KR20170100377A - Method for Preparing Electrode for Secondary Battery and Device for Manufacturing the Same - Google Patents

Abstract

The present invention, as a method for preparing an electrode for a secondary battery, provides a method for preparing an electrode for a secondary battery, and a preparing device thereby, wherein the method comprises the steps: (a) coating an electrode mixture on one surface of an electrode sheet which is a current collector to form at least one mixture coating portion; (b) drying a mixed coating portion; (c) re d (d) rolling the mixed coating portion. According to the method and device for manufacturing an electrode for a secondary battery according to the present invention, the mixed coating portion having the uniform thickness is formed to make an electrolyte impregnation rate of the electrode uniform, thereby preventing the lithium ion conductivity from decreasing.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing an electrode for a secondary battery,

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

As technology development and demand for mobile devices have increased, there has been a rapid increase in demand for batteries as an energy source, and accordingly, a lot of researches on batteries that can meet various demands have been conducted.

Typically, in terms of the shape of a battery, there is a high demand for a prismatic secondary battery and a pouch-type secondary battery which can be applied to products such as mobile phones with a small thickness, and has advantages such as high energy density, discharge voltage, There is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries.

The lithium secondary battery has a structure in which an electrode assembly of a positive electrode / separator / negative electrode is embedded in a closed container together with an electrolyte. In general, each electrode is prepared by dispersing an active material and a binder resin component in a solvent to form an electrode mixture , And then coating the surface of the current collector with a roll process, a drying process, a slitting process, and a notching process.

Particularly, the coating of the electrode mixture may be performed by repeating a process of moving the elongated electrode sheet in a predetermined direction and repeating a relatively wide area of the electrode compound coating portion and a relatively narrow area of the non-coating portion. In this case, the uncoated portion corresponds to a cut-off portion of the electrode sheet.

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

As described above, if the thickness of the compound coating portion is differently formed at the front end portion, the center portion, and the end portion, the electrolyte impregnation rate becomes uneven according to each portion of the compound coating portion. As a result, As a result, the charging / discharging efficiency of the secondary battery decreases.

In addition, when each of the uncoated coating portions having uneven thicknesses as described above is manufactured as individual electrodes, there is a difference in performance or efficiency of the secondary battery, making it difficult to manufacture a secondary battery having uniform quality.

Therefore, in order to improve the charging / discharging efficiency and lifetime characteristics of the secondary battery, it is necessary to develop a technique for uniformly forming the thickness of the electrode mixture layer coated on the electrode sheet so that the electrolyte can uniformly permeate.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments. As a result, it has been found that, when manufacturing an electrode for a secondary battery, after coating and drying of a compound coating portion, coating protrusions having a large coating amount are removed, (Wetting) can be uniformly performed in the whole compound coating portion, and it is confirmed that the capacity and life of the secondary battery are increased. As a result, the present invention has been completed It came to the following.

In order to accomplish the above object, the present invention provides a method of manufacturing a secondary battery,

(a) coating an electrode mixture on one surface of a current collector sheet to form at least one composite coating portion;

(b) drying the mixed coating portion;

(c) removing coating protrusions having a relatively large coating amount at the coating start portion of the composite coating portion, thereby making the overall coating thickness of the coating portion uniform; And

(d) rolling the composite coating portion.

As described above, in the method of manufacturing an electrode for a secondary battery according to the present invention, an electrode mixture is coated on an electrode sheet, and a physical force is applied to the front end of the electrode mixture coating portion to uniformize the overall coating thickness of the mixture coating portion ≪ / RTI > That is, the coating protrusions having a relatively large coating amount are removed to form a uniform coating portion having a uniform thickness. In the prior art, due to the fluidity of the electrode slurry and uneven discharge pressure, problems Can be solved. Specifically, the ion conductivity is lowered as the electrolyte solution impregnation rate is varied for each portion of the composite coating layer, and the problem of deterioration of the efficiency of the secondary battery can be prevented.

In addition, it is possible to manufacture an electrode in which a mixed layer having uniform thickness and size is formed. Therefore, the overall thickness and capacity of the electrode assembly can be easily designed, and a secondary battery having uniform quality can be provided.

In one specific example, the process may be carried out in the order of steps (a), (b), (c) and (d) The removal process of the process (c) of the present invention is more efficient to proceed to the solidified coating material layer after the drying process.

In addition, the manufacturing method may be performed in the order of steps (a), (b), (d) and (c). According to this manufacturing method, the remaining fine coating protrusions can do.

In one specific example, the manufacturing method may proceed to step (c) again after the steps (a), (b), (c), and (d) are sequentially performed. When the removal process is performed twice as described above, it is possible to completely remove the coating protrusion which has not been removed in the conventional removal process, so that a more uniform electrode can be manufactured.

Meanwhile, the composite coating portion is manufactured by coating the electrode sheet with a paste obtained by mixing an active material of each electrode, a binder and a conductive agent. In the step (a), a plurality of composite coating portions are formed on a moving electrode sheet And an unoccupied portion where the electrode sheet is exposed to the outside is positioned between the mixture coating portions. The unprinted portion corresponds to a cut-off portion where cutting is performed after the electrode sheet is rolled and dried.

Generally, the electrode assembly is manufactured in various sizes depending on the size and shape of the outer case and the capacity required in the field to be used. Therefore, in order to meet such a demand, the electrode sheet and the composite coating portion constituting the electrode assembly are cut (C), it is possible to further include a step (e) of cutting the uncoated portion and dividing the uncoated portion into units of the coated coating portion.

At this time, the length of the uncoated portion, which is the separation distance of the compound coating portions, may be in the range of 5 mm to 100 mm. When the length of the non-coated portion is 5 mm or less, the area of the thick composite coating portion is widened during the rolling process, so that the separation of the electrode sheet may be difficult as the non-coated portion disappears. The area of the electrode sheet to be wasted increases, which is not preferable.

Drying in the above step (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, the drying is performed by hot air drying or vacuum drying or hot air drying, Followed by vacuum drying. After the drying process, a cooling process at room temperature may be further performed to stabilize the electrode mixture.

In one specific example, the step (c) may be performed by various methods to remove the coating protrusion, but most preferably, the laser light can be irradiated. In the case of using another removing method It is most preferable because it is possible to adjust the thickness precisely and remove the coating protrusion while applying only a minimum impact to the composite coating portion.

Generally, when a laser is used in the manufacturing process of a secondary battery, it is necessary to prevent thermal damage of the electrode mixture layer, which is directly contacted with the thin electrode sheet and the electrolyte, to cause an electrochemical reaction. Specifically, the peripheral portion of the electrode mixture layer may be thermally deformed due to the heat of the laser beam, thereby deteriorating the quality of the electrode. If deformation due to heat is continued, the function of the electrode may be degraded while decomposing the electrode mixture layer. Therefore, it is necessary to find the optimum processing condition in order to minimize the heat damage generated at the laser irradiation site.

As one preferred example, the output wavelength of the laser beam may be 1 to 12 μm, more specifically 4 to 8 μm. When the output wavelength of the laser beam is less than 1 μm, the intensity of the laser beam is too strong If the output wavelength of the laser beam exceeds 12 μm, the intensity of the laser beam becomes too weak to sufficiently remove the coating protrusions having a large coating amount, which is undesirable.

Also, the output capacity of the laser beam may be 1 kW to 15 kW, and more specifically 5 kW to 10 kW. Since the purpose of the laser light used in the present invention is not cutting but removal of a part of the coating part, if the capacity is too large, the object can not be achieved. If the output capacity is too small, It is not easy to remove the protruding portion.

When the thickness of the coating is reduced to less than 10 탆, the solid content of the active material becomes too small, and the thickness of the battery becomes too small, And the coating thickness exceeding 100 탆 is not preferable because the impregnation rate of the electrolyte may be lowered.

In one specific example, the remainder of the coating protrusion removed by the laser becomes electrode powder and remains on the electrode sheet, particularly when the removal process is carried out one more time, the electrode powder scattered by the laser light It may interfere with the second removal process by blocking the laser light irradiation. In order to prevent such a problem, the method may further include a step (f) of suctioning and removing the residue after the step (c).

Meanwhile, in the rolling process in the step (d), the thickness of the electrode sheet and the compound coating portion after the coating process of the electrode mixture is reduced to increase the capacitance density, and the adhesion and adhesion between the electrode sheet and the electrode active material contained in the combined coating portion , The electrode sheet is passed between two rolling rollers heated at high temperature to compress the sheet to a desired thickness and density.

In general, it is advantageous in terms of increasing the capacity of a battery to use a double-sided coating electrode rather than a single-sided coating electrode. In one specific example, after performing the above processes (a) to (d) (A) to (d) may be repeatedly performed on 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, the anode current collector may be stainless steel, aluminum, nickel, titanium, sintered carbon, or a surface treated with carbon, nickel, titanium, or silver on the surface of aluminum or stainless steel, A surface treated with carbon, nickel, titanium or silver on the surface of copper, stainless steel, aluminum, nickel, titanium, sintered carbon, copper or stainless steel, or an aluminum-cadmium alloy may be used.

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

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

A coating part for applying an electrode mixture onto the electrode sheet to form a mixture coating part;

A drying unit for removing and solidifying the solvent contained in the compound coating portion;

A coating post-treatment section for removing coating protrusions having a relatively large coating amount at a coating start point of the compound coating section; And

A rolling section for pressing the composite coating portion from which the coating projection is removed;

As shown in FIG.

As described above, the apparatus for manufacturing an electrode for a secondary battery according to the present invention is a device for manufacturing an electrode for a secondary battery, in which an electrode sheet positioned in a sheet conveying unit is moved at a constant speed toward a single direction, a composite coating portion is formed and dried on the electrode sheet, The coating protrusions are removed and pressed to make uniformity. In particular, since the coating after-treatment portion for removing the coating protrusion having a relatively large coating amount is included, the entire thickness of the coated portion can be uniformly formed. As a result, the electrolyte solution impregnation rate becomes uniform in the entire portion of the coated portion, Capacity and life span reduction phenomenon can be prevented.

In one specific example, the post-coating treatment section includes a laser irradiation device. By using the laser irradiation device, damage to the electrode mixture can be minimized, and the coating protrusion can be precisely removed to form an electrode of uniform thickness It is preferable.

In one specific example, the coating unit may further include a suction unit for sucking and removing the residue of the coating protrusion removed from the post-coating treatment unit, wherein the suction unit includes a laser beam scattered by the laser beam, Prevent the investigation from interfering with the second removal process. Thus, more precise removal is possible in the second removal process.

The suction unit may include a vacuum pump or a suction unit so that the electrode powders can be sucked in. However, the scope of the suction unit is not limited thereto.

Meanwhile, the present invention also provides a secondary battery including the electrode manufactured by the above-described method, and the secondary battery is not particularly limited in its kind, but specific examples thereof include a high energy density, a discharge voltage, Lithium secondary batteries, lithium ion secondary batteries, and the like, which have advantages such as high reliability and stability.

In the lithium secondary battery, the secondary battery electrode and the electrode assembly including the electrode fabricated by the manufacturing method of the secondary battery electrode are sealed inside the battery case together with the electrolyte solution.

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

The device may be a mobile phone, a portable computer, a smart phone, a tablet PC, a smart pad, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle (EV), a hybrid electric vehicle (HEV) An electric vehicle including a plug-in hybrid electric vehicle (PHEV); An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; But is not limited to, a system for power storage. The structure of these devices and their fabrication methods are well known in the art, and a detailed description thereof will be omitted herein.

As described above, in the method and apparatus for manufacturing an electrode for a secondary battery according to the present invention, an electrode mixture is coated on an electrode sheet, and then a laser beam of a specific condition is applied to the coating projection portion, As a result, the impregnation rate of the electrolyte solution in the electrode becomes uniform, thereby preventing a decrease in the lithium ion conductivity.

In addition, the electrode manufactured by such a manufacturing method and manufacturing apparatus can provide a secondary battery having a uniform thickness and capacity of the electrode assembly because of the uniform thickness and size of the electrode mixture layer, and having uniform performance have.

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

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

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

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

(a) In the formation of the coating part of the step (110), a slurry type mixture is used to facilitate the coating process. It is not easy to control the amount of the discharged mixture, and thus the thickness of the coating part is unevenly formed. 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. Then, the coating part is solidified through step (b) (120), and the drying step is performed by hot air drying and / or vacuum drying. Next, in step (c) (130), the coating protrusions of the coating portion having a non-uniform thickness are removed to form a uniform coating portion having a uniform overall thickness.

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

The method may further include the step (e) 150 of cutting the non-coated portion after the step (d) and dividing the uncoated portion into units of the coated coating portion.

Referring to FIG. 2, a method 200 for manufacturing an electrode for a secondary battery according to the present invention includes the steps of (c) before the coating protrusion removing process 240, (d) (D) pressing the mixture coating portion in the rolling process 230, and then (c) pressing the coating protrusion portion 210 in the rolling process 230. After the composite coating portion formation and drying process 210 and 220 are performed in the same sequence as the processes 110 and 120 of A uniform coating thickness of uniform thickness is formed through the removal process 240. [ As described above, the electrode manufactured by the manufacturing method according to the present invention can remove the remaining fine coating protrusions even after compression, and thus can have a more uniform thickness.

Meanwhile, (c) after step 240, cutting the uncoated part and dividing the uncoated part into unit parts (e) 250 may be further included.

Referring to FIG. 3, the method 300 for manufacturing an electrode for a secondary battery according to the present invention includes a process in which the removal residue is inhaled. Compared with the manufacturing method 100 of FIG. 1, (c) (D) after the rolling process (350), (c) after the rolling process (350), the coating removal process is performed between the coating protrusion removal process (330) and the rolling process (350) There is a difference in that the protrusion removing process 360 is performed.

That is, the manufacturing method 300 may include (f) the step 340, and (c) the remainder of the coating protrusion removed in the step 330 may prevent the secondary removal process from being hindered. (D) The rolling process 350 is performed. (D) In order to further remove the coating protrusions that may remain fine even after the process 350, (c) the coating protrusion removing process 360 is performed once more do. Thus, by performing the process of removing the coating protrusion twice, it is possible to more completely remove the coating protrusion that has not been removed in the conventional removal process, so that a uniform thickness electrode can be manufactured.

4 is a side cross-sectional view of an assembled coating portion formed on the electrode sheet 402 and the electrode sheet 402 located on the sheet conveying portion 401 as a process of making the thickness of the assembled coating portion on the electrode sheet uniform.

4, an electrode sheet 402 is placed on a sheet conveying part 401 moving at a constant speed toward the direction of the arrow, and a plurality of compound coating parts 420 and 430 are formed on the electrode sheet 402 And the uncoated portions 420 and 430 are spaced apart at uniform intervals so that the uncoated portion of the uniform distance D1 is formed. Specifically, the predetermined distance D1 may be 5 mm to 100 mm. Considering the simplification of the manufacturing process, the distance D1 formed on one electrode sheet may be uniformly formed, Are also included in the scope of the present invention.

When the electrode material mixture coating portion is formed, since the pressure of the mixed material discharge portion is difficult to maintain constant and the fluid mixture is used in the form of a slurry mixture, the thickness of the mixture coating layer can be made uneven. Specifically, since the discharge amount of the front end portion of the mixed coating portion 420 is high, the thickness of the mixed layer is increased to form the coating projection portion 421. The coating protrusion 421 can be removed by irradiating the coating protrusion 421 with the laser beam 411 having a range of 1 to 12 μm by using the laser 410. Accordingly, A uniform mixed coating portion 430 can be manufactured.

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

Referring to FIG. 5, the electrode manufacturing apparatus 500 includes a sheet conveying unit 510 for conveying the electrode sheet in a predetermined direction at the same speed while the electrode sheet is positioned on the upper side, A post-treatment portion 540 for removing coating protrusions having a relatively large coating amount at the coating start portion of the compound coating portion, and a post-coating treatment portion 540 for pressing the coating portion to pressurize the coating portion And a rolled portion 550 for increasing the density.

The post-coating treatment unit 540 may be formed of a laser irradiation apparatus. The coating post-treatment unit 540 may be formed so as to uniformly form the thickness of the compound coating unit by removing the coating projection by irradiating laser light to the mixture coating unit.

As described above, the method and apparatus for manufacturing an electrode for a secondary battery according to the present invention are capable of manufacturing a secondary battery having improved capacity and life of the battery cell because the electrode mixture coating portion is formed to have a uniform thickness at all portions have.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (20)

(a) coating an electrode mixture on one surface of a current collector sheet to form at least one composite coating portion;
(b) drying the mixed coating portion;
(c) removing coating protrusions having a relatively large coating amount at the coating start portion of the composite coating portion, thereby making the overall coating thickness of the coating portion uniform; And
(d) rolling the composite coating portion;
Wherein the first electrode and the second electrode are electrically connected to each other. The method of claim 1, wherein the method is performed in the order of steps (a), (b), (c), and (d). The method of claim 1, wherein the method is performed in the order of steps (a), (b), (d), and (c). The method according to claim 1, wherein the manufacturing method further comprises the step of repeating the step (c) after the steps (a), (b), (c) A method for manufacturing a battery electrode. The method according to claim 1, wherein, in the step (a), an electrode mixture is coated on the moving electrode sheet so that a plurality of mixture coating portions are formed at predetermined intervals, and the electrode sheet is exposed to the outside And a non-ionized portion is disposed on the surface of the electrode. [6] The method of claim 5, further comprising the step (e) of cutting the non-coated portion to divide the uncoated portion into units of the coated coating portion. The method according to claim 5, wherein the length of the non-coated portion, which is the separation distance of the compound coating portions, is in the range of 5 mm to 100 mm. The method of claim 1, wherein the step (b) is performed by hot air and / or vacuum drying. The method according to claim 1, wherein in step (c), the coating protrusion is removed by irradiating laser light. 10. The method of claim 9, wherein an output wavelength of the laser light is in a range of 1 [mu] m to 12 [mu] m. The method as claimed in claim 9, wherein an output capacity of the laser beam is 1 kW to 15 kW. The method of claim 1, wherein the thickness of the coating is in the range of 10 탆 to 100 탆. The method according to claim 1, further comprising the step (f) after the step (c) of sucking and removing the remnants of the coating protrusions cut by the laser. The method for manufacturing an electrode for a secondary battery according to claim 1, wherein the steps (a) to (d) are repeatedly performed on the other surface of the electrode sheet. An apparatus for use in a method for manufacturing an electrode for a secondary battery according to any one of claims 1 to 14,
A sheet conveying unit for moving the electrode sheet at a constant speed;
A coating part for applying an electrode mixture onto the electrode sheet to form a mixture coating part;
A drying unit for removing and solidifying the solvent contained in the compound coating portion;
A coating post-treatment section for removing coating protrusions having a relatively large coating amount at a coating start point of the compound coating section; And
A rolling section for pressing the composite coating portion from which the coating projection is removed;
And an electrode for a secondary battery. 16. The apparatus for manufacturing an electrode for a secondary battery according to claim 15, wherein the post-coating treatment section includes a laser irradiation device. The apparatus for manufacturing a secondary battery electrode according to claim 16, further comprising a suction unit for sucking and removing the residue of the coating protrusion removed from the post-coating treatment unit. A secondary battery comprising an electrode for a secondary battery manufactured by the manufacturing method according to any one of claims 1 to 14. The secondary battery according to claim 18, wherein the secondary battery is a lithium secondary battery. The battery pack according to claim 19, wherein the secondary battery is used as a unit battery.

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