KR20210066529A - Manufacturing method an anode for lithium metal battery - Google Patents

Abstract

A method for manufacturing a negative electrode for a lithium metal battery according to an embodiment of the present invention includes the steps of: supplying a lithium metal electrode using an unwinder; applying lubricating oil to the surface of the lithium metal electrode; cutting a part to be removed of the lithium metal electrode to form an electrode tab; recovering the lithium metal electrode using a rewinder; and adjusting tension applied to the lithium metal electrode by adjusting the unwinder and the rewinder.

Description

Manufacturing method of a negative electrode for a lithium metal battery {MANUFACTURING METHOD AN ANODE FOR LITHIUM METAL BATTERY}

The present invention relates to a method of manufacturing a negative electrode for a lithium metal battery that can be used in an electrochemical device such as a lithium metal battery.

Recently, interest in energy storage technology is increasing. Efforts for research and development of electrochemical devices are becoming more and more concrete as the field of application is expanding to cell phones, camcorders, notebook PCs, and even the energy of electric vehicles. Electrochemical devices are receiving the most attention in this regard, and among them, the development of rechargeable batteries that can be charged and discharged has become the focus of interest. Recently, in developing such batteries, new electrodes to improve capacity density and specific energy and research and development of battery design.

Among the currently applied secondary batteries, lithium secondary batteries developed in the early 1990s have a higher operating voltage and significantly higher energy density than conventional batteries such as Ni-MH, Ni-Cd, and lead sulfate batteries using aqueous electrolyte solutions. is gaining popularity as

The lithium secondary battery may be typically classified into a lithium metal battery, a lithium ion battery, and a lithium polymer battery. Among them, a lithium metal battery uses lithium metal or a lithium alloy as an anode. Among them, lithium metal has the advantage of obtaining the highest energy density, so continuous research is being conducted.

Here, the lithium secondary battery is manufactured in various sizes in consideration of the field of use, and for this purpose, a process of cutting to a predetermined size is essential.

In addition, a process of notching a continuous electrode sheet at a unit electrode interval is required. In the notching process, a method of notching a portion of the electrode sheet using a punching machine is generally used.

At this time, since lithium metal batteries containing lithium as an anode have good ductility and brittle properties, lithium metal may be smeared on the anode cutting mold or punching machine during the manufacturing process, or residues such as burrs This remains a problem that undermines safety and fairness.

In addition, since the current collector and the lithium metal must be punched at the same time when cutting the negative electrode, the strength of the cutting edge must be considered, and the problem of lithium metal sticking to the cutting edge must also be considered.

In order to solve this problem, a process of cutting with a laser or rolling the surface after cutting has been added. However, laser cutting has a problem of scattering of lithium metal by the laser, and when adding a rolling process, a separate process is added to reduce cost. , there is a problem in terms of time, etc.

On the other hand, in order to increase the energy density of a lithium metal battery, the case of applying lithium metal as a single electrode without a current collector is increasing. However, in this case, a problem such as breakage of the lithium metal in the continuous manufacturing process of the electrode sheet may occur due to the brittle characteristics of the lithium metal.

Embodiments of the present invention are proposed to solve the above problems of the previously proposed methods, and in a method of manufacturing a negative electrode for a lithium metal battery, a problem that occurs as lithium metal has soft ductility is prevented.

However, the problems to be solved by the embodiments of the present invention are not limited to the above problems and may be variously expanded within the scope of the technical idea included in the present invention.

A method of manufacturing a negative electrode for a lithium metal battery according to an embodiment of the present invention includes: supplying a lithium metal electrode using an unwinder; applying lubricating oil to the surface of the lithium metal electrode; cutting a portion to be removed of the lithium metal electrode to form an electrode tab; recovering the lithium metal electrode using a rewinder; and adjusting the tension applied to the lithium metal electrode by adjusting the unwinder and the rewinder.

A tension of 1N to 6N may be applied to the lithium metal electrode.

A plurality of the removal scheduled portions may be positioned spaced apart from each other, and the applying of the lubricant may include intermittently applying the lubricant to a portion of the surface of the lithium metal electrode corresponding to the removal scheduled portion.

The thickness of the lithium metal electrode may be 40 nm to 100 μm.

The lithium metal electrode may move while surrounding at least a portion of one or more guide rollers disposed between the unwinder and the rewinder.

The cutting may include inserting an upper mold corresponding to the removal scheduled portion into a lower mold with the lithium metal electrode interposed therebetween to cut the removal scheduled portion.

The upper mold may include at least one of cemented carbide and cermet.

The strength of the upper mold may be 1500kg / mm ² to about 2500kg / mm ^2.

In the cutting step, as the removal scheduled portion is removed, a plurality of the electrode tabs spaced apart from each other may be formed.

The lubricant is C ₉ H ₂₀ (nonane), C ₁₀ H ₂₂ (decane), C ₁₁ H ₂₂ (undecene), C ₁₁ H ₂₄ (undecane), C ₁₂ H ₂₄ (dodecene), C ₁₂ H ₂₆ (dodecane) , silicone resin, liquid paraffin, fluororesin, and polycarbonate (PC) may include at least one.

The lithium metal electrode may be continuously supplied and recovered by the unwinder and the rewinder.

The method of manufacturing the negative electrode for a lithium metal battery may further include rolling the lithium metal electrode by an upper mill and a lower mill located on the upper and lower portions of the lithium metal electrode, respectively.

The step of applying the lubricant may be performed simultaneously with the step of rolling the lithium metal electrode.

According to the embodiments of the present invention, it is possible to provide a method of manufacturing a negative electrode for a lithium metal battery in which burr generation is suppressed by cutting a lithium metal electrode after applying a lubricant.

In addition, it is possible to prevent the lithium metal electrode from breaking by adjusting the tension applied to the lithium metal electrode in a roll to roll process of continuously manufacturing a negative electrode for a lithium metal battery.

1 is a schematic perspective view for explaining a method of manufacturing a negative electrode for a lithium metal battery according to an embodiment of the present invention.
FIG. 2 is a partial view showing an enlarged portion “A” of FIG. 1 .
3 to 5 are partial views showing a portion “B” of FIG. 1 according to the passage of time, respectively.
6 is a partial view showing an enlarged portion "C" of FIG.
7 is a partial view for explaining that the step of applying the lubricant and the step of rolling the lithium metal electrode are simultaneously performed according to an embodiment of the present invention.
8 is a photograph showing a cut surface of the lithium metal electrode according to Example 1. Referring to FIG.
9 is a photograph showing a cut surface of the lithium metal electrode according to Comparative Example 1.

Hereinafter, with reference to the accompanying drawings, various embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement them. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly explain the present invention, parts irrelevant to the description are omitted, and the same reference numerals are given to the same or similar elements throughout the specification.

In addition, since the size and thickness of each component shown in the drawings are arbitrarily indicated for convenience of description, the present invention is not necessarily limited to the illustrated bar. In order to clearly express various layers and regions in the drawings, the thicknesses are enlarged. And in the drawings, for convenience of description, the thickness of some layers and regions are exaggerated.

Also, when a part of a layer, film, region, plate, etc. is said to be “on” or “on” another part, this includes not only cases where it is “directly on” another part, but also cases where another part is in between. . Conversely, when we say that a part is "just above" another part, we mean that there is no other part in the middle. In addition, to be "on" or "on" the reference part means to be located above or below the reference part, and to necessarily mean to be located "on" or "on" in the direction opposite to the gravitational force. no.

In addition, throughout the specification, when a part "includes" a certain component, this means that other components may be further included rather than excluding other components unless otherwise stated.

In addition, throughout the specification, "planar view" means when the target part is viewed from above, and "cross-sectional view" means when the target part is vertically cut cross-section when viewed from the side.

1 is a schematic perspective view for explaining a method of manufacturing a negative electrode for a lithium metal battery according to an embodiment of the present invention.

Referring to FIG. 1 , the method for manufacturing a negative electrode for a lithium metal battery according to an embodiment of the present invention includes the steps of supplying a lithium metal electrode 100 using an unwinder 200 , the surface of the lithium metal electrode 100 . Applying lubricating oil to the lubricating oil, cutting the planned removal portion of the lithium metal electrode 100 to form an electrode tab, recovering the lithium metal electrode 100 using a rewinder 300 and an unwinder 200 ) and the rewinder 300 to adjust the tension applied to the lithium metal electrode 100 .

Specifically, the lithium metal electrode 100 is unwound by using the unwinder 200 and supplied to the moving path, and then the lithium metal electrode 100 is wound and recovered using the rewinder 300 to recover the lithium metal electrode 100 . ) can be continuously supplied and recovered. That is, the entire process of the manufacturing method of the negative electrode for a lithium metal battery in this embodiment is continuously performed by a roll to roll process.

The roll-to-roll process refers to an apparatus for performing various types of processes on a roll-type film or web.

In order to increase the energy density of the lithium metal battery, lithium metal can be applied to the electrode alone without a current collector. However, the lithium metal of the lithium metal electrode 100 may be broken during the roll-to-roll process due to its unique soft characteristics. can

To prevent this, the unwinder 200 and the rewinder 300 not only supply and recover the lithium metal electrode 100 , but also control the tension applied to the lithium metal electrode 100 . can do.

Specifically, in the present embodiment, a tension of 1N to 6N may be applied to the lithium metal electrode 100 by adjusting the unwinder 200 and the rewinder 300 . The tension applied to the lithium metal electrode 100 by adjusting the interval between the unwinder 200 and the rewinder 300, the position, the diameter, the supply rate of the unwinder 200 and the recovery rate of the rewinder 300, etc. can be maintained at 1N to 6N.

If the tension applied to the lithium metal electrode 100 is less than 1N, sufficient tension is not provided, so it may be difficult to implement a continuous roll-to-roll process. On the other hand, if the tension applied to the lithium metal electrode 100 is more than 6N, the lithium metal electrode 100 may be broken during the roll-to-roll process due to the excessive tension.

That is, when the tension applied to the lithium metal electrode 100 is maintained at 1N to 6N, a continuous roll including a step of applying a lubricant to be described later, a step of cutting the removal scheduled portion, or a step of rolling the lithium metal electrode, etc. The two-roll process can be smoothly performed without breaking the lithium metal electrode 100 .

On the other hand, the lithium metal electrode 100 surrounds at least a portion of one or more guide rollers 500 disposed between the unwinder 200 and the rewinder 300, and can move from the unwinder 200 to the rewinder 300. have.

By disposing the guide roller 500 , the moving lithium metal electrode 100 is prevented from being distorted, and the tension adjusted by the unwinder 200 and the rewinder 300 is uniform for each region of the lithium metal electrode 100 . can be applied

FIG. 2 is a partial view showing an enlarged portion “A” of FIG. 1 in order to explain the step of applying lubricating oil to the surface of the lithium metal electrode 100 .

Referring to FIG. 2 , the method for manufacturing a negative electrode for a lithium metal battery according to the present embodiment includes applying a lubricant 410 to the surface of the lithium metal electrode 100 . 2 is an example thereof, when the lithium metal electrode 100 is moved in a predetermined direction by the unwinder and the rewinder, the lubricant 410 from the application device 400 to the surface of the lithium metal electrode 100. is sprayed, so that the application can be made.

This coating method is an example, and any method available in the art can be used without limitation. For example, it may be applied by a spray method or a dip coating method.

The step of applying the lubricating oil 410 is to prevent lithium metal from oozing out or remaining residues such as burrs in the process of cutting a part of the lithium metal electrode 100, and in FIGS. 3 to 3 to It will be described together with FIG. 5 .

3 to 5 are partial views showing a portion “B” of FIG. 1 according to the passage of time, respectively. In more detail, FIG. 3 is a view showing the upper and lower molds 610 and 620 before cutting the lithium metal electrode 100, and FIG. 4 is the upper and lower molds 610 and 620 of the lithium metal electrode ( 100) is a view showing a state of cutting, and FIG. 5 is a view showing a state in which the upper mold 610 rises after the cutting is completed.

According to the present embodiment, a step of cutting the removal scheduled portion 110 of the lithium metal electrode 100 to form the electrode tab 120 may be followed.

3 and 4 , an upper mold 610 and a lower mold 620 may be disposed above and below the lithium metal electrode 100 moving in a predetermined direction, respectively.

The cutting step includes cutting the removal scheduled portion 110 by inserting the upper mold 610 corresponding to the removal scheduled portion 110 into the lower mold 620 with the lithium metal electrode 100 interposed therebetween. can do.

Although not specifically illustrated, the cutting edge may be positioned along the lower end sides of the upper mold 610 , and the lower mold 620 may have indentations 621 corresponding to the shape of the upper mold 610 . By inserting the upper mold 610 into the indentation 621 with the lithium metal electrode 100 interposed therebetween, the cutting edges of the upper mold 610 cut the planned removal portion 110 of the lithium metal electrode 100. can

Referring to FIG. 5 , it can be seen that the cut upper mold 610 is raised and the electrode tab 120 is formed. That is, the electrode tab 120 is formed on the lithium metal electrode 100 by cutting the removal scheduled portion to provide a kind of notch structure.

In addition, by repeatedly cutting the upper and lower molds 610 and 620 for the lithium metal electrode 100 continuously moving in a predetermined direction, the plurality of electrode tabs 120 are spaced apart from each other at regular intervals. can be formed.

However, since the lithium metal has good ductility and soft properties, the lithium metal electrode 100 is pushed or pulled by the cutting edge of the upper mold 610 in the step of cutting the removal scheduled portion 110 to cause burrs, etc. Residues may cause a problem of sticking to the cutting edge surface.

Also, it may be difficult to form a smooth surface of the cut edge 100a cut in the lithium metal electrode 100 .

The above problems may impair the safety and fairness of the manufacturing process of a negative electrode for a lithium metal battery.

Accordingly, the present invention is to solve the above problems through the step of applying the lubricating oil 410 described above.

In particular, in order to coat the lubricating oil 410 in a wet state on the lithium metal electrode 100 , it is preferable that the removal scheduled portion 110 be cut immediately after the lubricating oil 410 is applied.

When the cutting edge of the upper mold 610 vertically penetrates the lithium metal electrode 100, burrs may occur. When the lubricant 410 is applied to the surface of the lithium metal electrode 100 as in the present invention, the burrs incidence can be reduced. Since the generation of burrs is reduced, the cut edge 100a on which the cut is made may also form a smooth cross-section.

These lubricants 410 include C ₉ H ₂₀ (nonane), C ₁₀ H ₂₂ (decane), C ₁₁ H ₂₂ (undecene), C ₁₁ H ₂₄ (undecane), C ₁₂ H ₂₄ (dodecene), C ₁₂ H ₂₆ (dodecane), silicone resin, liquid paraffin, fluorine resin, and may include at least one of polycarbonate (PC).

Accordingly, the frictional resistance of the surface of the lithium metal electrode 100 is minimized and drying is facilitated, thereby ultimately minimizing damage to the surface of the lithium metal electrode 100 .

On the other hand, the upper mold 610 including the cutting edge may include at least one of a cemented carbide and a cermet for effective cutting of the lithium metal electrode 100, and the strength is 1500 kg/mm ² to based on the Vickers hardness. It can be 2500kg/mm ^{2 .}

Meanwhile, in the continuous roll-to-roll process, a plurality of removal scheduled portions 110 are positioned to be spaced apart from each other to form a plurality of electrode tabs 120 . In this case, the step of applying the lubricant 410 may include intermittently applying the lubricant 410 to a portion of the surface of the lithium metal electrode 100 corresponding to the removal scheduled portion 110 .

That is, for the lithium metal electrode 100 that is continuously supplied and recovered by the unwinder 200 and the rewinder 300 , the lubricant 410 can be applied only to the portion corresponding to the removal scheduled portion 110 . , the lubricant 410 may be intermittently applied. Accordingly, it is possible to reduce the cost of the lubricating oil 410 , and prevent the lubricating oil 410 from being applied to unnecessary parts more than necessary, thereby minimizing the influence of the residual lubricating oil 410 on the lithium metal electrode 100 . .

6 is a partial view showing an enlarged portion “C” of FIG. 1 in order to explain the step of rolling the lithium metal electrode 100 by the upper mill 710 and the lower mill 720 .

Referring to FIG. 6 , in the method of manufacturing a negative electrode for a lithium metal battery according to the present embodiment, an upper mill 710 and a lower mill 720 located on the upper and lower portions of the lithium metal electrode 100, respectively, are the lithium metal electrode 100 . It may include the step of rolling.

The thickness (X) of the raw material of the lithium metal electrode 100 before the rolling is about 400 μm, but after the rolling step, the thickness (Y) of the lithium metal electrode 100 may be 40 nm to 100 μm.

When the tension applied to the lithium metal electrode 100 continuously moving from the unwinder to the rewinder is maintained at 1N to 6N, a continuous roll-to-roll process can be made without the breakage of the lithium metal electrode 100. At this time, 1N to The thickness of the lithium metal electrode 100 to which a tension of 6N is applied may be 40 nm to 100 μm.

7 is a partial view for explaining that the step of applying the lubricant and the step of rolling the lithium metal electrode are simultaneously performed according to an embodiment of the present invention.

Referring to FIG. 7 , in the method of manufacturing the negative electrode for a lithium metal battery according to the present embodiment, the step of applying the lubricant 410 and the step of rolling the lithium metal electrode 100 may be performed simultaneously.

Specifically, when rolling the lithium metal electrode 100 moving in a predetermined direction in which the upper mill 710 and the lower mill 720 respectively located on the upper and lower portions of the lithium metal electrode 100 are rolled, the coating device 400a) may spray the lubricant 410 to each of the upper mill 710 and the lower mill 720 . Accordingly, at the same time that the lithium metal electrode 100 is rolled, the lubricant 410 may be applied to the surface of the lithium metal electrode 100 .

The lubricant 410 can reduce the generation of burrs in the step of cutting the removal scheduled portion, which can be performed later, and can prevent the formation of cracks or the like during the rolling process of the lithium metal electrode 100 .

Specifically, there is a risk that cracks may be formed on the surface of the lithium metal electrode 100 due to the frictional force applied in inducing the forced rolling of the lithium metal electrode 100 through the upper mill 710 and the lower mill 720. . Therefore, in this embodiment, by spraying the lubricant 410 on the surfaces of the upper mill 710 and the lower mill 720, the frictional force is reduced as a kind of buffering action to prevent crack formation, while naturally lubricating oil on the surface of the lithium metal electrode 100 ( 410) can be applied.

Hereinafter, examples will be given to describe the present invention in detail. However, the embodiment according to the present invention may be modified in various other forms, and the scope of the present invention should not be construed as being limited to the embodiment described in detail below. The embodiments of the present invention are provided to more completely explain the present invention to those of ordinary skill in the art.

Example 1

After the lithium metal electrode was interposed in the roll-to-roll facility, ^{1 mg/mm 2} _{of C 12} H ₂₆ (dodecane), a lubricant, was applied to the surface by a spray method.

Thereafter, the lithium metal electrode coated with the lubricant was cut using a cutting blade.

At this time, the roll-to-roll process speed was 10 m / min, the material of the cutting edge was a cemented carbide, and the strength of the cemented carbide was 10 Mpa / m ^0.5 . In addition, the tension applied to the lithium metal electrode was controlled to 4N by adjusting the gap, position, diameter, and difference between the supply rate of the unwinder and the recovery rate of the rewinder between the unwinder and the rewinder.

Comparative Example 1

A negative electrode for a lithium metal battery was prepared in the same manner as in Example 1, except that lubricant was not applied.

Evaluation Example 1: Burr thickness measurement method

In Example 1 and Comparative Example 1, the burr thickness was measured by scanning the cutting section using a 3D optical microscope (manufactured by Bruker, Contour Elite K).

The burr thickness measurement results according to Example 1 and Comparative Example 1 are shown in Table 1, and cut surfaces of the lithium metal electrodes according to Example 1 and Comparative Example 1 are shown in FIGS. 8 and 9, respectively.

number of times Average (μm) standard deviation (μm) Capability
(average-min)/3 sigma Example 1 7 20.14 6.31 1.42 Comparative Example 1 11 46.5 13.6 0.52

Referring to Table 1, in the case of Example 1 to which the lubricant was applied, the average burr thickness was 20.14 μm, and it was confirmed that the generation of burrs was reduced compared to Comparative Example 1.

In addition, referring to FIGS. 8 and 9 , it was confirmed that the cut surface of Example 1 had fewer burrs than the cut surface of Comparative Example 1, thereby forming a smooth surface.

Evaluation Example 2: Adjustment of tension according to the thickness of the lithium metal electrode

Table 2 shows the tension at which break occurs depending on the thickness of the lithium metal electrode interposed in the roll-to-roll facility.

Thickness of lithium metal electrode Uninterrupted tension (N) Tension caused by breakage (N) 40μm 1.1 1.3 80μm 2.4 3.0

Referring to Table 2, when the tension applied to the lithium metal electrode is adjusted to 1.1N for the lithium metal electrode of 40 μm, the supply and recovery of the lithium metal electrode in the roll-to-roll facility is smoothly performed, but the applied tension is 1.3N. It was confirmed that breakage occurred in the lithium metal electrode.

Next, when the tension applied to the lithium metal electrode is adjusted to 2.4N with respect to the lithium metal electrode of 80 μm, the supply and recovery of the lithium metal electrode within the roll-to-roll facility is smoothly performed, but when the applied tension becomes 3.0N, lithium metal It was confirmed that breakage occurred in the electrode.

Although the preferred embodiment of the present invention has been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention defined in the following claims are also present is within the scope of the

100: lithium metal electrode
200: unwinder
300: rewinder
400: applicator
410: lubricant
500: guide roller
610: upper mold
620: lower mold
710: upper mill
720: lower mill

Claims (13)

supplying a lithium metal electrode using an unwinder;
applying lubricating oil to the surface of the lithium metal electrode;
cutting a portion to be removed of the lithium metal electrode to form an electrode tab;
recovering the lithium metal electrode using a rewinder; and
and adjusting the tension applied to the lithium metal electrode by adjusting the unwinder and the rewinder. In claim 1,
A method of manufacturing a negative electrode for a lithium metal battery in which a tension of 1N to 6N is applied to the lithium metal electrode. In claim 1,
A plurality of the removal scheduled parts are located spaced apart from each other,
The applying of the lubricant may include intermittently applying the lubricant to a portion of the surface of the lithium metal electrode corresponding to the removal scheduled portion. In claim 1,
The thickness of the lithium metal electrode is 40nm to 100㎛ method of manufacturing a negative electrode for a lithium metal battery. In claim 1,
The lithium metal electrode is a method of manufacturing a negative electrode for a lithium metal battery that moves while surrounding at least a portion of one or more guide rollers disposed between the unwinder and the rewinder. In claim 1,
The cutting step includes inserting the upper mold corresponding to the removal scheduled portion into the lower mold with the lithium metal electrode interposed therebetween to cut the removal scheduled portion. In claim 6,
The upper mold is a method of manufacturing a lithium metal battery negative electrode comprising at least one of a cemented carbide and a cermet (cermet). In claim 6,
The strength of the upper mold is 1500kg/mm ² to 2500kg/mm ^{2 A} method of manufacturing a negative electrode for a lithium metal battery. In claim 1,
In the cutting step, as the removal scheduled portion is removed, a plurality of the electrode tabs spaced apart from each other are formed. In claim 1,
The lubricant is C ₉ H ₂₀ (nonane), C ₁₀ H ₂₂ (decane), C ₁₁ H ₂₂ (undecene), C ₁₁ H ₂₄ (undecane), C ₁₂ H ₂₄ (dodecene), C ₁₂ H ₂₆ (dodecane) , A method of manufacturing a lithium metal battery negative electrode comprising at least one of silicone resin, liquid paraffin, fluorine resin, and polycarbonate (PC). In claim 1,
A method of manufacturing a negative electrode for a lithium metal battery in which the lithium metal electrode is continuously supplied and recovered by the unwinder and the rewinder. In claim 1,
The method of manufacturing a negative electrode for a lithium metal battery further comprising the step of rolling the lithium metal electrode by an upper mill and a lower mill located on each of the upper and lower portions of the lithium metal electrode. In claim 12,
The step of applying the lubricating oil is a method of manufacturing a negative electrode for a lithium metal battery made simultaneously with the step of rolling the lithium metal electrode.

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