JP2015015147A - Electrode forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode forming apparatus capable of forming an electrode which has the surface of an insulator film having uniform thickness by performing precise patterning.SOLUTION: The electrode forming apparatus includes: an application section (11) that forms an insulator film of the surface of an electrode substrate; and a patterning section (16) that removes a predetermined region of the insulator film. The patterning section (16) includes: a peeling section (13) that peels off the region to be removed from the electrode substrate by irradiating the region to be removed of the film with a laser beam of a first wavelength which transmits the insulator; and a cutting section (15) that cuts the region to be removed of the film from the periphery thereof.

Description

  Embodiments described herein relate generally to an electrode forming apparatus.

  In a Li secondary battery, a porous polymer film (separator) is used as an insulator film for avoiding contact between a positive electrode and a negative electrode. A conventional separator is prepared as a member separate from a positive electrode and a negative electrode, and a battery is manufactured by winding or stacking a laminate in which the separator is sandwiched between the positive electrode and the negative electrode. Since the separator used in this way is a self-supporting film, a certain thickness is required. However, the thickness of the separator leads to restrictions on the number of sheets (or the number of layers), and the capacity of the battery is limited.

  In order to increase the battery capacity by reducing the thickness of the separator, it has been proposed to form the separator directly on the surface of the electrode base material by a coating method. In some cases, the separator on the electrode needs to be patterned. For example, it has been proposed to pattern the separator film by controlling the electric field when the separator film is formed by electrospinning. However, when electric field control is performed, in addition to poor patterning accuracy due to electric field interference, film thickness uniformity is impaired. Specifically, a nanofiber thin film of several μm or less (3 μm in actual measurement) is also formed in a portion where no electric field is applied.

  In order to obtain a Li secondary battery with excellent performance, it is desired that the separator film on the electrode surface be patterned with high accuracy. However, at present, it has not been realized to form a separator film patterned with high precision on the surface of the electrode substrate with a uniform film thickness.

JP 2002-249966 A JP 2006-283241 A

  The problem to be solved by the present invention is to provide an electrode forming apparatus capable of forming an electrode having an insulating film with a uniform film thickness patterned on the surface.

  According to the embodiment, the electrode forming apparatus includes a coating unit that forms an insulator film on the surface of the electrode substrate, and a patterning unit that removes a predetermined region of the insulator film. The patterning unit irradiates a region to be removed of the film with laser light having a first wavelength that passes through the insulator, and removes the region to be removed from the electrode substrate, The to-be-removed area includes a cutting part that cuts from the periphery thereof.

The conceptual diagram showing the structure of the electrode formation apparatus concerning one Embodiment. The schematic diagram which shows the electrode base material in which the insulator film | membrane was formed. Schematic explaining a peeling part. Schematic explaining a cutting part. Schematic which shows an example of the electrode obtained by the formation apparatus of embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating a configuration of an electrode forming apparatus according to an embodiment. The forming apparatus 10 shown in the figure removes a coating portion 11 for forming an insulator film (separator film) on an electrode substrate (not shown) by a coating method and a predetermined region of the insulator film on the electrode substrate. And a patterning unit 16. The patterning unit 16 includes a peeling unit 13 for peeling a predetermined region (scheduled removal region) of the insulator film from the underlying electrode base material, and a cutting unit 15 for cutting the scheduled removal region of the insulator film from the surroundings. In the illustrated electrode forming apparatus 10, the electrode base material is conveyed by a roll-to-roll conveyance mechanism including a conveyance belt 17, an unwinding roll 18, and a winding roll 19. Specifically, the conveyor belt 17 is driven by the unwinding roll 18 and the winding roll 19 to move the electrode base material in the direction of arrow A so as to reach the coating unit 11, the peeling unit 13, and the cutting unit 15 in order. Transport.

  In the patterning part 16, although the peeling part 13 and the cutting part 15 are provided along the moving direction of an electrode base material, it is not limited to this. Contrary to the illustrated example, the patterning unit 16 may be configured by the cutting unit 15 and the peeling unit 13 provided along the moving direction of the electrode substrate.

  In the application part 11, an insulator film 23 is formed on the electrode substrate 21 as shown in FIG. 2. The electrode substrate 21 is a conductive foil having a thickness of about 1 to 200 μm, and the material thereof can be selected from, for example, Al, Au, Ag, Cu, Pt, and conductive stainless steel.

  The insulator film 23 formed on the electrode base material 21 is a structure having substantially no electron conductivity, and may contain either an organic material or an inorganic material. In order to reduce the thickness, it is desirable that the thickness of the insulator film 23 formed on the electrode base material 21 in the apparatus of this embodiment be about 20 μm or less.

  The insulator film containing an organic material is, for example, a fibrous structure, and the material of the fiber can be selected from, for example, polyamideimide (PAI), polyvinylidene fluoride (PVdF), and the like. When such an organic material is used, the insulator film 23 having a thickness of 1 μm or more can be produced.

  The insulator film containing an organic material can be formed by a spinning film forming technique such as electrospinning. Specifically, a spun membrane is formed on the electrode substrate 25 by an electrospinning apparatus that forms fibers by the force of an electric field using a solution in which an organic material as described above is dissolved in an organic solvent as a raw material. The organic solvent can be selected from, for example, dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone, ethanol, methanol, and the like.

  The insulator film 23 containing an inorganic material can be formed by printing a resin containing metal oxide fine particles such as alumina on the electrode substrate 21 by any method such as blade printing or spray coating. it can. When the printing method is employed, for example, the insulator film 23 having a thickness of about 1 to 100 μm can be formed.

  In the peeling unit 13, a predetermined region (scheduled removal region) of the insulator film 23 is irradiated with a peeling laser having a predetermined wavelength, and the insulating film in the planned removal region is peeled from the underlying electrode substrate 21. The peeling part 13 is demonstrated with reference to FIG. As shown in FIG. 3A, the peeling laser beam L <b> 1 is irradiated on the region to be removed of the insulator film 23 formed on the electrode base material 21. As the peeling laser L1, laser light having a wavelength that transmits the insulator film 23 is selected. The energy of the peeling laser beam L <b> 1 that has passed through the insulator film 23 is concentrated at the interface between the insulator film 23 and the electrode substrate 21. As a result, due to the radiant heat from the electrode base material 21, the insulator film 23 a in the removal scheduled region B is peeled off from the electrode base material 21 as shown in FIG.

  The wavelength used for the peeling laser L1 can be appropriately selected according to the material of the insulator film 23. In general, the longer the wavelength of an organic compound, the higher the transmittance. For example, it is known that the light transmittance of a wavelength of 400 nm or less is 10% or less, and the transmittance of light of a wavelength of 800 nm or more is 80% or more. The PAI and PVdF described above have an absorbance of 0.1 or more at a wavelength of 365 nm or less.

  Therefore, for example, in the case of an insulator film including a spun film (organic material) formed by electrospinning, an IR laser having a wavelength of 800 nm or more that easily transmits through the insulator film is used as a peeling laser. More specifically, for example, a semiconductor laser having a wavelength of 1060 nm may be used.

  Thus, it is preferable that the wavelength of the peeling laser applied to the insulator film containing an organic material be 1200 nm or less. When an IR laser is used to peel a predetermined region of the insulator film, it is desirable that the electrode substrate on which the insulator film is formed has a high melting point. For example, the electrode base material 21 which consists of Au, Ag, etc. is mentioned.

  On the other hand, in the case of an insulator film made of an inorganic material, it is preferable to use a UV laser having a wavelength of 380 nm or less as a peeling laser because light having a shorter wavelength has a higher transmittance. In this way, the region to be removed of the insulator film 23 can be peeled off from the electrode substrate 21 by irradiating light with an appropriate wavelength according to the material of the insulator film.

  The direction and angle at the time of irradiating the peeling laser are not particularly limited, and the peeling laser L1 may be irradiated so as to focus on the interface between the electrode substrate 21 and the insulator film 23. The irradiated laser may be either a dot type or a bar type. However, when the peeling laser is irradiated with the bar type, the region to be removed of the insulator film can be more efficiently peeled off.

  When a controller for adjusting the focal point of the peeling laser beam L1 at the interface between the insulator film 23 and the electrode substrate 21 is provided, energy is efficiently concentrated on the interface between the insulator film and the electrode substrate 21. Thus, the region to be removed of the insulator film can be peeled off from the electrode substrate 21.

  The region to be removed of the insulator film 23 peeled off from the electrode base material 21 is cut from the periphery at the cutting portion 15. In the cutting part 15, for example, by applying a guide along the boundary and applying an external force to peel off the planned removal area, a shearing force can be applied to cut the planned removal area from the periphery. When the region to be removed is irradiated with a laser having a wavelength (cutting laser) that is absorbed by the material of the insulator film, it is possible to efficiently perform thermal cutting.

  With reference to FIG. 4, the cutting part 15 using a laser is demonstrated. As shown in FIG. 4A, the cutting laser light L <b> 2 is irradiated on the region to be removed of the insulator film 23 formed on the electrode base material 21. The cutting laser beam L2 has a wavelength that is absorbed by the material of the insulator film 23, and the energy of the laser beam is concentrated on the surface of the insulator film 23. As a result, as shown in FIG. 4B, the planned removal region B of the insulator film 23 is cut and removed from the periphery.

  The operating wavelength of the cutting laser L2 can be appropriately selected according to the material of the insulator film 23. For example, since a spun film made of an organic material formed by electrospinning easily absorbs ultraviolet light having a wavelength of 380 nm or less, it is preferable to use a UV laser. A laser used for cutting an insulator film containing an organic material can be selected from, for example, a KrF laser, a YAG laser, and a third harmonic laser. When a UV laser having a wavelength of 365 nm or less is used, for example, an effect that cutting efficiency is improved can be obtained. On the other hand, in the case of an insulator film made of an inorganic material, it is preferable to use an IR laser of 800 nm or more.

  The direction and angle when irradiating the cutting laser are not particularly limited, and the cutting laser L2 may be irradiated so as to focus on the surface of the insulator film 23. The laser to be irradiated may be either a dot type or a bar type, but when the cutting laser is irradiated in a point type, the region to be removed of the insulator film can be cut with high accuracy.

  By providing a control unit that adjusts the focal point of the laser beam L2 for cutting on the surface of the insulator film 23, energy is efficiently concentrated on the surface of the insulator film 23, so that the region to be removed of the insulator film 23 is removed from the surroundings. Can be cut and removed.

  In any of the peeling portion 13 and the cutting portion 15, it is desirable to adjust the laser output in consideration of the material of the electrode base material 21, the material and thickness of the insulator film 23, and the like. For example, since Au has a higher melting point than Al, when Au is used as the electrode base material 21, the laser output may be increased and the insulator film 23 may be peeled off and cut as compared with the case where Al is used.

  When a metal having a low melting point such as Al or Cu is used as the electrode substrate 21, it is required to adjust and suppress the laser output. If the region to be removed of the insulator film cannot be peeled off or cut even after a single laser irradiation, the object can be achieved by repeating the laser irradiation a plurality of times.

If the output of the peeling laser is at most 1 J / cm ² or less, the region to be removed of the insulator film 23 can be peeled from the electrode substrate 21. Further, if the output of the cutting laser is 1 J / cm ² or less at the maximum, the region to be removed of the insulator film 23 can be cut from the periphery.

  In the electrode forming apparatus of this embodiment, a drying unit (not shown) and a press unit (not shown) can be provided downstream of the application unit 11. In the drying section, the insulator film on the electrode substrate is dried by, for example, warm air or dry air (dry air), and in the press section, the dried insulator film is pressurized by, for example, a roll press. This enhances the stability of the insulator film formed on the electrode substrate.

  The drying unit and the press unit can be provided at any location as long as they are downstream of the application unit 11. For example, when the drying unit is provided after the patterning unit 16, the region to be removed of the insulator film can be removed by peeling / cutting with higher accuracy.

  By using the forming apparatus of this embodiment, a patterned insulator film 23 ′ is obtained on the electrode substrate 21 as shown in FIG. 5. In the present embodiment, the patterned insulator film 23 ′ and the electrode base material 21 are collectively referred to as an electrode 25. As shown in the drawing, in the electrode 25, the insulator film 23 is removed, and the electrode substrate surface 21a is exposed. There is substantially no insulator film on the electrode substrate surface 21a. On the electrode substrate surface 21a, the insulator film is not confirmed by SEM observation, and can be patterned with high accuracy.

  In addition, the uniformity of the film thickness is not impaired in the patterned insulator film 23 '. Specifically, as a result of observation with a laser microscope, it is confirmed that the variation in the film thickness of the patterned insulating film 23 'is within ± 5% with respect to the target film thickness of 10 μm, so that the uniformity is excellent. The

<Example>
Below, the specific example of an electrode formation apparatus is shown.

  Using the electrode forming apparatus of this example, a patterned insulator film is formed on an Al electrode substrate. The used electrode forming apparatus basically has a coating part 11, a peeling part 13, and a cutting part 15, as shown in FIG. As the application unit 11, an electrospinning apparatus that forms fibers by the force of an electric field is used.

  Polyamideimide (PAI) was dissolved in dimethylacetamide (DMAc) at a concentration of 13.13% by mass to prepare an insulator film raw material solution. In the coating part, a spun film is produced on the electrode base material by an electrospinning apparatus using this raw material solution. A film was formed under the spinning conditions of an applied voltage of 40 kV and a liquid supply amount of 1.375 mL / h to form a uniform film (insulator film) on the electrode substrate. The film thickness of the obtained insulator film was 20 μm.

The predetermined region of the insulator film is removed by irradiating the peeling laser at the peeling portion 13 and irradiating the cutting laser at the cutting portion 15. In the peeling part 13, an infrared laser of 1040 nm is used as a peeling laser. This peeling laser was irradiated at 0.2 J / cm ^{2 on the} region to be removed of the insulator film to peel off the underlying electrode substrate.

In the cutting part 15, a 354 nm third harmonic laser was used as a cutting laser. This cutting laser was irradiated to the region to be removed of the insulator film at an output of 0.5 J / cm ² , and was cut and removed from the surroundings.

  In this way, the insulator film was patterned to expose a part of the surface of the electrode substrate, and the electrode 25 as shown in FIG. 5 was obtained. As a result of SEM observation, the presence of the insulator film was not confirmed on the exposed surface 21a of the electrode base material, and was substantially removed. Further, it was confirmed by a laser microscope that the film thickness of the patterned insulator film 23 'was uniform.

  When a Li secondary battery is fabricated using an electrode having an insulator film with poor patterning accuracy or an electrode having an insulator film with a low film thickness uniformity on the surface, the electrode resistance after welding increases. End up. As described above, the electrode formed using the apparatus of the example has an insulator film with a uniform film thickness that is patterned with high precision on the surface. By using such an electrode, a Li secondary battery with reduced electrode resistance after welding is produced.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Electrode forming apparatus; 11 ... Application | coating part; 13 ... Stripping part; 15 ... Cutting part 16 ... Patterning part; 17 ... Conveyance belt; 18 ... Unwinding roll 19 ... Winding roll; 21 ... Electrode base material; Body film L1 ... peeling laser beam; 23a ... peeled insulator film; L2 ... cutting laser beam 23 '... patterned insulator film; 21a ... electrode substrate surface; 25 ... electrode A ... traveling direction; The area to be removed.

Claims (5)

An application part for forming an insulator film on the surface of the electrode substrate; and a patterning part for removing a predetermined region of the insulator film;
The patterning unit includes
Irradiating the region to be removed of the film with a laser beam having a first wavelength that passes through the insulator, and a separation part for separating the region to be removed from the electrode substrate;
An electrode forming apparatus comprising: a region to be removed from the film;   The electrode forming apparatus according to claim 1, wherein the cutting unit includes a laser transmitter that irradiates a laser beam having a second wavelength absorbed by the insulator.   The said peeling part comprises the 1st control part which adjusts the focus of the laser beam of said 1st wavelength to the interface of an insulator film and the said electrode base material. Electrode forming apparatus.   4. The electrode forming apparatus according to claim 2, wherein the cutting unit includes a second control unit that adjusts the focal point of the laser beam having the second wavelength to the surface of the insulator film. 5.   The electrode forming apparatus according to any one of claims 1 to 4, further comprising a roll-to-roll conveyance mechanism that conveys the electrode base material.

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