Dry electrode manufacturing system, method for manufacturing dry electrodes, electrodes manufactured thereby, and lithium secondary batteries comprising the same

Abstract

The present invention provides a dry electrode manufacturing system comprising: a current collector supply unit for supplying a current collector in one direction; a first feeding unit for supplying electrode powder; and a first pair of pressure rollers for pressurizing a double layer of electrode powder supplied from the first feeding unit to form a film, and then supplying the film-formed double layer of electrode powder onto one surface of the current collector; wherein the first feeding unit comprises an internal space for receiving electrode powder, an outlet for discharging the electrode powder received in the internal space, and a partition wall formed parallel to the direction in which the electrode powder is discharged from the outlet and dividing the internal space and the outlet.

Description

Technology Field

[0001] The present invention relates to a dry electrode manufacturing system, a method for manufacturing a dry electrode, an electrode manufactured thereby, and a lithium secondary battery comprising the same. Background Technology

[0002] Due to the rapid increase in the use of fossil fuels, there is a growing demand for alternative and clean energy. As part of this trend, the fields of power generation and energy storage utilizing electrochemistry are the most actively researched. Currently, secondary batteries are a representative example of electrochemical devices that utilize such electrochemical energy, and their scope of application is steadily expanding. Among these secondary batteries, lithium-ion batteries are representative not only as an energy source for mobile devices but are also being realized as power sources for electric and hybrid electric vehicles that can replace fossil fuel-using vehicles, such as gasoline and diesel cars—which are major causes of air pollution. Furthermore, their application scope is expanding to include uses such as auxiliary power sources through grid integration. The manufacturing process of these lithium-ion batteries is broadly divided into three stages: electrode manufacturing, electrode assembly manufacturing, and formation. The electrode manufacturing process is further subdivided into electrode composite mixing, electrode coating, drying, rolling, slitting, and winding processes. Among these, the electrode mixture mixing process is a process for mixing components for forming an electrode active layer where actual electrochemical reactions occur at the electrode, and more specifically, it involves mixing an electrode active material, which is an essential element of the electrode, other additives such as a conductive material and a filler, a binder for binding between powders and adhesion to a current collector, and a solvent for imparting viscosity and dispersing powders, to produce a fluid slurry.

[0003] The composition mixed in this manner to form the electrode active layer is also referred to as an electrode mixture in a broad sense. Subsequently, an electrode coating process is performed to apply the electrode mixture onto an electrically conductive current collector, and a drying process is carried out to remove the solvent contained in the electrode mixture. Additionally, the electrode is rolled to produce a predetermined thickness.

[0004] Meanwhile, as the solvent contained in the electrode mixture evaporates during the drying process, defects such as pinholes or cracks may be induced in the pre-formed electrode active layer. Additionally, since the inner and outer surfaces of the active layer are not dried uniformly, powder floating may occur due to differences in solvent evaporation rates; that is, powders from the areas that dry first may rise to form gaps with the areas that dry relatively later, potentially degrading the electrode quality.

[0005] To address the above problems, drying devices capable of controlling the evaporation rate of the solvent while ensuring uniform drying of the inner and outer surfaces of the active layer are being considered. However, these drying devices are very expensive and require significant costs and time to operate, which presents disadvantages in terms of manufacturing processability. Therefore, research on manufacturing solvent-free dry electrodes has recently been actively conducted.

[0006] In addition, during wet electrode manufacturing, migration of the binder polymer occurs due to the drying of the electrode slurry, which degrades the rapid charging performance of the battery. To solve this, a double-layer electrode with controlled binder polymer distribution has been proposed.

[0007] Meanwhile, in dry electrode manufacturing, there are fewer problems caused by the migration of such binder polymers, so the distribution of binder polymers in the thickness direction of the manufactured electrode is relatively uniform. However, if the method proposed for wet electrode manufacturing is used in dry electrode manufacturing, it is expected that rapid charging performance will be further improved, and thus there is a need for this. The problem to be solved

[0008] The present invention is designed to solve the aforementioned problems and aims to provide a dry electrode manufacturing system capable of manufacturing a double-layer electrode with different compositional ratios of a binder polymer, an electrode active material, etc., on a current collector, a dry electrode manufacturing method, an electrode manufactured therefrom, and a lithium secondary battery including the same.

[0009] In addition, the present invention aims to provide a dry electrode manufacturing system capable of manufacturing a double-layer electrode without a separate additional process, a dry electrode manufacturing method, an electrode manufactured therefrom, and a lithium secondary battery including the same.

[0010] In addition, the present invention aims to provide a dry electrode manufacturing system and a dry electrode manufacturing method capable of shortening the total coating time and improving manufacturing efficiency.

[0011] However, the problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems will be clearly understood by those skilled in the art from the description of the invention below. means of solving the problem

[0012] To achieve these objectives, according to one aspect of the present invention, a dry electrode manufacturing system, a dry manufacturing method, an electrode manufactured thereby, and a lithium secondary battery including the same are provided according to the following embodiments.

[0013] According to a first embodiment, a dry electrode manufacturing system is provided, comprising: a current collector supply unit that supplies a current collector in one direction; a first feeding unit that supplies electrode powder; and a first pair of pressure rollers that pressurize a double layer of electrode powder supplied from the first feeding unit to form a film, and then supply the film-formed double layer of electrode powder onto one surface of the current collector; wherein the first feeding unit comprises an internal space in which electrode powder is received, an outlet for which the electrode powder received in the internal space is discharged, and a partition wall formed parallel to the direction in which the electrode powder is discharged from the outlet and dividing the internal space and the outlet.

[0014] According to the second embodiment, in the first embodiment, the first feeding section may include a first internal space divided by the partition wall, a first outlet connected to the first internal space, a second internal space, and a second outlet connected to the second internal space.

[0015] According to the third embodiment, in any one of the first and second embodiments, the first pressure roller pair may include: a second roller that receives electrode powder from a first feeding unit and drives the electrode powder to transport it in one direction; and a first roller that is positioned to form a predetermined gap with the second roller and drives in a direction opposite to the rotational direction of the second roller.

[0016] According to the fourth embodiment, in the third embodiment, the rotational speed of the second roller may be faster than the rotational speed of the first roller.

[0017] According to the fifth embodiment, in any one of the first to fourth embodiments, the first feeding section comprises a first internal space divided by the partition wall and a first discharge port connected to the first internal space, a second internal space and a second discharge port connected to the second internal space, and the first pressure roller pair comprises a second roller that receives electrode powder from the first feeding section and drives the electrode powder to be transported in one direction; and a first roller that is arranged to form a predetermined gap with the second roller and drives in a direction opposite to the rotational direction of the second roller, wherein the first discharge port supplies the first electrode powder onto the first roller and the second discharge port supplies the second electrode powder onto the second roller, and the rotational speed of the second roller may be driven faster than the rotational speed of the first roller so that the first electrode powder is stacked on the second electrode powder.

[0018] According to the sixth embodiment, any one of the first to fifth embodiments may further include a first calendering unit for rolling a double layer of filmed electrode powder supplied from a first pair of pressure rollers.

[0019] According to the seventh embodiment, in any one of the first to sixth embodiments, the apparatus comprises: a second feeding unit for supplying electrode powder; and a second pair of pressure rollers for pressurizing the electrode powder layer supplied from the second feeding unit to form a film, and then supplying a film-formed electrode powder double layer on the other side of the current collector. The second feeding unit may include an internal space for receiving electrode powder, an outlet for discharging the electrode powder received in the internal space, and a partition wall formed parallel to the direction in which the electrode powder is discharged from the outlet and dividing the internal space and the outlet.

[0020] According to the eighth embodiment, in the seventh embodiment, the second feeding section includes a third internal space divided by the partition wall and a third outlet connected to the third internal space, a fourth internal space and a fourth outlet connected to the fourth internal space, and the second pressure roller pair includes a third roller that receives electrode powder from the second feeding section and drives the electrode powder to transport it in one direction; and a fourth roller that is arranged to form a predetermined gap with the third roller and drives in a direction opposite to the rotational direction of the third roller, and the rotational speed of the third roller may be faster than the rotational speed of the fourth roller.

[0021] According to the ninth embodiment, in any one of the seventh to eighth embodiments, a second calendering unit for rolling a filmed electrode powder double layer supplied from a second pair of pressure rollers may be further included.

[0022] According to the 10th embodiment, in any one of the 7th to 9th embodiments, the first pressure roller pair and the second pressure roller pair may be arranged so as to be line-symmetric with respect to the current collector.

[0023] According to the 11th embodiment, in any one of the 7th to 10th embodiments, the second pressure roller pair may be arranged so that after the film-formed electrode powder double layer is supplied onto one side of the current collector by the first pressure roller pair, the film-formed electrode powder double layer is supplied onto the other side of the current collector.

[0024] According to the 12th embodiment, a method for manufacturing a dry electrode using an electrode manufacturing system according to any one of the 1st to 11th embodiments is provided, comprising: a step of discharging a first electrode powder onto a first pair of pressure rollers through a first discharge port and discharging a second electrode powder onto a first pair of pressure rollers through a second discharge port; a step of pressurizing the first electrode powder and the second electrode powder discharged onto the first pair of pressure rollers to form a first film-formed electrode powder double layer; and a step of providing the first film-formed electrode powder double layer on one surface of a current collector.

[0025] According to the 13th embodiment, in the 12th embodiment, the first electrode powder comprises a first electrode active material and a first binder polymer, and the second electrode powder comprises a second electrode active material and a second binder polymer, and the first electrode active material and the second electrode active material may be different.

[0026] According to the 14th embodiment, in any one of the 12th to 13th embodiments, prior to the step of providing the first filmed electrode powder double layer on one surface of the current collector, the method may further include the step of controlling the thickness of the first filmed electrode powder double layer.

[0027] According to the 15th embodiment, in any one of the 12th to 14th embodiments, the method may further include the step of discharging a third electrode powder onto a second pair of pressure rollers through a third discharge port and drawing out a third electrode powder onto a second pair of pressure rollers through a fourth discharge port; the step of pressurizing the third electrode powder and the fourth electrode powder discharged onto the second pair of pressure rollers to form a second film-formed electrode powder double layer; and the step of attaching the second film-formed electrode powder double layer to the other side of a current collector.

[0028] According to the 16th embodiment, in the 15th embodiment, prior to the step of providing the second film-formed electrode powder double layer on the other side of the current collector, the method may further include the step of controlling the thickness of the second film-formed electrode powder double layer.

[0029] According to the 17th embodiment, in any one of the 15th to 16th embodiments, the step of providing the second filmed electrode powder double layer on the other side of the current collector may be performed simultaneously with the step of providing the first filmed electrode powder double layer on one side of the current collector.

[0030] According to the 18th embodiment, in any one of the 15th to 17th embodiments, the step of providing the second filmed electrode powder double layer on the other side of the current collector may be attached to the other side of the current collector after the first filmed electrode powder double layer is provided on one side of the current collector.

[0031] According to the 19th embodiment, an electrode for a lithium secondary battery manufactured by any one of the 12th to 18th embodiments is provided.

[0032] According to the 20th embodiment, a lithium secondary battery comprising an electrode for a lithium secondary battery according to the 19th embodiment is provided. Effects of the invention

[0033] A dry electrode manufacturing system according to one embodiment of the present invention can provide a manufacturing apparatus capable of manufacturing a double-layer electrode with different compositional ratios of a binder polymer, an electrode active material, etc., on a current collector without a separate additional process.

[0034] A dry electrode manufacturing system according to one embodiment of the present invention can reduce the number of hot rolling processes by manufacturing a double-layer electrode without a separate additional process, and thereby provide a manufacturing device capable of manufacturing a dry electrode with improved rapid charging and capacity characteristics.

[0035] In addition to the above, the present invention may have various other effects, which are described in each embodiment, or effects that can be easily inferred by a person skilled in the art, etc., will be omitted. Brief explanation of the drawing

[0036] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the aforementioned description; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1 schematically illustrates a dry electrode manufacturing system according to one embodiment of the present invention. FIG. 2 schematically illustrates a dry electrode manufacturing system according to one embodiment of the present invention. FIG. 3 schematically illustrates a dry electrode manufacturing system according to one embodiment of the present invention. FIG. 4 schematically illustrates a dry electrode manufacturing system according to one embodiment of the present invention. FIG. 5 schematically illustrates a dry electrode manufacturing system according to one embodiment of the present invention. FIG. 6 schematically shows a feeding section according to one embodiment of the present invention. FIG. 7 schematically illustrates a feeding section according to one embodiment of the present invention. Specific details for implementing the invention

[0037] Terms and words used in this specification and claims shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0038] The terms used herein are merely for describing exemplary embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0040] <정의>

[0041] Throughout this specification, when a part is described as 'comprising' a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0042] Throughout this specification, the term "combination" or "connection" includes not only cases where one member and another member are directly combined or directly connected, but also cases where one member is indirectly combined or indirectly connected to another member through a connecting member.

[0043] Throughout this specification, terms such as 'top', 'bottom', 'left', 'right', 'front', 'back', 'inside', and 'outside' are used to describe relative positions or directions between components, rather than absolute positions, or may indicate positions or directions in referenced drawings. In addition to these terms themselves, they include words containing them, their derivatives, and words of similar meaning.

[0045] <건식 전극 제조 시스템>

[0046] The present invention provides a dry electrode manufacturing system.

[0047] FIGS. 1 to 5 schematically illustrate a dry electrode manufacturing system (1) according to one embodiment of the present invention.

[0048] According to one aspect of the present invention, the dry electrode manufacturing system (1) of the present invention comprises: a current collector supply unit (not shown) for supplying a current collector (C) in one direction; a first feeding unit (110) for supplying electrode powder; and a first pressure roller pair (210) for pressurizing the electrode powder double layer supplied from the first feeding unit (110) to form a film, and then supplying the film-formed electrode powder double layer (A1) on one surface of the current collector (C); wherein the first feeding unit (110) is characterized by having an internal space (111) for receiving electrode powder, an outlet (122) for discharging the electrode powder received in the internal space (111), and a partition wall (113) formed parallel to the direction in which the electrode powder is discharged from the outlet (122) and dividing the internal space and the outlet.

[0049] This will be explained in more detail below.

[0050] In one embodiment of the present invention, the current collector supply unit supplies the current collector (C) in one direction. The current collector is also referred to as a current collector sheet. The current collector is not particularly limited as long as it possesses high conductivity without causing chemical changes in the battery, and any material used as a current collector in the secondary battery field can be applied without limitation. Examples of materials for the current collector include copper, aluminum, stainless steel, nickel, titanium, calcined carbon, copper, aluminum, or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc. Additionally, a polymer-metal composite material in which copper is formed on at least one or both sides of a polymer support such as PET can also be used as the current collector. Meanwhile, fine irregularities may be formed on the surface of the current collector to increase the adhesion of the adherend. Furthermore, the current collector can take various forms such as a film, sheet, foil, net, porous body, foam, or nonwoven fabric.

[0052] FIGS. 6 and FIGS. 7 schematically illustrate a feeding section according to an embodiment of the present invention.

[0053] In one embodiment of the present invention, the first feeding unit (110) supplies electrode powder. For example, as shown in FIGS. 6 and 7, the first feeding unit (110) has an internal space (111) in which electrode powder is received, an outlet (112) in which the electrode powder received in the internal space (111) is discharged, and a partition (113) formed parallel to the direction in which the electrode powder is discharged from the outlet and dividing the internal space and the outlet.

[0054] In one embodiment of the present invention, the first feeding part (110) functions as a hopper, the internal space (111) accommodates electrode powder, and an outlet (112) is formed for discharging the accommodated electrode powder.

[0055] In one embodiment of the present invention, the first feeding unit may further include an agitator (not shown) that uniformly disperses the electrode powder to prevent clumping of the electrode powder.

[0056] In one embodiment of the present invention, the first feeding unit may further include a roller (not shown) that discharges electrode powder to the outside through an outlet.

[0057] In one embodiment of the present invention, the first feeding unit may further include a stirrer and a driving device (not shown) for driving the roller.

[0058] In one embodiment of the present invention, the partition (113) can divide the first feeding section (110) in a vertical direction, that is, in a direction penetrating the upper and lower portions of the first feeding section (110).

[0059] In one embodiment of the present invention, the first feeding section (110) may be formed such that the upper side is wide and the lower side is narrow. The first feeding section (110) formed in this manner may be configured so that electrode powder is introduced through the upper side and electrode powder is discharged through the lower side. That is, the discharge port (112) may be formed on the lower side of the first feeding section (110). However, it is not necessarily limited thereto.

[0060] In one embodiment of the present invention, the first feeding section (110) may include a first internal space (111a) divided by the partition wall (113), a first outlet (112a) connected to the first internal space, a second internal space (111b), and a second outlet (112b) connected to the second internal space (111b).

[0061] In one embodiment of the present invention, the first feeding unit (110) may further include a powder injection port connected to an electrode powder supply device (not shown) that supplies electrode powder. The electrode powder supply device may be configured to automatically supply electrode powder containing an electrode active material to the first feeding unit.

[0062] In one embodiment of the present invention, the lower portion of the first feeding portion (110) may have a shape that encloses the first pressure roller pair (210). For example, if the first pressure roller pair (210) has a cylindrical shape, the shape of the lower portion of the first feeding portion (110), particularly the outer surface of the first feeding portion, may have a radius of curvature substantially identical to the radius of curvature of the cylinder. That is, the outer surface of the lower portion of the first feeding portion (110) may be identical to the shape of the first pressure roller pair (210). Thus, when the first pressure roller pair (210) rotates, the first feeding portion (110) can be stably positioned regardless of the shape of the first pressure roller pair (210).

[0063] In one embodiment of the present invention, the outer surface of the lower part of the first feeding part (110) and the first pressure roller pair (210) may be positioned with a predetermined gap, and the gap may be 1 mm or less, 700 μm or less, 600 μm or less, or 500 μm or less, and may be 1 μm or more, 5 μm or more, or 10 μm or more.

[0065] In one embodiment of the present invention, the first internal space (111a) may refer to a spaced far from the current collector supply unit in a dry electrode coating device according to FIG. 1. The second internal space (111b) may refer to a space relatively close to the current collector supply unit in contrast to the first internal space.

[0066] In one embodiment of the present invention, the first pair of rollers (210) are each formed in a cylindrical shape and may be installed so that the cylinders are parallel to each other.

[0067] In one embodiment of the present invention, the first pressure roller pair (210) may include a second roller (212) that receives electrode powder from a first feeding unit (110) and drives the electrode powder to transport it in one direction; and a first roller (211) that is positioned to form a predetermined gap with the second roller (212) and drives in a direction opposite to the rotational direction of the second roller (212). The first roller (211) and the second roller (212) may be driven to rotate in opposite directions relative to each other by a predetermined driving device (not shown). Through this, the electrode powder can pass between the first roller (211) and the second roller (212). Meanwhile, the first pressure roller pair (210) may sheet the electrode powder to form a first film-formed electrode powder double layer (A1).

[0068] In one embodiment of the present invention, the first roller (211) may refer to one that is spaced far from the current collector supply unit according to FIG. 1. The second roller (212) may refer to one that is relatively close to the current collector supply unit in comparison to the first roller.

[0069] In one embodiment of the present invention, the first roller (211) and the second roller (212) may have a gap formed within the range of 5 μm to 1,000 μm, 10 μm to 500 μm, or 20 μm to 300 μm.

[0070] In one embodiment of the present invention, the first roller (211) and the second roller (212) can each be controlled within a temperature range of typically 0°C to 200°C or 50°C to 100°C. The first roller (211) can be controlled by taking into account the melting point or glass transition temperature of the binder polymer in the electrode powder.

[0071] In one embodiment of the present invention, the rotational speed of the first roller (211) and the second roller (212) can be adjusted to 0.1 m / min to 150 m / min, 5 m / min to 130 m / min, 10 m / min to 120 m / min, 20 m / min to 100 m / min, and 50 m / min to 80 m / min.

[0072] In one embodiment of the present invention, the press line pressure by the first roller (211) and the second roller (212) may be 0.2 to 30 kN / cm or 0.5 to 10 kN / cm. When the press line pressure range satisfies the range described above, the electrode powder can be distributed more uniformly without clumping.

[0073] In one embodiment of the present invention, the rotational speed of the second roller (212) may be faster than the rotational speed of the first roller (211). For example, the rotational speed of the second roller (212) may be greater than 100% and less than 500%, or greater than or equal to 110% and less than or equal to 400%, based on 100% of the rotational speed of the first roller (211). In this case, the electrode powder supplied from the first feeding section (110) may be conveyed according to the rotational direction of the second roller.

[0074] In one embodiment of the present invention, the first discharge port (112a) supplies a first electrode powder onto the first roller (211), and the second discharge port (112b) supplies a second electrode powder onto the second roller (212). The rotational speed of the second roller (212) may be driven faster than the rotational speed of the first roller (211) so that the first electrode powder is stacked on the second electrode powder. That is, after the first electrode powder is supplied onto the first roller (211) and the second electrode powder is supplied onto the second roller (212), the first electrode powder and the second electrode powder may move together in a certain direction due to a force such as frictional force between them. At this time, if the rotational speed of the second roller is faster than the rotational speed of the first roller, the first electrode powder may be stacked on the second electrode powder and transported in the rotational direction of the second roller.

[0075] Specifically, the first electrode powder and the second electrode powder discharged from the discharge port (112) move to the leading edge between the first roller (211) and the second roller (212) due to friction and the rotational direction of the first pressure roller pair (210). At this time, the electrode powder is compressed by pressure, and the first electrode powder and the second electrode powder can be stacked. At this time, if the rotational speed of the second roller (212) is faster than the rotational speed of the first roller (211), the shear force received by the stack of electrode powders increases further, and the stack of the first electrode powder and the second electrode powder can move toward the second roller (212) while forming a film.

[0076] In one embodiment of the present invention, the dry electrode manufacturing system (1) of the present invention may include a first rolling roller (213) and a second rolling roller (214) that roll the filmed electrode powder double layer (A1) supplied from the first pressing roller pair (210) after passing through the first pressing roller pair (210) to increase the bonding force between the current collector (C) and the filmed electrode powder double layer (A1) as shown in FIG. 2. At this time, the second roller (212) and the first rolling roller (213) may be referred to as the first calendering section (212, 213), and the first rolling roller (213) and the second rolling roller (214) may be referred to as the second calendering section (213, 214).

[0077] At this time, the thickness of the first filmed electrode powder double layer (A1) can be adjusted by the spacing distance and speed ratio between the respective rollers of the first calendering section (212, 213) and the second calendering section (213, 214). For example, the higher the speed ratio of the first calendering section (212, 213) and the second calendering section (213, 214), the thinner the thickness of the first filmed electrode powder double layer (A1) may be. The first rolling roller (213) and the second rolling roller (214) may rotate in opposite directions to each other, thereby reducing the thickness of the filmed electrode powder and increasing the length of the filmed electrode powder in the longitudinal direction, further increasing the density of the filmed electrode powder, and improving uniformity.

[0078] In one embodiment of the present invention, the rotational speed of the second rolling roller (214) may be faster than the rotational speed of the first rolling roller (213). For example, the rotational speed of the second rolling roller (214) may be greater than 100% and less than 400%, or greater than 110% and less than 300%, based on 100% of the rotational speed of the first rolling roller (213). In this case, the transport direction of the filmed electrode powder double layer (A1) in the area adjacent to the first rolling roller (213) and the second rolling roller (214) may be transported in the rotational direction of the second rolling roller (214).

[0079] In one embodiment of the present invention, the first calendering section (212, 213) and the second calendering section (213, 214) may further include at least one rolling roller (not shown) in addition to the first rolling roller (213) and the second rolling roller (214), and the second rolling roller (214) and the added rolling roller (not shown) may constitute another calendering section. In this case, the rolling roller may be arranged to transport a double layer of film-formed electrode powder on the outer surface of the rolling roller. Additionally, the at least one rolling roller (not shown) may have a faster rotational speed the closer it is to the current collector supply section. Furthermore, the at least one rolling roller may have a rotational direction opposite to that of an adjacent rolling roller.

[0081] In one embodiment of the present invention, when supplying a film-formed electrode powder double layer (A1) from the second roller (212) to the current collector (C) without the first calendering section (212, 213) and / or the second calendering section (213, 214), the second roller (212) can perform the role of a lamination roller. That is, the current collector (C) and the electrode powder double layer (A1) can be bonded together by the second roller (212). At this time, a first lamination roller (215) may be further included at a position opposite to the second roller (212), that is, at a position symmetrical to the second roller (212) with respect to the current collector (C), in order to increase the bonding strength of the laminate of the current collector and the electrode powder.

[0082] In one embodiment of the present invention, the size of the first lamination roller (215) may be substantially the same as the size of the second roller (212). For example, the diameter of the first lamination roller (215) may be in the range of 90% to 110% based on 100% of the diameter of the second roller (212).

[0083] The rotational speed of the first lamination roller (215) may be the same as the rotational speed of the second roller (212).

[0084] At this time, the second roller (212) may be spaced apart from the current collector (C) at a predetermined distance, for example, the distance may be 200 μm or less, 150 μm or less, 120 μm or less, 100 μm or less, 90 μm or less, or 80 μm or less, and may be 5 μm or more, 10 μm or more, or 20 μm or more. When the above numerical range is satisfied, the electrode powder double layer (A1) is not broken, the porosity of the electrode powder double layer (A1) is appropriate, and the detachment of particles from the electrode powder double layer (A1) may not occur.

[0086] In one embodiment of the present invention, when the first calendering section (212, 213) and the second calendering section (213, 214) are present, one of the second calendering sections (213, 214) can perform the role of a lamination roller. That is, the current collector (C) and the electrode powder double layer (A1) can be bonded by the second rolling roller (214). At this time, a first lamination roller (215) may be further included at a position facing the second rolling roller (214), that is, at a position symmetrical with respect to the second rolling roller (214) with respect to the current collector (C), in order to increase the bonding strength of the laminate of the current collector and the electrode powder.

[0087] At this time, the second rolling roller (214) may be spaced apart from the current collector (C) at a predetermined distance, for example, the distance may be 200 μm or less, 150 μm or less, 120 μm or less, 100 μm or less, 90 μm or less, or 80 μm or less, and may be 5 μm or more, 10 μm or more, or 20 μm or more.

[0088] In one embodiment of the present invention, the size of the first lamination roller (215) may be substantially the same as the size of the second rolling roller (214). For example, the diameter of the first lamination roller (215) may be in the range of 90% to 110% based on 100% of the diameter of the second rolling roller (214).

[0089] The rotational speed of the first lamination roller (215) may be the same as the rotational speed of the second rolling roller (214).

[0091] In one embodiment of the present invention, the dry electrode manufacturing system (1) of the present invention further comprises: a second feeding unit (120) for supplying electrode powder; and a second pair of pressure rollers (220) for pressurizing the electrode powder layer supplied from the second feeding unit (120) to form a film, and then supplying a double layer of the film-formed electrode powder onto the other side of the current collector. The second feeding unit (120) may have an internal space (121) for receiving electrode powder, an outlet (122) for discharging the electrode powder received in the internal space, and a partition wall (123) formed parallel to the direction in which the electrode powder is discharged from the outlet (122) and dividing the internal space and the outlet.

[0092] In one embodiment of the present invention, the second feeding unit (120) corresponds to the first feeding unit (110), and the first feeding unit (110) and the second feeding unit (120) may be arranged in a line-symmetric relationship with respect to the current collector supply path supplied by the current collector supply unit.

[0093] For example, in one embodiment of the present invention, the second feeding section (120) includes a third internal space (121a) divided by the partition wall (123), a third outlet (122a) connected to the third internal space (121a), a fourth internal space (121b), and a fourth outlet (122b) connected to the fourth internal space (121b); the second pressure roller pair (220) includes a third roller (221) that receives electrode powder from the second feeding section (120) and drives the electrode powder to transport it in one direction; and a fourth roller (222) that is positioned to form a predetermined gap with the third roller (221) and drives in a direction opposite to the rotational direction of the third roller (221), and the rotational speed of the third roller (221) may be faster than the rotational speed of the fourth roller (222). At this time, the third internal space (121a) corresponds to the second internal space (111b), the fourth internal space (121b) corresponds to the first internal space (111a), the third discharge port (122a) corresponds to the second discharge port (112b), and the fourth discharge port (122b) may correspond to the first discharge port (112a). Additionally, the third roller (221) may correspond to the second roller (212), and the fourth roller (222) may correspond to the first roller (211).

[0094] In one embodiment of the present invention, the details regarding the third internal space (121a), the fourth internal space (121b), the third discharge port (122a), the fourth discharge port (122b), the third roller (221), and the fourth roller (222) are substituted with the foregoing description.

[0095] In one embodiment of the present invention, the rotational speed of the first roller (211) may be the same as the rotational speed of the fourth roller (222), and the rotational speed of the second roller (212) may be the same as the rotational speed of the third roller (221). By doing so, the uniformity of the electrode active material layer on both sides of the current collector may be even better.

[0096] In one embodiment of the present invention, the dry electrode manufacturing system (1) of the present invention may include a third rolling roller (223) and a fourth rolling roller (224) that roll the filmed electrode powder double layer (A2) supplied from the second pressing roller pair (220) after passing through the second pressing roller pair (220) in order to increase the bonding force between the current collector (C) and the filmed electrode powder double layer (A2), as shown in FIG. 4. At this time, the third roller (221) and the third roller (223) may be referred to as the third calendering section (221, 223), and the third rolling roller (223) and the fourth rolling roller (224) may be referred to as the fourth calendering section (223, 224).

[0097] At this time, the thickness of the second filmed electrode powder double layer (A2) can be adjusted by the spacing distance and speed ratio between the respective rollers of the third calendering section (221, 223) and the fourth calendering section (223, 224). For example, the higher the speed ratio of the third calendering section (221, 223) and the fourth calendering section (223, 224), the thinner the thickness of the second filmed electrode powder double layer (A2) may be. The third rolling roller (223) and the fourth rolling roller (224) may rotate their respective rollers in opposite directions to reduce the thickness of the filmed electrode powder and increase the length of the filmed electrode powder in the longitudinal direction, thereby further increasing the density of the filmed electrode powder and improving its uniformity.

[0099] In one embodiment of the present invention, as illustrated in FIG. 3, when the dry electrode manufacturing system (1) of the present invention supplies a film-formed electrode powder double layer (A1, A2) from the second roller (212) and the third roller (221) to the current collector (C) without the first calendering section (212, 213), the second calendering section (213, 214), the third calendering section (221, 223), and / or the fourth calendering section (223, 224), the second roller (212) and the third roller (221) can perform the roles of a lamination roller and a backup roller. By doing so, the film-formed electrode powder double layer (A1, A2) can be better bonded to the current collector (C). Meanwhile, at this time, the second roller (212) and the third roller (221) may be positioned in a position that is line-symmetric with respect to the current collector (C).

[0100] At this time, the second roller (212) and the third roller (221) may each be spaced apart from the current collector (C) at a predetermined distance, for example, the distance may be 200 μm or less, 150 μm or less, 120 μm or less, 100 μm or less, 90 μm or less, or 80 μm or less, and may be 5 μm or more, 10 μm or more, or 20 μm or more. For example, the second roller (212) and the third roller (221) may be 400 μm or less, 300 μm or less, or 250 μm or less, and may be 10 μm or more, or 20 μm or more.

[0101] In one embodiment of the present invention, the third calendering section (221, 223) and the fourth calendering section (223, 224) may further include at least one rolling roller (not shown) in addition to the third rolling roller (223) and the fourth rolling roller (224), and the fourth rolling roller (224) and the added rolling roller (not shown) may constitute another calendering section. In this case, the rolling roller may be arranged to transport a film-formed electrode powder double layer on the outer surface of the rolling roller. Additionally, the at least one rolling roller (not shown) may have a faster rotational speed the closer it is to the current collector supply section. Furthermore, the at least one rolling roller may have a rotational direction opposite to that of an adjacent rolling roller.

[0103] In one embodiment of the present invention, as illustrated in FIG. 4, the dry electrode manufacturing system (1) of the present invention may include a first calendering section (212, 213), a second calendering section (213, 214), a third calendering section (221, 223), and a fourth calendering section (223, 224), and the second rolling roller (214) and the fourth rolling roller (224) may perform the role of a lamination roller. By doing so, the filmed electrode powder double layer (A1, A2) can be better bonded to the current collector (C). Meanwhile, the second rolling roller (214) and the fourth rolling roller (224) may be positioned in a line-symmetrical arrangement with respect to the current collector (C).

[0104] At this time, the second rolling roller (214) and the fourth rolling roller (224) may each be spaced apart from the current collector (C) at a predetermined distance, for example, the distance may be 200 μm or less, 150 μm or less, 120 μm or less, 100 μm or less, 90 μm or less, or 80 μm or less, and may be 5 μm or more, 10 μm or more, or 20 μm or more.

[0106] In one embodiment of the present invention, the first pressure roller pair (210) and the second pressure roller pair (220) may be arranged so as to be symmetric with respect to the current collector.

[0108] In one embodiment of the present invention, as illustrated in FIG. 5, the dry electrode manufacturing system (1) of the present invention may include a first calendering unit (212, 213), a second calendering unit (213, 214), a third calendering unit (221, 223), and a fourth calendering unit (223, 224), and the second rolling roller (214) of the second calendering unit (213, 214) and the fourth rolling roller (224) of the fourth calendering unit (223, 224) may not be located in positions facing each other.

[0109] For example, the second pressure roller pair (220) may be arranged so that after the film-formed electrode powder double layer (A1) formed by the first pressure roller pair (210) is supplied onto one side of the current collector (C), the film-formed electrode powder double layer (A2) is supplied onto the other side of the current collector (C). Meanwhile, in one embodiment of the present invention, as shown in FIG. 5, the first calendering section (212, 213), the second calendering section (213, 214), the third calendering section (221, 223), and the fourth calendering section (223, 224) may all be present, or at least one of the first calendering section (212, 213), the second calendering section (213, 214), the third calendering section (221, 223), and the fourth calendering section (223, 224) may be present.

[0110] At this time, a first lamination roller (215) may be further included to increase the bonding force between the current collector (C) and the film-formed electrode powder double layer (A1) at a position facing the second rolling roller (214) of the second calendering section (213, 214), that is, a position symmetrical with respect to the current collector (C) with respect to the rolling roller (214) of the second calendering section (213, 214); and at this time, a second lamination roller (225) may be further included to increase the bonding force between the current collector (C) and the electrode powder laminate (C2) at a position facing the fourth rolling roller (224) of the fourth calendering section (223, 224), that is, a position symmetrical with respect to the current collector (C) with respect to the rolling roller (224) of the second calendering section.

[0112] In one embodiment of the present invention, the size of the first lamination roller (215) may be substantially the same as the size of the second rolling roller (214). For example, the diameter of the first lamination roller (215) may be in the range of 90% to 110% based on 100% of the diameter of the second rolling roller (214).

[0113] The rotational speed of the first lamination roller (215) may be the same as the rotational speed of the second rolling roller (214).

[0114] In one embodiment of the present invention, the size of the second lamination roller (225) may be substantially the same as the size of the fourth rolling roller (214). For example, the diameter of the second lamination roller (225) may be in the range of 90% to 110% based on 100% of the diameter of the fourth rolling roller (214).

[0115] The rotational speed of the second lamination roller (225) may be the same as the rotational speed of the fourth rolling roller (214).

[0117] <건식 전극 제조 방법>

[0118] The present invention provides a method for manufacturing a dry electrode.

[0119] According to one aspect of the present invention, a dry electrode manufacturing method of the present invention is a method for manufacturing a dry electrode using the aforementioned electrode manufacturing system, comprising: a step of discharging a first electrode powder onto a first pair of pressure rollers through a first discharge port and discharging a second electrode powder onto a first pair of pressure rollers through a second discharge port; a step of pressurizing the first electrode powder and the second electrode powder discharged onto the first pair of pressure rollers to form a first film-formed electrode powder double layer; and a step of providing the first film-formed electrode powder double layer onto one surface of a current collector.

[0120] In one embodiment of the present invention, the first electrode powder comprises a first electrode active material and a first binder polymer, and the second electrode powder comprises a second electrode active material and a second binder polymer, and the first electrode active material and the second electrode active material may be different.

[0121] The first electrode active material and the second electrode active material may be positive electrode active material or negative electrode active material.

[0122] In one embodiment of the present invention, when the first electrode active material and the second low electrode active material are positive electrode active materials, the positive electrode active material is not limited to lithium transition metal oxide or lithium metal iron phosphate, provided it is in the form of a metal oxide, and, for example, may be a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7, etc.; chemical formula LiNi 1-x Mx Ni-site type lithium nickel oxide represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 ~ 0.3); chemical formula LiMn 2-x M x Lithium manganese composite oxides represented by O2 (where M = Co, Ni, Fe, Cr, Zn, or Ta, and x = 0.01 to 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu, or Zn); Li in which part of the Li of the chemical formula is substituted with aluminum ions. 1+x (Ni a Co b Mn c Al d ) 1-x Examples include O2 (x = 0 ~ 0.03, a = 0.3 ~ 0.95, b = 0.01 ~ 0.35, c = 0.01 ~ 0.5, d = 0.001 ~ 0.03, a+b+c+d=1); lithium metal phosphate LiMPO4 (where M is M = Fe, CO, Ni, or Mn), disulfide compounds; Fe2(MoO4)3, etc., but are not limited to these.

[0123] In one embodiment of the present invention, when the first electrode active material and the second low electrode active material are negative electrode active materials, the negative electrode active material is a graphite-based carbon material such as, for example, non-graphitizable carbon, natural graphite, or artificial graphite; Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1, 2, and 3 elements of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소; 규소계 합금; 주석; 주석계 합금; SiO x(0 <X≤2), SiO, SiO / C, SiO2등의 규소계 재료; SnO, SnO2, 등의 주석계 재료; PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, 및 Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료 등을 사용할 수 있으나, 이들만으로 한정되는 것은 아니다.

[0124] In one embodiment of the present invention, the first electrode active material and the second electrode active material may each include two or more different electrode active material materials. Specifically, the electrode powder may include two or more different electrode active material materials within a single particle. For example, the dry electrode powder may include artificial graphite and natural graphite as electrode active materials, and the artificial graphite and natural graphite may be mixed in a predetermined ratio.

[0126] In one embodiment of the present invention, there is no limitation on the type of the first binder polymer and the second binder polymer when used as binder polymers for a lithium secondary battery. The first binder polymer and the second binder polymer may each include, for example, a diene-based polymer, an acrylate-based polymer, an olefin-based polymer, a fluorine-based polymer, a styrene-based polymer, or two or more of these.

[0127] In one embodiment of the present invention, examples of the diene-based polymer may include a polymer comprising monomer units derived from conjugated dienes such as butadiene and isoprene, and hydrogenated products thereof. The proportion of monomer units derived from conjugated dienes in the diene-based polymer may be at least 40 wt%, preferably at least 50 wt%, and more preferably at least 60 wt%.

[0128] Specifically, examples include conjugated diene homopolymers such as polybutadiene or polyisoprene; aromatic vinyl-conjugated diene copolymers such as styrene-butadiene copolymer (SBR) which may be carboxylated; cyanated vinyl-conjugated diene copolymers such as acrylonitrile-butadiene copolymer (NBR); hydrogenated SBR, hydrogenated NBR, etc.

[0129] In one embodiment of the present invention, the styrene-based polymer is a polymer having repeating units derived from styrene monomers, and may include a styrene homopolymer (polystyrene), a styrene copolymer, etc. Examples of the styrene copolymer may include a styrene-ethylene-butadiene copolymer, a styrene-butadiene-propylene copolymer, a styrene-isoprene copolymer, a styrene-n-butyl-itaconic acid-methyl-acrylonitrile methacrylate copolymer, a styrene-butadiene block copolymer, a styrene-butadiene-styrene block copolymer, a styrene-ethylene-butylene-styrene block copolymer, a styrene-isoprene block copolymer, a styrene-ethylene-propylene-styrene block copolymer, and other block copolymers.

[0130] Examples of the above acrylate-based polymers include polymers containing monomer units derived from acrylic acid esters and / or methacrylic acid esters. The proportion of monomer units derived from acrylic acid esters and / or methacrylic acid esters in the acrylate-based polymer may be at least 40 wt%, preferably at least 50 wt%, and more preferably at least 60 wt%. Specific examples of acrylate-based polymers include cross-linked acrylate-based polymers such as 2-ethylhexyl-methacrylic acid-acrylonitrile-ethylene glycol dimethacrylate copolymer, 2-ethylhexyl-methacrylic acid-methacrylonitrile-diethylene glycol dimethacrylate copolymer, 2-ethylhexyl-styrene-methacrylic acid-ethylene glycol dimethacrylate copolymer, butyl acrylate-acrylonitrile-diethylene glycol dimethacrylate copolymer, and butyl acrylate-acrylic acid-trimethylolpropane trimethacrylate copolymer; Examples include copolymers of ethylene and (meth)acrylic acid esters, such as ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-ethyl methacrylate copolymer; and graft polymers obtained by grafting a radical polymerizable monomer onto the copolymers of ethylene and (meth)acrylic acid esters. Meanwhile, examples of radical polymerizable monomers used in the graft polymers include methyl methacrylate, acrylonitrile, and methacrylic acid. Additionally, copolymers of ethylene and (meth)acrylic acid, such as ethylene-acrylic acid copolymers and ethylene-methacrylate copolymers, can be used as dispersion-type binders.

[0131] In one embodiment of the present invention, the olefin-based polymer may include at least one of polyethylene, polypropylene, and polybutylene. In one embodiment of the present invention, the electrode powder comprising a fiberizing binder may include the polyethylene polymer.

[0132] The above-mentioned fluorine-based polymer may include polyvinylidene fluoride copolymers such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), and PVDF-HFP, and more specifically, may include polytetrafluoroethylene (PTFE), and even more specifically, may be polytetrafluoroethylene (PTFE). In one embodiment of the present invention, the electrode powder comprising a fiberizing binder may include polytetrafluoroethylene.

[0133] Meanwhile, in one embodiment of the present invention, the first binder polymer and the second binder polymer may comprise two or more different materials. For example, the electrode powder may be a mixture of styrene-butadiene rubber (SBR) and an acrylate-based polymer in a predetermined ratio as binder polymers.

[0135] In one embodiment of the present invention, the first electrode powder may further include a first conductive material. Additionally, the second electrode powder may further include a second conductive material.

[0136] The first and second conductive materials are not particularly limited as long as they possess conductivity without causing chemical changes in the battery, and for example, graphite such as natural graphite or artificial graphite; carbon black-based carbon compounds such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; conductive fibers such as carbon fibers or metal fibers; metal powders such as carbon fluoride, aluminum, or nickel powder; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive materials such as polyphenylene derivatives may be used. In a specific embodiment, to ensure uniform mixing of the conductive materials and to improve conductivity, the conductive materials may include activated carbon, graphite, carbon black, carbon nanotubes, or a mixture of two or more of these. More specifically, the conductive materials may include activated carbon.

[0137] According to one embodiment of the present invention, the conductive material has a specific surface area of ​​30 m² 2 / g to 1,400 m 2 / g and may have a spherical shape. In this case, the size of the primary particles of the conductive material having a spherical shape may be, for example, 10 nm to 100 nm, specifically 15 nm to 70 nm, but is not limited thereto.

[0138] According to another embodiment of the present invention, the conductive material has a specific surface area of ​​10 m² 2 / g to 400 m 2 It may have a tubular shape of / g. In this case, the conductive material having a tubular shape may have a cross-sectional diameter in a direction orthogonal to the longitudinal direction of 0.1 to 3 nm, specifically 0.3 to 1.5 nm, but is not limited thereto.

[0139] In one embodiment of the present invention, the first electrode powder or the second electrode powder may contain two or more different conductive materials within a single powder. For example, the first electrode powder may have carbon black and carbon nanotubes mixed in a predetermined ratio as the first conductive material.

[0140] In one embodiment of the present invention, the mixing ratio of the electrode active material, conductive material, and binder polymer in the first electrode powder or the second electrode powder may be such that the electrode active material: conductive material: electrode binder polymer are each included in a weight ratio of 80 to 99 parts by weight: 0.5 to 10 parts by weight: 0.5 to 10 parts by weight, and more specifically, may be included in a weight ratio of 90 to 99 parts by weight: 0.5 to 5 parts by weight: 0.5 to 10 parts by weight.

[0142] In one embodiment of the present invention, the electrode powder may refer to an electrode material, such as an electrode active material, that is entangled by a fibrous binder polymer. The electrode powder may be manufactured by fibrousizing the binder polymer through a kneading process of a dry blend in which a conductive material and a binder polymer are mixed. The kneading may be performed, for example, using a dough mixer such as a kneader, and as the binder polymer is fibrous through this kneading, the electrode active material and the conductive material may be combined or connected to obtain a lump-shaped mixture. Subsequently, the obtained lump-shaped blend may be crushed to obtain the electrode powder.

[0143] In one embodiment of the present invention, the electrode powder may be in the form of granules produced by a spray drying method. The granules may be produced by a step of preparing a slurry by mixing an electrode active material, a binder polymer, etc., with a dispersion medium, and then spray-drying the slurry. The electrode powder in the form of granules produced in this way may be in the form of secondary particles in which two or more electrode active materials are bound and assembled by a binder polymer.

[0144] In one embodiment of the present invention, the spray drying method may be a method of drying the slurry in hot air. Specifically, the spray method may be performed by a rotating disc method or a nozzle pressurization method. The rotating disc method is a method in which the slurry is introduced near the center of a high-speed rotating disc, and the slurry is placed outside the disc by the centrifugal force of the disc, and then dried in a mist form. The rotation speed of the disc depends on the size of the disc, but is usually 5,000 rpm to 35,000 rpm, preferably 15,000 rpm to 30,000 rpm. Meanwhile, the nozzle pressurization method is a method in which the slurry is passed through a thin nozzle while simultaneously spraying a high-pressure fluid, such as air or another liquid, to spray it in a mist form for drying.

[0145] In one embodiment of the present invention, the electrode powder may include an electrode powder in which an electrode active material, etc. is entangled by a fibrous binder polymer, an electrode powder in the form of a granule, or both.

[0147] In one embodiment of the present invention, the dry electrode manufacturing method may further comprise: a step of discharging a third electrode powder onto a second pair of pressure rollers through a third discharge port and discharging a third electrode powder onto a second pair of pressure rollers through a fourth discharge port; a step of pressurizing the third electrode powder and the fourth electrode powder discharged onto the second pair of pressure rollers to form a second film-formed electrode powder double layer; and a step of attaching the second film-formed electrode powder double layer to the other side of a current collector.

[0148] At this time, the third discharge port corresponds to the second discharge port, and the fourth discharge port may correspond to the first discharge port. Additionally, the third roller may correspond to the second roller, and the fourth roller may correspond to the first roller.

[0149] In one embodiment of the present invention, the details regarding the third internal space, the fourth internal space, the third discharge port, the fourth discharge port, the third roller, and the fourth roller are substituted for those described above.

[0151] In one embodiment of the present invention, the first electrode powder and the second electrode powder are pressurized to form a first film-formed electrode powder double layer. At this time, the first powder may form a first electrode active material layer, and the second powder may form a second electrode active material layer. The first electrode active material layer may be formed on one surface of a current collector, and the second electrode active material layer may be formed on the first electrode active material layer.

[0152] In one embodiment of the present invention, the third electrode powder and the fourth electrode powder are pressurized to form a second film-formed electrode powder double layer. At this time, the fourth powder may form a fourth electrode active material layer, and the third powder may form a third electrode active material layer. The fourth electrode active material layer may be formed on the other side of the current collector, and the third electrode active material layer may be formed on the fourth electrode active material layer.

[0153] In one embodiment of the present invention, when the second electrode active material and the third electrode active material are negative electrodes, a silicon-based negative electrode active material, for example, SiO₂ x (0 <x≤2), SiO, SiO / C, SiO2등을 더 포함할 수 있다.

[0154] In one embodiment of the present invention, the silicon-based negative electrode active material may be included in an amount of 2% to 15% by weight or 3% to 10% by weight based on 100% by weight of the first electrode active material and the second electrode active material. In this case, the capacity characteristics of the battery may be excellent.

[0155] In one embodiment of the present invention, the dry electrode manufacturing method of the present invention may further include a step of controlling the thickness of the first filmed electrode powder double layer prior to the step of providing the first filmed electrode powder double layer on one surface of the current collector.

[0156] In one embodiment of the present invention, the dry electrode manufacturing method of the present invention may further include a step of controlling the thickness of the second film-formed electrode powder double layer prior to the step of providing the second film-formed electrode powder double layer on the other side of the current collector.

[0157] In one embodiment of the present invention, the step of providing the second film-formed electrode powder double layer on the other side of the current collector may be performed simultaneously with the step of providing the first film-formed electrode powder double layer on one side of the current collector.

[0158] In one embodiment of the present invention, the step of providing the second film-formed electrode powder double layer on the other side of the current collector may be to attach the first film-formed electrode powder double layer to the other side of the current collector after it has been provided on one side of the current collector.

[0159] Meanwhile, in one embodiment of the present invention, the dry electrode manufacturing method of the present invention includes a step of adjusting the thickness of the second film-formed electrode powder double layer prior to the step of providing the second film-formed electrode powder double layer on the other side of the current collector, wherein the step of providing the second film-formed electrode powder double layer on the other side of the current collector may be attached to the other side of the current collector after the first film-formed electrode powder double layer is provided on one side of the current collector. In this case, the thickness of the second film-formed electrode powder double layer can be adjusted more precisely by considering the thickness of the first film-formed electrode powder double layer, and thereby the uniformity of the dry electrode manufactured may be even better.

[0161] <리튬 이차전지>

[0162] The present invention provides an electrode for a lithium secondary battery manufactured by the above-described dry electrode manufacturing method and a lithium secondary battery including the same.

[0163] In one embodiment of the present invention, a lithium secondary battery is provided in which an electrode assembly comprising a positive electrode, a negative electrode, and an insulating film is embedded in a battery case (cylindrical case, prismatic case, pouch, etc.). In this case, at least one of the positive electrode and the negative electrode may be the aforementioned electrode. For example, the negative electrode may be a dry electrode. Meanwhile, the battery may further include a lithium-containing non-aqueous electrolyte.

[0165] When a separator is included in the electrode assembly, the separator may be a porous polymer film made of a polyolefin-based polymer, such as a conventional porous polymer film used as a separator, for example, an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, used alone or in a laminated form. Additionally, an insulating thin film having high ion permeability and mechanical strength may be used. The separator may include a safety reinforced separator (SRS) in which a ceramic material is thinly coated on the surface of the separator. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used, but is not limited thereto.

[0166] Alternatively, if the insulating film is a solid electrolyte film, the solid electrolyte film may include a solid electrolyte material, and the solid electrolyte material may include one or more of an oxide-based solid electrolyte, a sulfide-based solid electrolyte, and a polymer-based solid electrolyte. Furthermore, if the lithium-ion secondary battery is an all-solid-state battery, the dry electrode of the present invention may further include the aforementioned solid electrolyte material.

[0167] The above electrolyte comprises a lithium salt as an electrolyte and an organic solvent for dissolving it.

[0168] The above lithium salt may be used without limitation as long as it is one commonly used in electrolytes for secondary batteries, for example, as the anion of the above lithium salt, F - , Cl - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , PF6 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - One type selected from the group consisting of can be used.

[0169] The organic solvent included in the above electrolyte may be any commonly used solvent without limitation, and one or more selected from the group consisting of propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, dipropyl carbonate, dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, vinylene carbonate, sulfolane, gamma-butyrolactone, propylene sulfite, and tetrahydrofuran may be used.

[0170] In particular, among the above carbonate-based organic solvents, ethylene carbonate and propylene carbonate, which are cyclic carbonates, are high-viscosity organic solvents with high dielectric constants that effectively dissociate lithium salts in the electrolyte, so they can be used preferably. Furthermore, if low-viscosity, low-dielectric constant linear carbonates such as dimethyl carbonate and diethyl carbonate are mixed with these cyclic carbonates in appropriate proportions, an electrolyte with high electrical conductivity can be produced, making it even more preferable to use.

[0171] Optionally, the electrolyte stored according to the present invention may further include additives such as an overcharge prevention agent included in conventional electrolytes.

[0172] A lithium secondary battery according to one embodiment of the present invention may be completed by forming an electrode assembly by placing a separator between a positive electrode and a negative electrode, placing the electrode assembly in, for example, a pouch, a cylindrical battery case, or a prismatic battery case, and then injecting an electrolyte. Alternatively, a lithium secondary battery may be completed by stacking the electrode assemblies, impregnating them with an electrolyte, placing the resulting product into a battery case, and sealing it.

[0174] Meanwhile, since the specific structure of the lithium secondary battery in the present invention is as previously known, a description thereof is omitted in this specification.

[0176] In the present invention, the aforementioned embodiments may each be implemented independently. Alternatively, it is obvious that two or more of the aforementioned embodiments may be implemented in combination. Explanation of the symbols

[0178] 1: Dry electrode manufacturing system, 110: First feeding section, 111: Internal space, 111a: First internal space, 111b: Second internal space, 112: Discharge port, 112a: First discharge port, 112b: Second discharge port, 113: Partition wall, 120: Second feeding section, 121: Internal space, 121a: Third internal space, 121b: Fourth internal space, 122: Discharge port, 122a: Third discharge port, 122b: Fourth discharge port, 123: Partition wall, 210: First pressure roller pair, 211: First roller, 212: Second roller, 213: First rolling roller, 214: Second rolling roller, 215: First backup roller, 220: Second pressure roller pair, 221: 3rd roller, 222: 4th roller, 223: 3rd rolling roller, 224: 4th rolling roller, 225: 2nd backup roller, C: Current collector, A1: 1st filmed electrode powder double layer, A2: 2nd filmed electrode powder double layer

Claims

Claim 1 A dry electrode manufacturing system comprising: a current collector supply unit that supplies a current collector in one direction; a first feeding unit that supplies electrode powder; and a first pair of pressure rollers that pressurize a double layer of electrode powder supplied from the first feeding unit to form a film, and then supply the film-formed double layer of electrode powder onto one surface of the current collector; wherein the first feeding unit comprises an internal space in which electrode powder is received, an outlet for which the electrode powder received in the internal space is discharged, and a partition wall formed parallel to the direction in which the electrode powder is discharged from the outlet and dividing the internal space and the outlet. Claim 2 A dry electrode manufacturing system according to claim 1, wherein the first feeding section comprises a first internal space divided by the partition wall, a first outlet connected to the first internal space, a second internal space, and a second outlet connected to the second internal space. Claim 3 A dry electrode manufacturing system according to claim 1, wherein the first pressure roller pair comprises: a second roller that receives electrode powder from a first feeding section and drives the electrode powder to transport it in one direction; and a first roller that is positioned to form a predetermined gap with the second roller and drives in a direction opposite to the rotational direction of the second roller. Claim 4 A dry electrode manufacturing system according to claim 3, characterized in that the rotational speed of the second roller is faster than the rotational speed of the first roller. Claim 5 A dry electrode manufacturing system according to claim 1, wherein the first feeding section comprises a first internal space divided by the partition wall and a first discharge port connected to the first internal space, a second internal space and a second discharge port connected to the second internal space, and the first pressure roller pair comprises a second roller that receives electrode powder from the first feeding section and drives the electrode powder to transport it in one direction; and a first roller that is arranged to form a predetermined gap with the second roller and drives in a direction opposite to the rotational direction of the second roller, wherein the first discharge port supplies a first electrode powder onto the first roller and the second discharge port supplies a second electrode powder onto the second roller, and the rotational speed of the second roller is driven faster than the rotational speed of the first roller so that the first electrode powder is stacked on the second electrode powder. Claim 6 A dry electrode manufacturing system according to claim 1, further comprising a first calendering unit for rolling a double layer of filmed electrode powder supplied from a first pair of pressure rollers. Claim 7 A dry electrode manufacturing system according to claim 1, comprising: a second feeding unit for supplying electrode powder; and a second pair of pressure rollers for pressurizing the electrode powder layer supplied from the second feeding unit to form a film, and then supplying a film-formed electrode powder double layer onto the other side of the current collector; wherein the second feeding unit comprises an internal space for receiving electrode powder, an outlet for discharging the electrode powder received in the internal space, and a partition wall formed parallel to the direction in which the electrode powder is discharged from the outlet and dividing the internal space and the outlet. Claim 8 A dry electrode manufacturing system according to claim 7, wherein the second feeding section comprises a third internal space divided by the partition wall and a third discharge port connected to the third internal space, a fourth internal space and a fourth discharge port connected to the fourth internal space, and the second pressure roller pair comprises a third roller that receives electrode powder from the second feeding section and drives the electrode powder to transport it in one direction; and a fourth roller that is arranged to form a predetermined gap with the third roller and drives in a direction opposite to the rotational direction of the third roller, wherein the rotational speed of the third roller is faster than the rotational speed of the fourth roller. Claim 9 A dry electrode manufacturing system according to claim 7, further comprising a second calendering unit for rolling a double layer of filmed electrode powder supplied from a second pair of pressure rollers. Claim 10 A dry electrode manufacturing system according to claim 7, characterized in that the first pair of pressure rollers and the second pair of pressure rollers are arranged to be line-symmetric with respect to the current collector. Claim 11 A dry electrode manufacturing system according to claim 7, characterized in that the second pair of pressure rollers is arranged such that, after the film-formed electrode powder double layer is supplied onto one side of the current collector by the first pair of pressure rollers, the film-formed electrode powder double layer is supplied onto the other side of the current collector. Claim 12 A method for manufacturing a dry electrode using an electrode manufacturing system according to claim 1, comprising: a step of discharging a first electrode powder onto a first pair of pressure rollers through a first discharge port and discharging a second electrode powder onto a first pair of pressure rollers through a second discharge port; a step of pressurizing the first electrode powder and the second electrode powder discharged onto the first pair of pressure rollers to form a first film-formed electrode powder double layer; and a step of providing the first film-formed electrode powder double layer onto one surface of a current collector; characterized by comprising: a dry electrode manufacturing method. Claim 13 A dry electrode manufacturing method according to claim 12, wherein the first electrode powder comprises a first electrode active material and a first binder polymer, and the second electrode powder comprises a second electrode active material and a second binder polymer, and wherein the first electrode active material and the second electrode active material are different. Claim 14 A dry electrode manufacturing method according to claim 12, further comprising the step of controlling the thickness of the first filmed electrode powder double layer prior to the step of providing the first filmed electrode powder double layer on one surface of the current collector. Claim 15 A dry electrode manufacturing method according to claim 12, further comprising: a step of discharging a third electrode powder onto a second pair of pressure rollers through a third discharge port and drawing out a third electrode powder onto a second pair of pressure rollers through a fourth discharge port; a step of pressurizing the third electrode powder and the fourth electrode powder discharged onto the second pair of pressure rollers to form a second film-formed electrode powder double layer; and a step of attaching the second film-formed electrode powder double layer to the other side of a current collector. Claim 16 A dry electrode manufacturing method according to claim 15, further comprising the step of controlling the thickness of the second film-formed electrode powder double layer prior to the step of providing the second film-formed electrode powder double layer on the other side of the current collector. Claim 17 A dry electrode manufacturing method according to claim 15, characterized in that the step of providing the second film-formed electrode powder double layer on the other side of the current collector is performed simultaneously with the step of providing the first film-formed electrode powder double layer on one side of the current collector. Claim 18 A dry electrode manufacturing method according to claim 15, wherein the step of providing the second film-formed electrode powder double layer on the other side of the current collector is characterized by the first film-formed electrode powder double layer being attached to the other side of the current collector after being provided on one side of the current collector. Claim 19 Electrode for a lithium secondary battery manufactured according to claim 12. Claim 20 A lithium secondary battery comprising an electrode for a lithium secondary battery according to claim 19.

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