KR102131212B1 - Method of cutting electrode for secondary battery and lithium battery comprising electrode cut by the same - Google Patents

Abstract

Herein, the step of preparing an electrode laminate comprising a support metal layer and a lithium metal layer provided on at least one surface of the support metal layer; And cutting the electrode laminate by directly irradiating a pulse laser on the lithium metal layer, wherein the lithium metal layer is made of lithium metal having a purity of 95% or more and 100% or less, and a method for cutting the electrode for a secondary battery. Accordingly, the present invention relates to a lithium secondary battery including a cut electrode.

Description

Method for cutting the electrode for a secondary battery and a lithium secondary battery including the electrode cut accordingly {METHOD OF CUTTING ELECTRODE FOR SECONDARY BATTERY AND LITHIUM BATTERY COMPRISING ELECTRODE CUT BY THE SAME}

The present invention relates to a method for cutting an electrode for a secondary battery and a lithium secondary battery including the cut electrode accordingly.

As the demand for mobile technology increases, the demand for secondary batteries as an energy source is rapidly increasing, and accordingly, research on secondary batteries capable of meeting various demands has been conducted. In particular, there is a high demand for lithium secondary batteries having high energy density, discharge voltage and output stability.

In addition, in order to secure advantages in the manufacturing process, the development of a battery that replaces various existing active materials that can be used in a lithium secondary battery and uses lithium metal itself as an electrode is in progress.

Furthermore, in order to manufacture a lithium secondary battery, lithium metal must be cut to a size suitable for the application. However, since lithium has high ductility, various methods have been tried to improve the quality of the foundation.

Conventionally, lithium metal was cut to a suitable size using a mold. However, when the lithium metal is cut using a mold, there is a problem that a protrusion occurs in the lithium electrode or is damaged by bending of the lithium electrode.

In order to solve the above problems, a method of cutting a buffer film on a lithium metal and then using a mold was used. However, even in this case, since the residue of the buffer film is adhered to the lithium metal, an additional process (Roll Press) to remove it is required, and thus, there is an additional problem in that the efficiency in the manufacturing process is reduced.

This specification is intended to provide a method for cutting an electrode for a secondary battery and a secondary battery including the cut electrode accordingly.

An exemplary embodiment of the present invention includes the steps of preparing an electrode laminate including a supporting metal layer and a lithium metal layer provided on at least one surface of the supporting metal layer; Including the step of cutting the electrode stack by directly irradiating a pulse laser on the lithium metal layer; including, wherein the lithium metal layer is made of lithium metal having a purity of 95% or more and 100% or less provides a method for cutting an electrode for a secondary battery do.

In addition, an exemplary embodiment of the present invention provides a secondary battery including an electrode cut according to the method of cutting the electrode for a secondary battery.

According to an exemplary embodiment of the present invention, the cross-section of the electrode is not smoothly cut, and the cross-section of the electrode is increased, thereby solving the problem of forming a burr in the shape of a strip.

According to an exemplary embodiment of the present invention, there is an advantage that solves the problem of bending the metal electrode by mold cutting.

According to an exemplary embodiment of the present invention, since a separate process for removing residues generated on the electrode surface is not required, there is an advantage of simplifying the electrode manufacturing process.

According to an exemplary embodiment of the present invention, there is an advantage in that the electrode cutting process is simplified by directly irradiating a laser without surface treatment through a separate process on the electrode laminate.

1A and 1B are schematic views of an electrode cutting method according to an exemplary embodiment of the present invention.
Figure 2 shows an image taken from the side of the cutting surface of the electrode after cutting according to Examples 1 to 3 and Comparative Example 1.
Figure 3 shows an image taken from the side of the cut surface of the electrode after cutting according to Examples 4 to 6.
Figure 4 shows an image of the cut surface of the electrode after cutting according to Example 7, Example 8, Comparative Example 2 and Comparative Example 3 from the side.
Figure 5 shows an image taken from the side of the cut surface of the electrode after cutting according to Example 9, Example 10, Comparative Example 4 and Comparative Example 5.
Figure 6 shows an image taken from the side of the cut surface of the electrode after cutting according to Examples 9 to 11.
7 shows an image obtained by cutting the cut surface of the electrode after cutting according to Example 9, Example 11, Comparative Example 6, and Comparative Example 7 from the side.
8 shows images taken from the side of the cut surface of the electrode after cutting according to Example 9, Example 12 and Comparative Example 8.
9A shows an image of a projecting portion of an electrode after cutting according to Comparative Example 9.
FIG. 9B shows an image of the X electrode after cutting according to Comparative Example 9.
10A shows an image of an electrode treated with a buffer film before cutting according to Comparative Example 10.
Figure 10b shows an image of the residue of the buffer film formed on the electrode after cutting according to Comparative Example 10.

An exemplary embodiment of the present invention includes the steps of preparing an electrode laminate including a supporting metal layer and a lithium metal layer provided on at least one surface of the supporting metal layer; Including the step of cutting the electrode stack by directly irradiating a pulse laser on the lithium metal layer; including, wherein the lithium metal layer is made of lithium metal having a purity of 95% or more and 100% or less provides a method for cutting an electrode for a secondary battery do.

1A and 2A are schematic views of a method of cutting an electrode for a secondary battery according to an exemplary embodiment of the present invention.

According to FIG. 1A, an exemplary embodiment of the present invention is to prepare an electrode stack 10 including a support metal layer 100 and a lithium metal layer 200 provided on upper and lower surfaces of the support metal layer 100. step; It may include; the step of cutting the electrode stack 10 by directly irradiating the pulse laser 20 to the lithium metal layer 200.

According to FIG. 1B, an exemplary embodiment of the present invention includes the steps of preparing an electrode laminate 11 including a support metal layer 100 and a lithium metal layer 200 provided on an upper surface of the support metal layer 100; It may include; the step of cutting the electrode stack 11 by directly irradiating the pulse laser 20 to the lithium metal layer 200.

According to an exemplary embodiment of the present invention, the lithium metal layer may be provided on at least one surface of the support metal layer. Specifically, the lithium metal layer may be provided on one side and both sides of the support metal layer, more specifically on one side and/or the other side.

According to an exemplary embodiment of the present invention, the electrode laminate may be prepared by purchasing a commercially available electrode laminate or by rolling lithium foil on a supporting metal layer. Specifically, the rolling may mean that the lithium foil formed on the supporting metal layer is compressed by passing a continuous force through a plurality of rotating rolls. More specifically, the rolling may use hot rolling or cold rolling.

In addition, the electrode stack may be prepared by depositing a lithium metal layer on the supporting metal layer using a sputter. Furthermore, the electrode laminate may be prepared by plating the lithium metal on the supporting metal layer.

According to an exemplary embodiment of the present invention, the lithium metal layer may be made of a lithium metal having a purity of 95% or more and 100% or less, and specifically, a purity of 99.8% or more. In addition, the lithium metal layer may be formed of impurities other than the lithium metal and lithium metal. Specifically, the lithium metal layer may include some impurities other than lithium.

According to an exemplary embodiment of the present invention, the electrode cutting method may minimize damage to the electrode by irradiating a laser to the electrode surface of the support metal layer.

Specifically, lithium has a problem in that the electrode cut during physical cutting due to high ductility is warped, a burr occurs, or lithium adheres to the cutting mold. According to the electrode cutting method, the support metal layer Damage to the electrode can be minimized by directly irradiating a laser to the electrode surface.

According to an exemplary embodiment of the present invention, the support metal layer may be used as a current collector of an electrode. Specifically, the current collector may be a path for electrons to move from the electrode.

According to an exemplary embodiment of the present invention, the step of cutting the electrode stack may mean cutting the electrode by irradiating the pulse laser from the light source of the pulse laser located on the top of the electrode. Specifically, cutting the electrode stack may mean cutting the electrode by moving the light source and/or the electrode stack of the pulse laser according to the shape to be cut.

According to an exemplary embodiment of the present invention, the pulse laser may be directly irradiated to the surface of the lithium metal layer of the electrode without applying and coating a separate buffer layer on the electrode surface, thereby simplifying the cutting process.

According to an exemplary embodiment of the present invention, the method for cutting an electrode for a secondary battery may be a method for cutting an electrode for a lithium secondary battery, specifically, a method for cutting a negative electrode for a lithium secondary battery.

In this specification, the pulse laser may mean a laser that is irradiated in a pulse (pulse) form. Specifically, the pulse laser may mean a pulse laser generally known to those skilled in the art, and more specifically, may mean a laser having oscillation and stop of light in time.

According to an exemplary embodiment of the present invention, the support metal layer is copper; Stainless steel; aluminum; nickel; titanium; Calcined carbon; Copper; Stainless steel with carbon, nickel, titanium and silver on the surface; And it may include one or more selected from the group consisting of aluminum-cadmium alloy.

In addition, by forming fine irregularities on the surface of the supporting metal layer, it is possible to enhance the bonding strength with lithium metal, and the supporting metal layer can be used in various forms such as films, sheets, foils, nets, porous bodies, foams, or nonwoven fabrics. have.

According to an exemplary embodiment of the present invention, the thickness of the supporting metal layer may be 1 μm or more and 20 μm or less. Specifically, the thickness of the supporting metal layer may be 1 μm or more and 15 μm or less, or 5 μm or more and 20 μm or less. More specifically, the thickness of the supporting metal layer may be 5 μm or more and 15 μm or less.

It is possible to sufficiently support the active material layer or the like in the above-mentioned thickness, and to have a high electrical conductivity and charging capacity, including a sufficient current collecting material, and to provide an electrode that can be easily processed due to the sufficient thickness.

According to an exemplary embodiment of the present invention, the thickness of the electrode laminate may be 15 μm or more and 160 μm or less. Specifically, the thickness of the electrode laminate may be 15 μm or more and 130 μm or less, or 50 μm or more and 160 μm or less. More specifically, the thickness of the electrode laminate may be 50 μm or more and 130 μm or less. More specifically, the thickness of the electrode laminate may be 50 μm or more and 100 μm or less, or 70 μm or more and 130 μm or less. In addition, the thickness of the electrode laminate may be 70 μm or more and 100 μm or less.

Sufficient durability of the electrode can be secured in the thickness range of the electrode laminate, and due to the sufficiently thin thickness, the electrode can be modified in various forms.

According to an exemplary embodiment of the present invention, the thickness ratio of the lithium metal layer to the support metal layer may be 1:0.1 to 1:14. Specifically, the thickness ratio of the lithium metal layer to the support metal layer may be 1:0.1 to 1:10. In addition, the thickness ratio of the lithium metal layer to the support metal layer may be 1:0.5 to 1:14. More specifically, the thickness ratio of the lithium metal layer to the support metal layer may be 1:0.5 to 1:10. More specifically, the thickness ratio of the lithium metal layer to the support metal layer may be 1:0.5 to 1:5 or 1:1 to 1:10. More specifically, the thickness ratio of the lithium metal layer to the support metal layer may be 1:1 to 1:5.

It is possible to provide an electrode having excellent electrical conductivity in the thickness ratio range and having a large charging capacity.

According to an exemplary embodiment of the present invention, the electrode laminate may further include a protective layer. Specifically, the protective layer may be provided on one surface of the lithium metal layer. More specifically, the protective layer may be provided on at least one surface of the lithium metal layer provided on both sides of the support metal layer.

When the electrode laminate further includes a protective layer, it is possible to solve the problem that the lithium metal layer is easily oxidized due to its high reactivity.

According to an exemplary embodiment of the present invention, the step of cutting the electrode laminate is performed by irradiating a pulse laser directly on the lithium metal layer after removing the protective layer, or irradiating a pulse laser by focusing on the lithium metal layer without removing it. It can be done by.

According to an exemplary embodiment of the present invention, the thickness of the protective layer may be 0.01 μm or more and 20 μm or less. Specifically, the thickness of the protective layer may be 0.01 μm or more and 17 μm or less, or 0.5 μm or more and 20 μm or less. Further, the thickness of the protective layer may be 0.5 μm or more and 17 μm or less. More specifically, the thickness of the protective layer may be 0.5 μm or more and 15 μm or less, or 1 μm or more and 17 μm or less. Further, the thickness of the protective layer may be 1 μm or more and 15 μm or less. More specifically, the thickness of the protective layer may be 1 μm or more and 10 μm or less, or 5 μm or more and 15 μm or less. Further, the thickness of the protective layer may be 5 μm or more and 10 μm or less.

In the thickness range, contamination of the lithium metal layer can be sufficiently prevented, and performance of a secondary battery including the electrode laminate can be realized. Specifically, chemical property changes such as oxidation due to high reactivity of lithium metal in the thickness range, and the lithium metal layer can be sufficiently protected from external physical stimulation, and the residue of the protective layer generated by laser irradiation in the thickness range The cutting quality due to the deterioration can be prevented, and the electron transfer can be smoothly performed in the secondary battery including the electrode stack to secure the performance of the secondary battery.

According to an exemplary embodiment of the present invention, the protective layer is polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVDF) and polyvinylidene fluoride -One or more organic materials selected from the group consisting of hexafluoropropylene (PVDF-HFP) copolymers and/or Li ₃ PO ₄ , Li ₃ N, Li _x La ₁ - _x TiO ₃ (o<x<1), etc. It may include at least one inorganic material selected from the group consisting of oxides and sulfides such as Li ₂ S-GeS-Ga ₂ S ₃ .

According to an exemplary embodiment of the present invention, the pulse width of the pulse laser may be 1ps or more and 100ps or less. Specifically, the pulse width of the pulse laser may be 1ps or more and 50ps or less, or 5ps or more and 100ps or less. Further, the pulse width of the pulse laser may be 5ps or more and 50ps or less. More specifically, the pulse width of the pulse laser may be 7ps or more and 50ps or less, or 5ps or more and 30ps or less. Further, the pulse width of the laser may be 7ps or more and 30ps or less. More specifically, the pulse width of the pulse laser may be 9 ps or more and 30 ps or less, or 7 ps or more and 12 ps or less. Further, the pulse width of the pulse laser may be 9ps or more and 12ps or less.

It is possible to cut the electrode smoothly by minimizing the height of the protrusion in the range of the pulse width. Specifically, the amount of energy and the cutting speed of the laser irradiated in the pulse width range of the pulse laser can be sufficiently secured, and the size of the region affected by heat is minimized in the pulse width range of the pulse laser to minimize the size of the protrusion. Can be reduced.

In the present specification, the pulse width may mean an interval of time at which the amplitude is halved between the rise time and fall time of the pulse.

According to an exemplary embodiment of the present invention, when the pulse width of the pulse laser is 1ps or more and 100ps or less, the output capacity of the pulse laser may be 1W or more and 5W or less. It is possible to make the cutting surface smooth by minimizing the height of the protrusion of the cutting surface in the range of the output capacity. Specifically, the amount of energy of the laser irradiated in the range of the output capacity is sufficient to prevent a problem that the electrode laminate is damaged.

According to an exemplary embodiment of the present invention, when the pulse width of the pulse laser is 1ps or more and 100ps or less, the cutting speed of the pulse laser may be 1mm/s or more and 5mm/s or less. By absorbing a sufficient amount of energy in the range of the cutting speed, it is possible to minimize the height of the protrusion to make the cutting surface smooth. More specifically, it is possible to prevent the peeling problem of the lithium metal layer caused by the excessive amount of energy of the irradiated laser.

In the present specification, the cutting speed may mean a speed at which a light source of the pulse laser moves from one point of the surface of the electrode stack to which the pulse laser is irradiated to another point.

According to an exemplary embodiment of the present invention, when the pulse width of the pulse laser is 1ps or more and 100ps or less, the output wavelength of the pulse laser may be 200nm or more and 1,200nm or less. Specifically, the output wavelength of the pulse laser may be 250 nm or more and 1,200 nm or less, or 200 nm or more and 1,000 nm or less. Further, the output wavelength of the pulse laser may be 250 nm or more and 1,000 nm or less. More specifically, the output wavelength of the pulse laser may be 300 nm or more and 1000 nm or less, or 250 nm or more and 800 nm or less. In addition, the output wavelength of the pulse laser may be 300nm or more and 800nm or less. It is possible to cut the electrode smoothly by minimizing the height of the protrusion in the range of the output wavelength.

According to an exemplary embodiment of the present invention, when the pulse width of the pulse laser is 1ps or more and 100ps or less, the medium of the pulse laser may be ytterbium:yttrium aluminum garnet (Yb:YAG). Specifically, the ytterbium:yttrium aluminum garnet may mean that ytterbium is added to the yttrium aluminum gadget in the form of a cation (Yb ³⁺ ). In addition, the yttrium aluminum garnet may be a complex oxide (Y ₂ Al ₅ O ₁₂ ) of yttrium oxide (Y ₂ O ₃ ) and aluminum oxide (Al ₂ O ₃ ).

According to an exemplary embodiment of the present invention, when the pulse width of the pulse laser is 1ps or more and 100ps or less, the spot size of the pulse laser may be 5 μm or more and 30 μm or less. Specifically, the spot size of the pulse laser may be 5 μm or more and 25 μm or less, or 10 μm or more and 30 μm or less. In addition, the spot size of the pulse laser may be 10 μm or more and 25 μm or less. More specifically, the spot size of the pulse laser may be 10 μm or more and 20 μm or less, or 15 μm or more and 25 μm or less. Further, the spot size of the pulse laser may be 15 μm or more and 20 μm or less. In the range of the spot size, it is possible to minimize the size of the protrusions and improve the cutting quality.

In this specification, the spot size may mean a distance from one end to the other end of one site irradiated with a laser.

According to an exemplary embodiment of the present invention, the pulse width of the pulse laser may be 10 ns or more and 300 ns or less. Specifically, the pulse width of the pulse laser may be 10ns or more and 250ns or less, or 15ns or more and 300ns or less. In addition, the pulse width of the pulse laser may be 15ns or more and 250ns or less. More specifically, the pulse width of the pulse laser may be 15 ns or more and 200 ns or less, or 20 nm or more and 250 nm or less. Further, the pulse width of the pulse laser may be 20 nm or more and 200 ns or less. More specifically, the pulse width of the pulse laser may be 30 nm or more and 150 nm or less, or 35 nm or more and 200 nm or less. Further, the pulse width of the pulse laser may be 35 nm or more and 150 nm or less. Furthermore, the pulse width of the pulse laser may be 35 nm or more and 100 nm or less, 40 nm or more and 150 nm or less, or 40 nm or more and 100 nm or less.

In the range of the width of the pulse laser, laser cutting can be performed to minimize the height of the protrusion. Specifically, a sufficient cutting speed can be secured in the range of the width of the pulse laser, and the size of the protrusion can be reduced as the size of the zone affected by heat is minimized.

According to an exemplary embodiment of the present invention, when the pulse width of the pulse laser is 10ns or more and 300ns or less, the output capacity of the pulse laser may be 10W or more and 50W or less. In the range of the output capacity, it is possible to minimize the height of the protruding portion of the cutting surface so that the cutting surface is smooth and damage to the electrode can be prevented.

According to an exemplary embodiment of the present invention, when the pulse width of the pulse laser is 10ns or more and 300ns or less, the cutting speed of the pulse laser may be 100mm/s or more and 1,000mm/s or less. Specifically, the cutting speed of the pulse laser may be 200 mm/s or more and 1,000 mm/s or less, or 100 mm/s or more and 800 mm/s or less. Further, the cutting speed of the pulse laser may be 200 mm/s or more and 800 mm/s or less. More specifically, the cutting speed of the pulse laser may be 300 mm/s or more and 800 mm/s or less or 200 mm/s or less and 600 mm/s or less. Also, the cutting speed of the pulse laser may be 300 mm/s or more and 600 mm/s or less.

By absorbing a sufficient amount of energy in the range of the cutting speed, it is possible to minimize the height of the protrusion to make the cutting surface smooth. More specifically, it is possible to prevent the peeling problem of the lithium metal layer caused by the excessive amount of energy of the irradiated laser.

According to an exemplary embodiment of the present invention, when the pulse width of the pulse laser is 10ns or more and 300ns or less, the output wavelength of the pulse laser may be 200nm or more and 1,200nm or less. Specifically, the output wavelength of the pulse laser may be 250 nm or more and 1,200 nm or less, or 200 nm or more and 1,000 nm or less. Further, the output wavelength of the pulse laser may be 250 nm or more and 1,000 nm or less. More specifically, the output wavelength of the pulse laser may be 300 nm or more and 1000 nm or less, or 250 nm or more and 800 nm or less. In addition, the output wavelength of the pulse laser may be 300nm or more and 800nm or less. It is possible to cut the electrode smoothly by minimizing the height of the protrusion in the range of the output wavelength.

According to an exemplary embodiment of the present invention, when the pulse width of the pulse laser is 10ns or more and 300ns or less, the medium of the pulse laser may be Yb doped fiber. Specifically, the ytterbium-doped fiber may be in the form of ytterbium added to the optical fiber.

According to an exemplary embodiment of the present invention, when the pulse width of the pulse laser is 10 ns or more and 300 ns or less, the spot size of the pulse laser may be 5 μm or more and 30 μm or less. Specifically, the spot size of the pulse laser may be 5 μm or more and 25 μm or less, or 10 μm or more and 30 μm or less. In addition, the spot size of the pulse laser may be 10 μm or more and 25 μm or less. More specifically, the spot size of the pulse laser may be 10 μm or more and 20 μm or less, or 15 μm or more and 25 μm or less. Further, the spot size of the pulse laser may be 15 μm or more and 20 μm or less. In the range of the spot size, it is possible to minimize the size of the protrusions and improve the cutting quality.

According to an exemplary embodiment of the present invention, an increase rate of the thickness of the electrode laminate after irradiation of the pulse laser with respect to the thickness of the electrode laminate before irradiation of the pulse laser may be 10% or more and 150% or less.

According to an exemplary embodiment of the present invention, the rate of increase in the thickness of the electrode laminate can be calculated by the following equation (1).

[Equation 1]

Increase rate of thickness of electrode stack (%) = {(thickness of electrode stack after irradiation-thickness of electrode stack before irradiation)/(thickness of electrode stack before irradiation)}×100

Another embodiment of the present invention provides a lithium secondary battery including an electrode cut according to the method of cutting the electrode for a secondary battery.

Hereinafter, examples will be described in detail to specifically describe the present invention. However, the embodiments according to the present invention may be modified in various other forms, and the scope of the present invention is not interpreted to be limited to the embodiments described below. The embodiments of the present specification are provided to more fully describe the present invention to those skilled in the art.

Production Example 1 - Preparation of electrode laminate

A lithium metal layer (lithium purity 99.8%), a supporting metal layer containing copper, and a lithium metal layer were sequentially stacked, and the electrode laminate having a thickness of 40 µm and 20 µm, respectively, of the lithium metal layer and the supporting metal layer was 100 mm×50 mm (horizontal) × length).

Example 1

Irradiated to the electrode laminate according to the manufacturing example 1, 20W output capacity, a pulse width of 15ns and a cutting speed of 100mm/s to move the light source (Yb doped fiber) to cut the electrode laminate according to the manufacturing example 1 Did.

Example 2

The electrode laminate was cut in the same manner as in Example 1, except that the output capacity was 30 W.

Example 3

The electrode laminate was cut in the same manner as in Example 1, except that the output capacity was 40 W.

Example 4

The electrode laminate was cut in the same manner as in Example 1, except that the output capacity was 40 W and the pulse width was 45 ns.

Example 5

The electrode laminate was cut in the same manner as in Example 4, except that the pulse width was 120 ns.

Example 6

The electrode laminate was cut in the same manner as in Example 4, except that the pulse width was 220 ns.

Example 7

The electrode laminate was cut in the same manner as in Example 4, except that the cutting speed was set to 300 mm/s.

Example 8

The electrode laminate was cut in the same manner as in Example 4, except that the cutting speed was 600 mm/s.

Example 9

By moving the light source (Yb:YAG disk laser) to the surface of the electrode laminate according to Preparation Example 1, a pulse laser of 2 W output capacity, 10 ps pulse width, 8 μm spot size, and 2 mm/s cutting speed The electrode laminate according to Production Example 1 was cut.

Example 10

The electrode laminate was cut in the same manner as in Example 9, except that the output capacity was 5 W.

Example 11

The electrode laminate was cut in the same manner as in Example 9, except that the cutting speed was 4 mm/s.

Comparative Example 1

The laser was irradiated in the same manner as in Example 1, except that the output capacity was less than 10 W, but the electrode laminate was not cut.

Comparative Example 2

The electrode laminate was cut in the same manner as in Example 4, except that the cutting speed was 50 mm/s.

Comparative Example 3

The laser was irradiated in the same manner as in Example 4, except that the cutting speed exceeded 1,000 mm/s, but the electrode laminate was not cut.

Comparative Example 4

The laser was irradiated in the same manner as in Example 9, except that the output capacity was less than 1 W, but the electrode laminate was not cut.

Comparative Example 5

The electrode laminate was cut in the same manner as in Example 9, except that the output capacity was 10 W.

Comparative Example 6

The electrode laminate was cut in the same manner as in Example 9, except that the cutting speed was 0.5 mm/s.

Comparative Example 7

The laser was irradiated in the same manner as in Example 9, except that the cutting speed was 6 mm/s, but the electrode laminate was not cut.

The conditions of the electrode laminate cutting methods according to Examples 1 to 11 and Comparative Examples 1 to 7 are summarized in Table 1 below.

Output capacity (W) Pulse width Cutting speed Remark Example 1 20 15ns 100mm/s - Example 2 30 15ns 100mm/s - Example 3 40 15ns 100mm/s - Example 4 40 45ns 100mm/s - Example 5 40 120ns 100mm/s - Example 6 40 220ns 100mm/s - Example 7 40 45ns 300mm/s - Example 8 40 45ns 600mm/s - Example 9 2 10ps 2mm/s - Example 10 5 10ps 2mm/s - Example 11 2 10ps 4mm/s - Comparative Example 1 Less than 10 15ns 100mm/s Cannot be cut Comparative Example 2 40 45ns 50mm/s - Comparative Example 3 40 45ns Over 1000 Cannot be cut Comparative Example 4 Less than 1 10ps 2mm/s Cannot be cut Comparative Example 5 10 10ps 2mm/s - Comparative Example 6 2 10ps 0.5mm/s - Comparative Example 7 2 10ps 6mm/s Cannot be cut

The images taken from the side of the cut surface of the electrode laminate cut according to Examples 1 to 11 and Comparative Examples 1 to 7 are shown in FIGS. 2 to 7.

Example 12

The electrode laminate was cut in the same manner as in Example 9, except that the spot size was 19.1 µm.

Comparative Example 8

The electrode laminate was cut in the same manner as in Example 9, except that the spot size was 38.4 µm.

Fig. 8 shows images of the cut surfaces of the electrode laminates according to Example 9, Example 12, and Comparative Example 8 from the side.

Comparative Example 9 -Cutting of the electrode laminate using a mold

The electrode laminate according to Preparation Example 1 was cut using a SUS (Steel Use Stainless) mold.

Comparative Example 10 -Cutting of electrode laminate using mold after buffer film treatment

Before applying the mold, a buffer film of PET material was cut in the same manner as in Comparative Example 9, except that it was attached to the surface of the electrode laminate according to Preparation Example 1.

An image obtained by photographing a protrusion (Burr) of the electrode after cutting according to Comparative Example 9 is shown in FIG. 9A.

After cutting according to the comparative example 9, an image of the 휜 electrode is shown in FIG. 9b.

10A shows an image of an electrode treated with a buffer film before cutting according to Comparative Example 10.

An image of the residue of the buffer film formed on the electrode after cutting according to Comparative Example 10 is shown in FIG. 10B.

<Evaluation>

According to Figure 2, in the case of Examples 1 to 3 in which the output capacity, the pulse width, and the cutting speed are included within a range according to an exemplary embodiment of the present invention, it can be confirmed that the generation of the protrusions and the size thereof are minimized. Comparative Example 1, which falls short of the range according to an exemplary embodiment of the present invention, was confirmed that the electrode laminate was not cut.

According to FIG. 3, it was confirmed that in Examples 4 to 6 in which the pulse width was adjusted to 10 ns or more and 300 ns or less, the size of the protrusions and the size of the protrusions were minimized.

According to FIG. 4, in Examples 7 and 8, in which the cutting speed was 100 mm/s or more and 1,000 mm/s or less, it could be confirmed that the cutting surface was minimized in the formation of the protrusions and the size thereof, but the cutting speed was less than 100 mm/s. In the case of Comparative Example 2, which is 50 mm/s, it was confirmed that the cutting surface was not uniform, and a large number of protrusions having a large size were generated, and when it exceeded 1,000 mm/s, the electrode laminate could not be cut.

According to FIG. 5, in the case of a pulse width of 10 ps, in Examples 9 and 10, in which the output capacity is included in the range according to an exemplary embodiment of the present invention, the cutting surface is even, there are almost no protrusions, and even if it is generated, its size is Although it is minimized, if the output capacity is less than 1 W, the electrode stack cannot be cut, and Comparative Example 5, in which the output capacity exceeds 5 W, produces a large number of protrusions and confirms that the size is larger than the protrusion sizes of Examples 9 and 10. Could.

According to FIG. 6, it was confirmed that in Examples 9 to 11 in which the pulse width was 10 ps, protrusions were hardly generated and had a uniform cut surface.

According to FIG. 7, in Examples 9 and 11 in which the cutting speed was 1 mm/s or more and 5 mm/s or less, almost no protrusion was generated, and it was confirmed that the cutting speed was 0.5 mm/s. In Comparative Example 6, a large number of protrusions having a large size were generated by over-irradiation of a pulsed laser, and Comparative Example 7 in which the cutting speed exceeded 5 mm/s and had a non-uniform cutting surface was confirmed that the electrode laminate was not cut. .

When the contents according to FIGS. 2 to 7 are collectively summarized, according to Comparative Examples 1 to 7, in which the output capacity, pulse width, and cutting speed of the pulse laser are outside a specific range in the present invention, the electrode laminate cannot be cut. Alternatively, even if it was cut, it was confirmed that the cut surface of the cut metal was larger than the size of the cut surface of the cut surface according to Examples 1 to 11, and was not smooth. Therefore, it was confirmed that the electrode for secondary batteries having excellent cutting quality can be cut only when the pulse laser condition of the present invention is satisfied.

In addition, according to FIG. 8, in Example 9 and Example 12 in which a pulse laser having a spot size according to an exemplary embodiment of the present invention was irradiated, the size of the protrusions was 12 μm and 15 μm, respectively, which does not significantly affect the cutting quality. In Comparative Example 8, in which a pulse laser having a spot size exceeding a spot size according to an exemplary embodiment of the present invention was irradiated, it was confirmed that the size of the protrusion was 45 μm, which significantly affected the cutting quality.

9A, when the lithium electrode was cut with a mold, it was confirmed that the protrusions were large enough to be visually confirmed.

In addition, through FIG. 9B, when cutting the lithium electrode with a mold, it was confirmed that the lithium electrode was bent and the lithium electrode was damaged. When the results of FIGS. 7A and 7B are collectively combined, it can be confirmed that cutting with a pulse laser can prevent damage to the shape of the electrode.

Furthermore, through FIGS. 10A and 10B, even if a protective film was formed of a buffer film before cutting a lithium electrode with a mold, it was confirmed that a residue of the buffer film was present after cutting. Through this, it was confirmed that an additional process is required to remove the residue of the buffer film.

10, 11: electrode stack
20: pulse laser
100: support metal layer
200: lithium metal layer

Claims (15)

Preparing an electrode laminate including a support metal layer and a lithium metal layer provided on at least one surface of the support metal layer;
Including the step of cutting the electrode stack by directly irradiating a pulse laser on the lithium metal layer;
The lithium metal layer is made of lithium metal having a purity of 95% or more and 100% or less,
When the pulse width of the pulse laser is 1ps or more and 100ps or less, the output capacity of the pulse laser is 1W or more and 5W or less, the cutting speed of the pulse laser is 1mm/s or more and 5mm/s or less, and the spot size of the pulse laser is 5 μm or more and 30 μm or less,
When the pulse width of the pulse laser is 10ns or more and 300ns or less, the output capacity of the pulse laser is 10W or more and 50W or less, and the cutting speed of the pulse laser is 100mm/s or more and 1,000mm/s or less.
According to claim 1,
The support metal layer is copper; Stainless steel; aluminum; nickel; titanium; Calcined carbon; Copper; Stainless steel with carbon, nickel, titanium and silver on the surface; And an aluminum-cadmium alloy.
According to claim 1,
The thickness of the supporting metal layer is 1 μm or more and 20 μm or less.
According to claim 1,
The electrode laminate has a thickness of 15 μm or more and 160 μm or less.
According to claim 1,
A method of cutting the electrode for a secondary battery, wherein the ratio of the thickness of the lithium metal layer to the support metal layer is 1:0.1 to 1:14.
delete delete According to claim 1,
The pulse width of the pulse laser is 1ps or more and 100ps or less,
The output wavelength of the pulse laser is 200nm or more, 1,200nm or less secondary battery electrode cutting method
delete delete delete According to claim 1,
The pulse width of the pulse laser is 10ns or more and 300ns or less,
The output wavelength of the pulse laser is 200nm or more, 1,200nm or less secondary battery electrode cutting method.
According to claim 1,
The pulse width of the pulse laser is 10ns or more and 300ns or less,
The spot size of the pulse laser is 5㎛ to 30㎛ less method for cutting the electrode for a secondary battery.
According to claim 1,
A method for cutting an electrode for a secondary battery, wherein an increase in the thickness of the electrode laminate after irradiation of the pulse laser with respect to the thickness of the electrode laminate before irradiation of the pulse laser is 10% or more and 150% or less.
A lithium secondary battery comprising an electrode cut according to the method of any one of claims 1 to 5, 8, and 12 to 14.

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