drawings]
FIG. 1 is a view showing a sheet-like positive electrode before distortion correction is performed in an example.
FIG. 2 is a diagram illustrating a configuration of a curvature correction device.
FIG. 3 is a diagram showing a circuit configuration of the induction heating device.
FIG. 4 is a diagram showing an induction coil of the induction heating device.
FIG. 5 is a diagram showing an induction coil of an induction heating device having a core.
FIG. 6 is a diagram showing a configuration of a lithium secondary battery.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Curve straightening device 2 ... Induction heating device 21 ... Power supply 22 ... Resonance frequency automatic adjuster 23 ... Transformer 24 ... Induction coil 25 ... Core 3 ... Tension applying device 31 ... Unwinding unit 32 ... Winding unit 33 ... Drive roll 34 ... Positive brake 41 ... Positive electrode 41 ... Coated part 42 ... Uncoated part 43 ... Lead 5 ... Negative electrode 51 ... Coated part 52 ... Uncoated part 53 ... Lead 6 ... Separator 7 ... Positive electrode terminal part 8 ... Negative terminal part 9 ... Case 91 … Case body 92… Lid 93… Injection port 94… Sealing lid

Claims (4)

  1. An active material paste in which at least the electrode active material is dispersed in a solvent is applied to a part of the surface of the current collector, and an applied portion where the active material paste is applied, and an uncoated portion where the active material paste is not applied. After forming, a mixture layer forming step of drying the active material paste to form a mixture layer,
    A pressing step of pressing the mixture layer together with the current collector,
    A straightening step of correcting the distortion of the uncoated portion,
    A method for producing an electrode having
    The method for manufacturing an electrode, wherein the straightening step is a step of heating the uncoated portion by induction heating.
  2. The method for manufacturing an electrode according to claim 1, wherein the straightening step is a step of heating the uncoated portion while applying tension thereto.
  3. The method for manufacturing an electrode according to claim 3, wherein the induction heating concentrates a magnetic flux on the uncoated portion.
  4. The method for manufacturing an electrode according to claim 1, wherein the current collector is made of a metal foil.
JP2003132075A 2003-05-09 2003-05-09 Electrode manufacturing method Expired - Fee Related JP4238630B2 (en)

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007273390A (en) * 2006-03-31 2007-10-18 Denso Corp Manufacturing method of electrode
JP2008235251A (en) * 2007-03-19 2008-10-02 Samsung Sdi Co Ltd Electrode for battery and fabricating method thereof
JP2009176449A (en) * 2008-01-22 2009-08-06 Hitachi Vehicle Energy Ltd Lithium secondary battery
WO2010015908A1 (en) * 2008-08-04 2010-02-11 Nissan Motor Co., Ltd. Method and apparatus for drying electrode material
US20100264133A1 (en) * 2009-04-21 2010-10-21 Dongho Jeong Induction heating device
JP2011040371A (en) * 2009-08-14 2011-02-24 Sb Limotive Co Ltd Electrode plate for secondary battery, and secondary battery including the same
WO2012114905A1 (en) * 2011-02-23 2012-08-30 株式会社 東芝 Nonaqueous-electrolyte secondary battery
WO2012114904A1 (en) * 2011-02-23 2012-08-30 株式会社 東芝 Nonaqueous-electrolyte secondary battery
US8956754B2 (en) 2011-05-11 2015-02-17 Samsung Sdi Co., Ltd. Electrode plate, method for manufacturing the electrode plate, and secondary battery having the electrode plate
DE102017215143A1 (en) * 2017-08-30 2019-02-28 Bayerische Motoren Werke Aktiengesellschaft Electrode and method for the production thereof

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007273390A (en) * 2006-03-31 2007-10-18 Denso Corp Manufacturing method of electrode
JP2008235251A (en) * 2007-03-19 2008-10-02 Samsung Sdi Co Ltd Electrode for battery and fabricating method thereof
JP2009176449A (en) * 2008-01-22 2009-08-06 Hitachi Vehicle Energy Ltd Lithium secondary battery
JP2010040300A (en) * 2008-08-04 2010-02-18 Nissan Motor Co Ltd Method and apparatus for drying electrode material
US20110289790A1 (en) * 2008-08-04 2011-12-01 Nissan Motor Co., Ltd. Method and apparatus for drying electrode material
US9310130B2 (en) 2008-08-04 2016-04-12 Nissan Motor Co., Ltd. Method and apparatus for drying electrode material
WO2010015908A1 (en) * 2008-08-04 2010-02-11 Nissan Motor Co., Ltd. Method and apparatus for drying electrode material
US8461496B2 (en) 2009-04-21 2013-06-11 Samsung Sdi Co., Ltd. Induction heating device for battery electrode
US20100264133A1 (en) * 2009-04-21 2010-10-21 Dongho Jeong Induction heating device
JP2011040371A (en) * 2009-08-14 2011-02-24 Sb Limotive Co Ltd Electrode plate for secondary battery, and secondary battery including the same
WO2012114904A1 (en) * 2011-02-23 2012-08-30 株式会社 東芝 Nonaqueous-electrolyte secondary battery
JP2012174594A (en) * 2011-02-23 2012-09-10 Toshiba Corp Nonaqueous electrolyte secondary battery
JP2012174595A (en) * 2011-02-23 2012-09-10 Toshiba Corp Nonaqueous electrolyte secondary battery
CN103210527A (en) * 2011-02-23 2013-07-17 株式会社东芝 Nonaqueous-electrolyte secondary battery
US9543570B2 (en) 2011-02-23 2017-01-10 Kabushiki Kaisha Toshiba Nonaqueous electrolyte secondary battery
US9142831B2 (en) 2011-02-23 2015-09-22 Kabushiki Kaisha Toshiba Nonaqueous electrolyte secondary battery
WO2012114905A1 (en) * 2011-02-23 2012-08-30 株式会社 東芝 Nonaqueous-electrolyte secondary battery
US8956754B2 (en) 2011-05-11 2015-02-17 Samsung Sdi Co., Ltd. Electrode plate, method for manufacturing the electrode plate, and secondary battery having the electrode plate
DE102017215143A1 (en) * 2017-08-30 2019-02-28 Bayerische Motoren Werke Aktiengesellschaft Electrode and method for the production thereof

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