KR102116676B1 - Method for Preparing Electrode for Secondary Battery and Device for Manufacturing the Same - Google Patents

Abstract

The present invention is a method of manufacturing an electrode for a secondary battery, (a) a process of forming at least one mixture coating by coating an electrode mixture on one surface of an electrode sheet as a current collector; (b) the process of drying the mixture coating; (c) a process of making the overall coating thickness of the mixture coating part uniform by removing a coating protrusion having a relatively large amount of coating at the coating start site of the mixture coating part; And (d) the process of rolling the mixture coating; provides a method for manufacturing an electrode for a secondary battery, and a manufacturing device accordingly.

Description

Method for manufacturing electrode for secondary battery and manufacturing device {Method for Preparing Electrode for Secondary Battery and Device for Manufacturing the Same}

The present invention relates to a method and an apparatus for manufacturing a secondary battery electrode.

As technology development and demand for mobile devices have increased, demand for batteries as an energy source has rapidly increased, and accordingly, many studies have been conducted on batteries that can meet various demands.

Typically, in the shape of the battery, the demand for a square type secondary battery and a pouch type secondary battery that can be applied to products such as a mobile phone with a thin thickness is high, and in terms of material, it has advantages such as high energy density, discharge voltage, and output stability. There is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries.

The lithium secondary battery consists of a structure in which the electrode assembly of the anode / separator / cathode is embedded in a sealed container with an electrolyte. In general, each electrode mixes an active material and a binder resin component and disperses it in a solvent to make an electrode mixture. After coating this on the surface of the current collector, it is manufactured through a rolling process, a drying process, a slitting process, and a notching process.

In particular, the coating of the electrode mixture may be formed in a pattern in which the elongated electrode sheet is moved in a constant direction, and the electrode mixture coating portion of a relatively large area and the mixture uncoated portion of the relatively small area are repeated. At this time, the uncoated portion of the mixture corresponds to a portion to be cut of the electrode sheet.

On the other hand, in a conventional discharge member such as a die slot, since it is not easy to control the discharge pressure, a thick mixture layer may be formed at the front end of the electrode mixture layer, and the coated electrode mixture is in the form of a fluid slurry. An inclined portion in which the thickness of the mixture layer becomes thinner may be formed at the end of the individual mixture coating portion.

As described above, when the thickness of the mixture coating portion is differently formed at the front end, the center portion, and the end portion, the impregnation rate of the electrolyte solution varies according to each portion of the mixture coating portion, and accordingly, ion conductivity of lithium ions decreases and resistance increases. As a result, a problem occurs in that the charging and discharging efficiency of the secondary battery decreases.

In addition, when each of the mixture coating portions having a non-uniform thickness as described above is manufactured as individual electrodes, a difference in performance or efficiency of the secondary battery occurs, making it difficult to manufacture a secondary battery having uniform quality.

Therefore, in order to improve the charging and discharging efficiency and lifespan characteristics of the secondary battery, there is a need to develop a technique for uniformly forming the thickness of the electrode mixture layer applied on the electrode sheet so that the electrolyte can penetrate uniformly.

The present invention aims to solve the problems of the prior art as described above and the technical problems requested from the past.

The inventors of the present application after repeated in-depth research and various experiments, as described later, by manufacturing and coating the mixture for the secondary battery, after the coating and drying process of the mixture coating part, by removing the coating protrusions with a large amount of coating, the constant Since it is possible to form a thick mixture coating, it is possible to uniformly wet the electrolyte (wetting) in the entire mixture coating, confirming that there is an effect of increasing the capacity and improving the life of the secondary battery, and completing the present invention. I came to Hagi.

In order to achieve this object, the method of manufacturing a secondary battery according to the present invention,

(a) coating the electrode mixture on one surface of the electrode sheet as a current collector to form at least one mixture coating unit;

(b) the process of drying the mixture coating;

(c) a process of making the overall coating thickness of the mixture coating part uniform by removing a coating protrusion having a relatively large amount of coating at the coating start site of the mixture coating part; And

(d) the process of rolling the mixture coating;

As described above, in the method of manufacturing the electrode for a secondary battery according to the present invention, after coating the electrode mixture on the electrode sheet, a physical force is applied to the front end of the electrode mixture coating portion to make the overall coating thickness of the mixture coating portion uniform. Process. That is, the coating protrusions having a relatively large coating amount are removed to form a mixture coating having a uniform thickness, and a problem occurred when a coating protrusion was formed at the end of the mixture coating portion due to fluidity and uneven discharge pressure of the electrode mixture slurry. Can solve it. Specifically, as the electrolyte impregnation rate varies for each part of the mixture coating layer, it is possible to prevent a problem that the ion conductivity is lowered and the efficiency of the secondary battery is lowered.

In addition, since an electrode having a mixture layer having a uniform thickness and size can be manufactured, it is easy to design the overall thickness and capacity of the electrode assembly, and it is possible to provide a secondary battery having uniform quality.

In one specific example, the manufacturing method may be performed in the order of process (a), process (b), process (c), and process (d), and the mixture coating layer in a slurry state before drying has fluidity to form Since the deformation of easily occurs, the removal process of the process (c) in the present invention is more efficient to proceed to the solidified coating mixture layer after the drying process.

In addition, the manufacturing method may be performed in the order of process (a), process (b), process (d), and process (c). According to such a manufacturing method, fine coating protrusions remaining after the rolling process are removed. can do.

In one specific example, after the process (a), process (b), process (c), and process (d) are sequentially performed, process (c) may be performed again. When the removal process is performed twice as described above, since the coating protrusion not removed in the previous removal process can be completely removed, a more uniform electrode can be manufactured.

Meanwhile, the mixture coating part is prepared by applying a paste obtained by mixing the active material of each electrode, a binder, and a conductive agent to an electrode sheet. In the process (a), a plurality of mixture coating parts are predetermined on the moving electrode sheet. The electrode mixture is coated so as to be formed at intervals of, and between the mixture coating parts, an uncoated region where the electrode sheet is exposed to the outside is positioned. The non-coated portion corresponds to a portion to be cut after cutting and drying of the electrode sheet.

In general, since the electrode assembly is manufactured in various sizes according to the size and shape of the outer case and the required capacity in the field to be used, the electrode sheet and the mixture coating part constituting the electrode assembly are cut to a predetermined size in order to meet such needs. It is desirable to further proceed with the process, and thus, after the process (c), the step (e) of cutting the uncoated portion and dividing it into a mixture coating unit may be further included.

At this time, the length of the uncoated portion, which is the separation distance of the mixture coating portions, may range from 5 mm to 100 mm. When the length of the uncoated portion is 5 mm or less, the area of the thick mixture coating portion becomes larger during the rolling process, and as the uncoated portion disappears, the electrode sheet may be difficult to divide, and when the length of the uncoated portion is 100 mm or more, unnecessary It is not preferable because the area of the wasted electrode sheet increases.

The drying in the process (b) is not particularly limited as long as it can quickly remove the solvent mixed in the mixture and does not cause a chemical change in the electrode mixture, preferably hot air drying, or vacuum drying or hot air drying and Vacuum drying can be achieved by mixing. After the drying process, a cooling process at room temperature may be further included to stabilize the electrode mixture.

In one specific example, the process (c) may be performed by various methods to remove the coating protrusion, but most preferably, laser light can be irradiated, and when other removal methods are used Compared to this, it is most preferable because it is possible to precisely control the thickness and remove the coating protrusion while applying only minimal impact to the mixture coating.

In general, in the case of using a laser in the manufacturing process of a secondary battery, it is necessary to prevent as much as possible the thermal damage of the electrode mixture layer in which the electrochemical reaction occurs in direct contact with the electrode sheet and the electrolyte, which is a thin film. Specifically, the quality of the electrode may deteriorate as the periphery of the electrode mixture layer is thermally deformed by the heat of the laser light, and if the deformation by heat continues, the electrode mixture layer decomposes and the function of the electrode may deteriorate. Therefore, it is necessary to find the optimal processing conditions in order to minimize the thermal damage occurring at the laser irradiation site.

As one preferred example, the output wavelength of the laser light may be 1 μm to 12 μm, and in detail, it may be 4 μm to 8 μm. When the output wavelength of the laser light is less than 1 μm, the intensity of the laser light is too strong It becomes undesired because it can damage the solid components of the mixture coating part, and when the output wavelength of the laser light exceeds 12 μm, the intensity of the laser light becomes so weak that the coating protrusions with a large amount of coating cannot be sufficiently removed.

In addition, the output capacity of the laser light may be 1 kW to 15 kW, and specifically 5 kW to 10 kW. The purpose of the laser light used in the present invention is not cutting, but removal of some mixture coating parts, so if the capacity is too large, the object cannot be achieved, and if the output capacity is too small, the cost compared to performance increases to increase the process cost or coating It is not preferable because the protrusion is not easily removed.

After the process (c), the uniform coating thickness may be 10 μm to 100 μm to show the maximum filling density. When the coating thickness becomes thinner than 10 μm, the solid content of active materials and the like becomes too small and the battery It is not preferable because the capacity of may decrease and the impregnation rate of the electrolyte may drop when the coating thickness exceeds 100 μm.

In one specific example, the residue of the coating protrusion removed by the laser becomes an electrode powder and remains on the electrode sheet. In particular, when the removal process is performed once more, the electrode powders scattered by the laser light are Blocking laser light can interfere with the second removal process. In order to prevent such a problem, after the process (c), a process of removing the residue by suction (f) may be further included.

On the other hand, the rolling process of the process (d) reduces the thickness of the electrode sheet and the mixture coating portion after the electrode mixture coating process is completed, thereby increasing the capacity density, and improving the adhesion and adhesion between the electrode sheet and the electrode active material included in the mixture coating portion. In order to increase, it is a process of passing the electrode sheet between two rolling rollers heated to high temperature to compress to a desired thickness and density.

In general, using a double-sided coated electrode rather than a single-sided coated electrode is advantageous in terms of increasing the capacity of the battery. In one specific example, after performing the above processes (a) to (d) on one side of the sheet , It may be performed by repeating the process (a) to (d) for the other surface of the electrode sheet.

The electrode sheet constituting the electrode for a secondary battery according to the present invention is not particularly limited as long as it is a metal having high conductivity without causing a chemical change in the battery. For example, as the positive electrode current collector, stainless steel, aluminum, nickel, titanium, calcined carbon, or a surface treated with carbon, nickel, titanium, silver, etc. on the surface of aluminum or stainless steel may be used, and the negative electrode collector As a whole, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. may be used.

The present invention provides an electrode manufacturing apparatus used in the method for manufacturing an electrode for a secondary battery, wherein the apparatus for manufacturing an electrode for a secondary battery comprises:

A sheet transport unit for moving the electrode sheet at a constant speed;

A coating unit to apply the electrode mixture on the electrode sheet to form a mixture coating;

Drying unit to solidify by removing the solvent contained in the mixture coating;

A coating post-processing part for removing a coating protrusion having a relatively large amount of coating at a coating start site of the mixture coating part; And

A rolling part that presses the mixture coating part from which the coating protrusion is removed;

It may be made of a structure comprising a.

As described above, the apparatus for manufacturing an electrode for a secondary battery according to the present invention moves the electrode sheet located in the sheet conveying part at a constant speed toward a single direction, forms and dries the mixture coating on the electrode sheet, and increases the thickness of the mixture coating. It consists of a structure that presses after removing the coating protrusions for uniformity. Specifically, since the coating amount includes a coating post-processing portion that removes a relatively large amount of coating protrusions, the overall thickness of the mixture coating portion can be uniformly formed. As a result, the electrolyte impregnation rate becomes uniform in the entire portion of the mixture coating portion. It is possible to prevent a decrease in capacity and life.

In one specific example, since the coating post-processing part includes a laser irradiation device, damage to the electrode mixture can be minimized by using a laser irradiation device, and an electrode having a uniform thickness is formed by precisely removing a coating protrusion. It is preferable because it can be done.

In one specific example, the suction part may further include a suction part that sucks and removes the residue of the coating protrusion removed from the coating post-processing part, wherein the suction part is a laser beam of electrode powders scattered by laser light to the coating protrusion. Interception is blocked to prevent interruption of the second removal process. Thus, a more precise removal is possible in the second removal process.

The suction unit may include a vacuum pump or a suction device to suck electrode powders, but the scope of the suction unit is not limited to these.

On the other hand, the present invention also provides a secondary battery including an electrode manufactured by the above method, the secondary battery is not particularly limited in its kind, but as a specific example, high energy density, discharge voltage, output It may be a lithium secondary battery, such as a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery having the advantages such as stability.

In the lithium secondary battery, an electrode for a secondary battery manufactured by the method for manufacturing an electrode for a secondary battery and an electrode assembly including the electrode are sealed inside the battery case together with an electrolyte.

The secondary battery can be used not only for a battery cell used as a power source for a small device, but also a battery pack including a plurality of battery cells used as a power source for a medium to large-sized device requiring high temperature stability, long cycle characteristics, and high rate characteristics. And a unit battery in a medium-to-large-sized device including the battery pack as a power source.

The devices include mobile phones, portable computers, smartphones, tablet PCs, smart pads, netbooks, light electronic vehicles (LEVs), electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrids. Electric vehicles including electric vehicles (Plug-in Hybrid Electric Vehicle, PHEV); Electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters (E-scooters); Electric golf carts; And a power storage system, but is not limited thereto. Since the structure of these devices and their manufacturing method are known in the art, detailed descriptions thereof are omitted herein.

As described above, the manufacturing method and manufacturing apparatus of the electrode for a secondary battery according to the present invention, after coating the electrode mixture on the electrode sheet, by irradiating the laser on a specific condition to the coating protrusion, the mixture coating portion having a uniform thickness as a whole As a result, the electrode is impregnated with an electrolyte so that the lithium ion conductivity can be reduced.

In addition, since the electrode manufactured by such a manufacturing method and a manufacturing apparatus has a constant thickness and size of the electrode mixture layer, it is easy to design the thickness or capacity of the electrode assembly and to provide a secondary battery having uniform performance. have.

1 shows a method of manufacturing an electrode for a secondary battery according to one embodiment of the present invention;
2 shows a method of manufacturing an electrode for a secondary battery according to another embodiment;
3 shows a method of manufacturing an electrode for a secondary battery according to another embodiment;
4 schematically shows the process of making the thickness of the mixture coating on the electrode sheet uniform; And
5 schematically illustrates an apparatus for manufacturing an electrode for a secondary battery according to an embodiment.

Hereinafter, with reference to the drawings according to an embodiment of the present invention, it is for easier understanding of the present invention, and the scope of the present invention is not limited thereto.

1 to 3 schematically illustrate a manufacturing process of an electrode for a secondary battery according to the present invention.

Referring to Figure 1, the method for manufacturing a secondary battery electrode according to the present invention 100 is (a) mixture coating part forming process 110, (b) mixture coating part drying process 120, (c) coating protrusion removal It consists of the process 130 and (d) rolling process 140. Specifically, in step (a) 110, the electrode mixture is coated on one surface of the electrode sheet used as the electrode current collector, and the relatively wide mixture coating portion and the relatively narrow uncoated portion are alternately formed.

(a) When forming the coating portion of the process 110, a mixture in a slurry form is used to facilitate the application process, but it is not easy to control the amount of the mixture to be discharged, so that the thickness of the coating portion is formed non-uniformly. Specifically, a relatively thick coating layer is formed at the beginning of the coating portion, and a relatively thin coating layer is formed at the end of the coating portion. Thereafter, the coating part is solidified through (b) process 120, and the drying process consists of hot air drying and / or vacuum drying. Next, in step (c) (130), the coating protrusions having a non-uniform thickness are removed to form a mixture coating having a uniform overall thickness.

(d) In step 140, a process of rolling the uniformly formed mixture coating is performed. The rolling process may be performed by moving an electrode sheet coated with an electrode mixture between a pair of rolling rolls.

On the other hand, (d) after the process 140 may further include a process (e) (150) for cutting the plain portion and dividing it into a mixture coating unit.

Referring to FIG. 2, a method 200 of manufacturing an electrode for a secondary battery according to the present invention is a case in which (d) rolling process 230 is first performed before (c) coating protrusion removal process 240 is performed. After performing the process of forming and drying the mixture coating part 210 and 220 in the same order as the processes 110 and 120 of (1), (d) pressing the mixture coating part by rolling process 230, and then (c) coating protrusion Through the removal process 240, a mixture coating of uniform thickness is formed. As described above, the electrode manufactured by the manufacturing method according to the present invention can have a more uniform thickness because the fine coating protrusions remaining after pressing can be removed.

On the other hand, (c) after the process 240 may further include a process (e) (250) for cutting the plain portion and dividing it into a mixture coating unit.

Referring to FIG. 3, a method 300 of manufacturing an electrode for a secondary battery according to the present invention includes a process in which a removal residue is sucked, compared with the manufacturing method 100 of FIG. 1, (c) primary Between the coating protrusion removal process 330 and (d) rolling process 350, (f) removal residue suction process 340 is additionally performed, and (d) after rolling process 350, (c) secondary coating. There is a difference in that the process of removing the protrusions 360 is performed.

That is, the manufacturing method 300 may include (f) process 340 to prevent the residue of the coating protrusion removed in (c) process 330 from interfering with the secondary removal process. Thereafter, (d) the rolling process 350 is performed, and (d) the coating protrusion removal process 360 is performed once more in order to further remove the coating protrusions that may remain fine even after the process 350 do. As described above, by performing the removal process of the coating protrusion twice, it is possible to more completely remove the coating protrusion which is not removed in the previous removal process, so that an electrode having a more uniform thickness can be manufactured.

4 is a process for making the thickness of the mixture coating on the electrode sheet uniform, and shows a side cross-sectional view of the electrode sheet 402 and the mixture coating formed on the electrode sheet 402 positioned on the sheet transport unit 401.

Referring to FIG. 4, the electrode sheet 402 is placed on the sheet transport unit 401 moving at a constant speed toward the direction of the arrow, and a plurality of mixture coating units 420 and 430 are formed on the electrode sheet 402. As a result, the mixture coating parts 420 and 430 are formed to be spaced apart at uniform intervals so that the plain part of the predetermined distance D1 is formed. Specifically, the constant distance D1 may be 5 mm to 100 mm, and when considering simplification of the manufacturing process, the distance D1 formed on one electrode sheet may be uniformly formed, but when it is formed non-uniformly Also included in the scope of the present invention.

When forming the electrode mixture coating portion, it is difficult to maintain a constant pressure of the mixture discharge portion, and since a mixture in a fluid slurry state is used, the thickness of the mixture coating layer may be uneven. Specifically, since the front end of the mixture coating portion 420 has a high discharge amount, the thickness of the mixture layer is thickly applied to form a coating protrusion 421. Thus, the coating protrusion 421 can be removed by irradiating laser light 411 having a range of 1 μm to 12 μm using a laser machine 410, so that the overall thickness is A uniform mixture coating part 430 may be manufactured.

5 schematically shows an apparatus for manufacturing a secondary battery electrode according to the present invention.

Referring to FIG. 5, the electrode manufacturing apparatus 500 forms a mixture coating part by applying an electrode mixture on an electrode sheet, and a sheet conveying unit 510 for transferring the electrode sheet at the same speed toward a constant direction in a state where the electrode sheet is positioned at the top. The coating unit 520 to dry and solidify the coating unit 530, the coating post-processing unit 540 for removing the coating protrusion having a relatively large amount of coating at the coating starting portion of the mixture coating unit, and the coating unit by pressing the mixture coating unit It is composed of a rolling unit 550 for increasing the density.

The coating post-processing part 540 may be configured as a laser irradiation device, and thus, a laser light is irradiated to the mixture coating part to remove the coating protrusion, so that the thickness of the mixture coating part is uniformly formed.

As described above, the manufacturing method and manufacturing apparatus of the electrode for a secondary battery according to the present invention, since the electrode mixture coating part undergoes a process of molding to have a constant thickness in all parts, it is possible to manufacture a secondary battery with improved capacity and life of the battery cell. have.

Those of ordinary skill in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above.

Claims (20)

(a) coating the electrode mixture on one surface of the electrode sheet as a current collector to form at least one mixture coating unit;
(b) the process of drying the mixture coating;
(c) a process of making the overall coating thickness of the mixture coating part uniform by removing a coating protrusion having a relatively large amount of coating at the coating start site of the mixture coating part; And
(d) the process of rolling the mixture coating;
Including,
Process (a), process (b), process (d) and process (c) in the order of progress,
In the process (c), the laser light is irradiated to remove the coating protrusion,
The laser light, the output wavelength of 1 μm to 12 μm, the output capacity of the secondary battery electrode manufacturing method characterized in that 1 kW to 15 kW. delete delete delete According to claim 1, In the process (a), the electrode mixture is coated so that a plurality of mixture coating portions are formed at predetermined intervals on the moving electrode sheet, and the electrode sheet is exposed to the outside between the mixture coating portions. Method for manufacturing a secondary battery electrode, characterized in that the non-coated portion is located. [6] The method according to claim 5, further comprising a process (e) of cutting the uncoated portion and dividing it into a mixture coating unit. The method of claim 5, wherein the length of the non-coated portion, which is a separation distance of the mixture coating portions, is in a range of 5 mm to 100 mm. The method of claim 1, wherein the process (b) is performed by hot air and / or vacuum drying. delete delete delete The method of claim 1, wherein the coating thickness is 10 μm to 100 μm. The method of claim 1, further comprising the step (f) of suctioning and removing the residue of the coating protrusion cut by the laser after the step (c). The method of manufacturing an electrode for a secondary battery according to claim 1, wherein steps (a) to (d) are repeatedly performed on the other surface of the electrode sheet. delete delete delete delete delete delete

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