Electrode coating die, electrode coating device, electrode manufacturing method, electrode, electrode assembly, and secondary battery

Abstract

The present invention provides an electrode coating die including a slurry discharger for discharging an active material slurry onto a current collector, and a dam liquid discharger provided on at least one side of the slurry discharger for discharging a dam liquid so as to form a dam layer covering at least a portion of an inclined surface provided on an edge of the active material slurry layer discharged and coated from the slurry discharger, and an electrode coating apparatus including the same.The present invention also provides a method for manufacturing an electrode including a step of preparing an active material slurry including an active material, a conductive material, and a solvent, and a coating step of applying the active material slurry onto a current collector, the coating step including a step of simultaneously discharging the active material slurry and the dam liquid onto the current collector to form a dam layer covering at least a portion of an inclined surface provided on an edge of at least one side of the active material slurry layer coated on the current collector to form an active material layer.

Description

[Technical Field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2021-0053323 filed with the Korean Intellectual Property Office on April 23, 2021, and Korean Patent Application No. 10-2022-0049992 filed with the Korean Intellectual Property Office on April 22, 2022, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to an electrode coating die, an electrode coating device, an electrode manufacturing method, an electrode, an electrode assembly, and a secondary battery. [Background technology]

[0003] Secondary batteries, which are highly adaptable to various products and have electrical properties such as high energy density, are widely used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) that are powered by electrical sources.

[0004] Such secondary batteries have the primary advantage of dramatically reducing the use of fossil fuels, as well as the advantage of not producing any by-products associated with energy use, and are therefore attracting attention as a new energy source that is environmentally friendly and improves energy efficiency.

[0005] In general, a lithium secondary battery is manufactured by coating a current collector with an active material slurry to manufacture an electrode, and then cutting a portion of the electrode so that the electrode has a desired shape.

[0006] If the ratio of the amount of active material coated on the positive and negative electrodes cannot be adjusted during the manufacturing process of such a battery, the safety of the secondary battery cannot be ensured. Therefore, a specific method is required to adjust the amount of active material coated in the step of coating the current collector with active material slurry. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent Publication No. 10-2013-0024766 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention provides an electrode coating die, an electrode coating apparatus, and an electrode manufacturing method that mitigate safety issues by controlling the amount of active material coated on the electrode.

[0009] Another object of the present invention is to provide the above-mentioned electrode, electrode assembly, and secondary battery.

[0010] However, the technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention below. [Means for solving the problem]

[0011] One embodiment of the present invention provides an electrode coating die including: a slurry discharge unit that discharges an active material slurry onto a current collector; and a dam liquid discharge unit that is provided on at least one side of the slurry discharge unit and discharges a dam liquid to form a dam layer that covers at least a portion of an inclined surface portion provided on an edge of the active material slurry layer discharged and coated from the slurry discharge unit.

[0012] Another embodiment of the present invention provides an electrode coating apparatus including: a transfer unit for continuously transferring a current collector of an electrode; and an electrode coating die according to the above-described embodiment for applying an active material layer to the current collector.

[0013] Another embodiment of the present invention provides a method for manufacturing an electrode, comprising: a step of preparing an active material slurry containing an active material, a conductive material, and a solvent; and a coating step of applying the active material slurry onto a current collector, wherein the coating step includes a step of simultaneously discharging the active material slurry and a dam liquid onto the current collector to form a dam layer that covers at least a portion of an inclined surface portion provided on at least one edge of the active material slurry layer coated on the current collector, thereby forming an active material layer.

[0014] Another embodiment of the present invention provides an electrode comprising a current collector and an active material layer provided on the current collector, wherein the active material layer comprises an inclined portion having a height of 80% or less of the height of its highest point, and a non-inclined portion having a height of more than 80% of the height of its highest point, and the length from the boundary between the non-inclined portion and the inclined portion to an end of the inclined portion is 40% or less of the total length of the non-inclined portion and the inclined portion combined.

[0015] Another embodiment of the present invention provides an electrode assembly in which a first electrode, a separator, and a second electrode are stacked and wound, wherein at least one of the first electrode and the second electrode is an electrode according to any of the above-described embodiments.

[0016] Another embodiment of the present invention provides a secondary battery including at least one electrode assembly according to the above embodiment. [Effects of the Invention]

[0017] When an electrode active material is coated on a current collector, a sliding section may be formed during the formation of an electrode assembly including the same, in which the mass of the active material in the negative electrode active material layer facing the positive electrode active material layer is reduced. This corresponding reduction in loading may cause negative electrode lithium to be precipitated all over the surface, which may result in safety issues such as explosion.

[0018] According to an embodiment of the present invention, in the case of electrode coating in which an electrode active material is applied to a current collector, particularly when a negative electrode active material slurry is applied to a current collector, the formation of a negative electrode sliding area that occurs when the negative electrode active material slurry is applied to the current collector can be minimized. Therefore, since the mass of the active material in the negative electrode active material layer facing the positive electrode active material layer is not reduced, safety issues that may occur due to an undesirable change in the loading ratio of the positive electrode active material to the negative electrode active material in that area can be eliminated.

[0019] By solving the above problems, the loading ratio of the positive and negative active materials included in the electrode assembly can be maintained, thereby eliminating safety issues and enabling a stable increase in the current applied to the battery, thereby enabling an increase in battery size, realizing high energy density, and reducing costs.

[0020] However, the advantageous effects that can be obtained by the present invention are not limited to the effects described above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the invention below. [Brief explanation of the drawings]

[0021] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention, and therefore the present invention should not be interpreted as being limited solely to the matters depicted in the drawings.

[0022] [Figure 1] 10 is a view schematically illustrating a configuration in which a first electrode and a second electrode included in an electrode assembly according to a comparative example of the present invention face each other. [Figure 2] FIG. 10 is a diagram showing a comparison between (a) the shape of the sloped portion of an active material layer coated using an existing electrode coating die according to a comparative example of the present invention and (b) the shape of the sloped portion of an active material layer coated using an electrode coating die according to an embodiment of the present invention. [Figure 3]1 is a diagram illustrating the internal structure of an electrode coating die according to an embodiment of the present invention. [Figure 4] FIG. 10 is a diagram showing (a) an active material slurry layer coated using an existing electrode coating die according to a comparative example of the present invention, and (b) a slurry layer and a dam layer coated using an electrode coating die according to an embodiment of the present invention. [Figure 5] 1A and 1B are schematic diagrams illustrating an electrode coating die according to an embodiment of the present invention. [Figure 6] 1A and 1B show an electrode coating die according to an embodiment of the present invention, in which FIG. 1A is an overall perspective view and FIG. 1B is an exploded perspective view. [Figure 7] 4 shows an electrode coating die according to an embodiment of the present invention, and shows the dotted line portion of FIG. 3 as a unit, where (a) is a front view, (b) is a cross-sectional view along line XX, and (c) is a bottom view. [Figure 8] FIG. 8 is a diagram showing an electrode coating die according to another embodiment of FIG. 7(b). [Figure 9] 3A and 3B are explanatory views showing how the active material slurry and dam liquid discharged from the electrode coating die according to the embodiment of the present invention are applied onto a current collector. [Figure 10] 1 is an explanatory diagram showing a state in which an active material layer is formed on a current collector using an electrode coating apparatus according to an embodiment of the present invention. [Figure 11] 1A and 1B show an electrode according to an embodiment of the present invention, in which FIG. 1A is an overall perspective view, and FIG. 1B is a perspective view of a cut electrode. DETAILED DESCRIPTION OF THE INVENTION

[0023] The terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best explain their inventions.

[0024] Throughout this specification, when a part "comprises" certain elements, this means that it may further include other elements, but not to the exclusion of other elements, unless otherwise specified.

[0025] Furthermore, terms such as "unit" and "device" used in the specification refer to a unit that processes at least one function or operation. Hereinafter, embodiments of the present invention will be described with reference to the drawings. Furthermore, throughout the specification, "A to B" means greater than or equal to A and less than or equal to B, and refers to a numerical range that includes both A and B.

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0027] One embodiment of the present invention provides an electrode coating die including: a slurry discharge unit 11 that discharges an active material slurry onto a current collector 30; and a dam liquid discharge unit provided on at least one side of the slurry discharge unit 11 and that discharges a dam liquid to form a dam layer 32 that covers at least a portion of an inclined surface portion 33 provided on an edge of an active material slurry layer 31 discharged and coated from the slurry discharge unit 11.

[0028] FIG. 1 is a diagram schematically illustrating a configuration in which a first electrode 1 and a second electrode 2 included in an electrode assembly according to a comparative example of the present invention face each other.

[0029] 1, the first electrode 1 may be a positive electrode or a negative electrode, and the second electrode 2 may have the opposite polarity to the first electrode (for example, the second electrode may be a negative electrode). During the formation of the electrode assembly, a slide section 5 may be formed in which the mass of the active material in the negative electrode active material layer facing the positive electrode active material layer decreases. This may result in a decrease in the loading of the negative electrode active material, leading to the entire precipitation of negative electrode lithium, which may cause a safety issue.

[0030] The slide section 5 refers to a section forming an inclined portion 41 where the mass of the active material applied to the end portion of the active material slurry layer 31 coated on the electrode current collector 30 is reduced and the thickness of the active material layer 40 is reduced compared to the non-inclined portion 42 of the active material layer.

[0031] According to one example, the inclined portion 41 is a portion having a height of 80% or less of the height of the highest point in the active material layer 40, and the non-inclined portion 42 is a portion having a height of more than 80% of the height of the highest point in the active material layer 40, and may be a portion of the active material layer 40 that does not have the inclined portion 41.

[0032] According to one embodiment of the present invention, the mass of the active material applied to the current collector 30 can be expressed as a loading amount, which can be expressed as an NP ratio value that compares the loading amounts of the positive and negative electrodes. The NP ratio value indicates the mass of the negative electrode active material relative to the mass of the positive electrode active material, and thus the ratio of the loading amounts of the positive electrode active material and the negative electrode active material can be known.

[0033] The NP ratio may be 100% to 120% and is calculated by multiplying the mass of the negative active material by 100% relative to the mass of the positive active material. If the NP ratio is less than 100%, a sliding section may be formed during electrode assembly formation, where the mass of the active material in the negative active material layer facing the positive active material layer decreases. This may result in a corresponding decrease in loading, leading to overall lithium deposition on the negative electrode, potentially resulting in safety issues such as explosions. If the NP ratio exceeds 120%, performance degradation may occur due to kinetic balance issues during charging and discharging of the negative and positive electrodes. The kinetic balance issue may occur due to differences in the lithium migration speeds during charging and discharging of the positive and negative electrodes. For example, this may occur when the rate at which lithium moves from the negative electrode to the positive electrode is slower than the rate at which lithium moves from the positive electrode to the negative electrode.

[0034] In one example, the NP ratio may be 100% or more, 103% or more, or 105% or more. The NP ratio may be 120% or less, 117% or less, 115% or less, 113% or less, or 112% or less. When these ranges are satisfied, the sliding area due to a decrease in loading of the negative electrode active material layer is reduced, thereby preventing safety issues.

[0035] The dam solution forms a dam layer 32 in the sliding section 5 of the active material slurry provided on the current collector 30 of the electrode so as to cover at least a portion of the inclined surface portion 33 provided on the edge of the active material slurry layer 31 coated on the current collector 30, thereby minimizing the formation of the sliding section 5 of the electrode.

[0036] The dam liquid discharge unit 12 for discharging the dam liquid may be provided on at least one side or both sides of the slurry discharge unit 11 for discharging the active material slurry in the electrode coating die. By providing the dam liquid discharge unit 12 on at least one side of the slurry discharge unit 11, a dam layer 32 may be formed on an inclined surface portion 33 provided on one or both sides of an edge of the active material slurry layer 31 discharged from the slurry discharge unit 11 and coated on the current collector 30. The portion where the inclined surface portion 33 is formed on the edge of the active material slurry coated on the current collector 30 may be included in the slide section 5.

[0037] By forming the dam layer 32 on the active material slurry layer 31, the mass of the active material in the negative electrode active material layer facing the positive electrode active material layer is not reduced, thereby eliminating safety issues that may occur due to an undesirable change in the loading ratio of the positive electrode active material and the negative electrode active material in that region.

[0038] The shape and size of the slurry discharge section 11 and the dam liquid discharge section 12 are not particularly limited as long as they discharge dam liquid so as to form a dam layer 32 that covers at least a portion of the inclined surface portion 33 provided on the edge of the active material slurry layer 31 discharged from the slurry discharge section and coated on the current collector 30.

[0039] FIG. 2 is a diagram comparing (a) the shape of the inclined portion of an active material layer coated using an existing electrode coating die according to a comparative example of the present invention and (b) the shape of the inclined portion 41 of an active material layer 40 coated using an electrode coating die 100 according to an embodiment of the present invention.

[0040] Referring to FIG. 2, when an electrode is coated using the electrode coating die 100 according to an embodiment of the present invention, a dam is formed in the area of ​​the slope where the active material loading amount is reduced, compared to when an electrode is coated using a conventional electrode coating die, thereby solving the problem associated with the reduced active material loading amount.

[0041] FIG. 3 is a diagram showing a schematic internal structure of an electrode coating die 100 according to an embodiment of the present invention, and FIG. 4 is a diagram showing (a) an active material slurry layer coated by an existing electrode coating die according to a comparative example of the present invention, and (b) a slurry layer 31 and a dam layer 32 coated by an electrode coating die according to an embodiment of the present invention.

[0042] 3 and 4, when an electrode is coated using an existing electrode coating die according to the comparative example of the present invention, a sliding section may be formed during the formation of an electrode assembly including the same, in which the mass of the active material in the negative electrode active material layer facing the positive electrode active material layer is reduced. This corresponding reduction in loading may cause negative electrode lithium to be precipitated all over the surface, resulting in safety issues such as explosions.

[0043] When coating an electrode using the electrode coating die 100 according to one embodiment of the present invention, a dam layer 32 is formed on the inclined surface portion 33 provided on the edge of the active material slurry layer 31 coated on the current collector 30, thereby preventing a decrease in the loading amount of the active material slurry of the electrode.

[0044] The electrode coating die 100 simultaneously discharges the active material slurry and the dam solution, and may form a dam layer 32 that covers at least a portion of the inclined surface portion 33 provided on the edge of the active material slurry layer 31 discharged from the slurry discharge portion 11 and coated on the current collector 30. The dam layer 32 may mitigate the sliding section 5 of the electrode and prevent a reduction in the loading amount of the active material slurry of the electrode, thereby minimizing safety issues.

[0045] The inclined surface portion 33 refers to a surface portion formed by the inclined portion in a section forming the inclined portion 41 where the thickness of the active material layer 40 is reduced compared to the central region of the active material layer 40. The inclined surface portion 33 may be a surface where the inclined portion 41 and the dam layer 32 contact each other.

[0046] FIG. 5 is a diagram schematically illustrating an electrode coating die 100 according to an embodiment of the present invention, and FIG. 6 illustrates the electrode coating die 100 according to an embodiment of the present invention, where (a) is an overall perspective view and (b) is an exploded perspective view.

[0047] FIG. 7 shows an electrode coating die 100 according to an embodiment of the present invention, and shows the dotted line portion of FIG. 3 as a unit, where (a) is a front view, (b) is a cross-sectional view along line AA, and (c) is a bottom view. FIG. 8 shows an electrode coating die according to another embodiment of FIG. 7(b).

[0048] 5 to 8, the device includes a shim 10 that separates the slurry discharge section 11 and the dam liquid discharge section 12; and a pair of support sections 20 arranged opposite each other on both sides of the shim 10, the shim 10 including a slurry passage section 14 that guides the active material slurry to the slurry discharge section 11, and a dam liquid passage section 15 that guides the dam liquid to the dam liquid discharge section 12, and the pair of support sections 20 including a first support section 21 arranged upstream in the coating direction C of the active material slurry, and a second support section 22 arranged downstream in the coating direction C.

[0049] The upstream side in the coating direction C of the active material slurry refers to the direction in which the active material slurry is first coated and then descends when the electrode current collector is continuously transported and coated with the active material slurry on the current collector. The downstream side in the coating direction C of the active material slurry refers to the direction in which the active material slurry is last coated and then descends when the electrode current collector is continuously transported and coated with the active material slurry on the current collector.

[0050] The shim 10 may be fixed by a pair of support parts 20 arranged opposite to each other on both sides, thereby providing the slurry discharge part 11 and the dam liquid discharge part 12 in the thickness direction of the shim 10. The shim 10 has a slurry passage part 14 for guiding the injected active material slurry, which extends to the slurry discharge part 11 to discharge the active material slurry. The shim also has a dam liquid passage part 15 for guiding the injected dam liquid, which extends to the dam liquid discharge part 12 to discharge the dam liquid simultaneously with the active material slurry.

[0051] Of the pair of support parts 20, the first support part 21 is arranged upstream of the coating direction C along the coating direction of the active material slurry, and the second support part 22 is arranged downstream of the coating direction C, thereby forming the slurry discharge part 11 and the dam liquid discharge part 12.

[0052] Referring to Figures 5 to 8, an electrode coating die 100 according to an embodiment of the present invention includes a shim 10 and a pair of support parts 20 facing both sides of the shim 10 to fix the shim 10, thereby forming the slurry discharge part 11 and the dam liquid discharge part 12.

[0053] According to one embodiment, the opening area 11D of the slurry discharge portion is wider than the opening area 12D of the dam liquid discharge portion, and the long width 11LW of the slurry discharge portion perpendicular to the coating direction of the active material slurry is wider than the long width 12LW of the dam liquid discharge portion.

[0054] The opening areas 11D and 12D of the slurry discharge portion and the dam liquid discharge portion mean the cross-sectional areas of the slurry discharge portion 11 and the dam liquid discharge portion 12 in the thickness direction of the shim 10, and the long widths 11LW and 12LW of the slurry discharge portion and the dam liquid discharge portion mean the lengths of the slurry discharge portion 11 and the dam liquid discharge portion 12 perpendicular to the coating direction of the active material slurry.

[0055] The major width 11LW of the slurry discharge portion is set wider than the major width 12LW of the dam liquid discharge portion. The major width 11LW of the slurry discharge portion may be 50 mm to 150 mm, 60 mm to 130 mm, or preferably 70 mm to 110 mm. According to one example, the major width 11LW of the slurry discharge portion may be 50 mm or more, 55 mm or more, 60 mm or more, 65 mm or more, or 70 mm or more. The major width 11LW of the slurry discharge portion may be 150 mm or less, 140 mm or less, 130 mm or less, 120 mm or less, 110 mm or less, or 100 mm or less.

[0056] The length 12LW of the dam liquid discharge portion may be 1 mm to 5 mm, 1 mm to 4.5 mm, 1 mm to 4 mm, 1 mm to 3.5 mm, or 1 mm to 3 mm. According to one example, the length 12LW of the dam liquid discharge portion may be 1 mm or more, or 1.5 mm or more. The length 12LW of the dam liquid discharge portion may be 5 mm or less, 4.5 mm or less, 4 mm or less, 3.5 mm or less, 3 mm or less, or 2.5 mm or less. When the length is within the above range, the sliding area due to reduced loading of the negative electrode active material layer is reduced, thereby preventing safety issues.

[0057] According to one embodiment, the active material slurry layer 31 includes a partition wall portion 13 provided between the slurry discharge portion 11 and the dam liquid discharge portion 12, and the partition wall portion 13 is configured to form a dam layer 32 that covers at least a portion of an inclined surface portion 33 provided at the edge portion of the active material slurry layer 31.

[0058] According to one embodiment, the partition wall portion 13 has a width perpendicular to the coating direction C of the active material slurry, and the width is 3% or less of the sum of the widths of the slurry discharge portion 11 and the dam liquid discharge portion 12. Maintaining the width is advantageous for forming the dam layer 32 that covers the inclined surface portion 33 provided on the edge of the active material slurry layer 31.

[0059] 7, the partition wall portion 13 may be provided on the shim 10. The partition wall portion 13 may be configured such that a width perpendicular to the coating direction of the active material slurry of the shim 10 provides a predetermined gap between the slurry discharge portion 11 and the dam liquid discharge portion 12, thereby forming a dam layer 32 that covers at least a portion of an inclined surface portion 33 of an active material slurry layer 31 formed by the active material slurry discharged onto the current collector 30 spreading in a direction perpendicular to the coating direction C.

[0060] Specifically, the width 13W of the partition wall portion may be 0.5 mm to 5 mm, 1 mm to 4.5 mm, 1.5 mm to 4.0 mm, or 2 mm to 3.5 mm. For example, the width 13W of the partition wall portion may be 0.5 mm or more, 1 mm or more, 1.5 mm or more, or 2 mm or more. The width 13W of the partition wall portion may be 5 mm or less, 4.5 mm or less, 4 mm or less, or 3.5 mm or less. The width 13W of the partition wall portion may be 3% or less, 2.5% or less, or 2% or less of the sum of the major width 11LW of the slurry discharge portion and the major width 12LW of the dam liquid discharge portion. The width may be maintained so as to form the dam layer 32 covering the inclined surface portion 33 provided at the edge of the active material slurry layer 31. According to one embodiment, the inclination angle A1 of the dam liquid passage portion 15 with respect to the long width 12LW of the dam liquid discharge portion is 90° or less. According to another example, the inclination angle A1 of the dam liquid passage portion 15 with respect to the long width 12LW of the dam liquid discharge portion may be 80° or less, 75° or less, 70° or less, 65° or less, or 60° or less. The inclination angle A1 of the dam liquid passage portion 15 with respect to the long width 12LW of the dam liquid discharge portion may be 30° or more, 35° or more, 40° or more, 45° or more, or 50° or more. Maintaining the inclination angle A1 is advantageous for forming the dam to cover the inclined surface portion A1 provided at the edge of the active material slurry.

[0061] Referring to Figures 7(b) to 8, the inclination angle A1 of the dam liquid passage portion 15 of the electrode coating die according to one embodiment of the present invention with respect to the direction of the long width 12LW of the dam liquid discharge portion may be 90° or less.

[0062] FIG. 9 is an explanatory view showing how the active material slurry and dam liquid discharged from the electrode coating die 100 according to the embodiment of the present invention are applied onto a current collector.

[0063] Referring to FIG. 9, the active material slurry and the dam solution discharged from the electrode coating die 100 according to an embodiment of the present invention are applied onto the current collector 30 in the coating direction C of the active material slurry, and a dam layer 32 can be formed that covers at least a portion of the inclined surface portion 33 provided at the edge of the active material slurry layer 31 that is formed by spreading in a direction perpendicular to the coating direction C.

[0064] Referring to Figures 7 and 9, in the cross-sectional views of the shim 10 in which the slurry discharge section 11 and the dam liquid discharge section 12 are partitioned, the dam liquid passage section 15 provided in the shim to discharge the dam liquid can form an inclination angle A1 with the long-width direction 12LWD of the dam liquid discharge section.

[0065] The longitudinal direction 12LWD of the dam liquid discharge portion means a direction perpendicular to the coating direction C of the active material slurry. The coating direction C of the active material slurry is a direction parallel to the direction in which the active material slurry is discharged from the electrode coating die 100 to coat the active material layer 40 on the current collector 30.

[0066] The form and shape of the dam liquid passage portion 15 are not particularly limited as long as it is connected to the dam liquid discharge portion, and it may be straight or curved.

[0067] The inclination angle A1 that the dam liquid passage section 15 makes with the long width 12LW direction of the dam liquid discharge section means the inclination angle A1 that the dam liquid passage section 15 makes with the long width 12LW direction of the dam liquid discharge section at the point where the dam liquid passage section 15 contacts the dam liquid discharge section 12. Adjusting the inclination angle A1 is advantageous for adjusting the inclination angle of the dam liquid discharge section 12 and forming the dam layer 32.

[0068] According to one embodiment, the dam liquid is the active material slurry. The dam liquid may have the same components as the active material slurry, or the composition may be different. When the dam liquid is the active material slurry, a dam layer 32 is formed to cover at least a portion of the inclined surface portion 33 provided at the edge of the active material slurry layer 31, thereby minimizing the formation of the negative electrode slide area 5 of the electrode. Since the mass of the active material of the electrode is not reduced, the loading ratio of the positive and negative electrode active materials in this area can be maintained.

[0069] According to one embodiment, a short width 12SW of the dam liquid discharge portion along the coating direction C of the active material slurry is equal to or smaller than a short width 11SW of the slurry discharge portion.

[0070] According to one embodiment, the position of the dam liquid discharge section 12 is provided in a straight line with the position of the slurry discharge section 11 or is provided offset to the downstream side of the coating direction C of the active material slurry, the short width 12SW of the dam liquid discharge section is smaller than the short width 11SW of the slurry discharge section, and the position of the dam liquid discharge section 12 is provided offset to the downstream side of the coating direction C of the active material slurry from the position of the slurry discharge section 11.

[0071] 7(c), the minor width 12SW of the dam liquid discharge portion along the coating direction C of the active material slurry may be the same as or smaller than the minor width 11SW of the slurry discharge portion. When the minor width 12SW of the dam liquid discharge portion is the same as the minor width 11SW of the slurry discharge portion, the position of the dam liquid discharge portion 12 may be aligned with the position of the slurry discharge portion 11 or may be offset toward the downstream side in the coating direction C of the active material slurry. When the minor width 12SW of the dam liquid discharge portion is smaller than the minor width 11SW of the slurry discharge portion, the position of the dam liquid discharge portion 12 may be offset toward the downstream side in the coating direction C of the active material slurry relative to the position of the slurry discharge portion 11.

[0072] When the position of the dam liquid discharge portion 12 is biased toward the downstream side of the coating direction C of the active material slurry, it is advantageous to form the dam to cover the inclined surface portion 33 provided at the edge of the active material slurry.

[0073] According to one embodiment, the dam liquid discharge portions 12 are provided on both sides of the slurry discharge portion 11. When the dam liquid discharge portions 12 are provided on both sides of the slurry discharge portion 11, the dam layers 32 can be formed on the inclined surface portions 33 provided on the edge portions on both sides of the active material slurry layer 31, respectively.

[0074] 3 and 4(b), there are a plurality of slurry discharge sections 11, and the dam liquid discharge sections 12 are provided on both sides of the slurry discharge section 11. The dam liquid discharge sections 12 include a first dam liquid discharge section 121 connected from the dam liquid passage section 15 between two adjacent slurry discharge sections 11 and provided as two separate discharge sections, and a second dam liquid discharge section 122 connected from the dam liquid passage section 15 at the outermost side of the plurality of slurry discharge sections and provided as a single discharge section.

[0075] The slurry discharge unit 11 may be plural or singular. For example, the number of the slurry discharge units 11 may be 1 or more, 2 or more, 3 or more, 4 or more, or 5 or more. The number of the slurry discharge units 11 may be 10 or less, or 9 or less. According to an embodiment of the present invention, the number of the slurry discharge units 11 may be 7 to 9. The number of the slurry discharge units 11 may be variously set depending on the electrode coating process and is not limited to the above range.

[0076] The dam liquid discharge part 12 may be provided on both sides of the slurry discharge part 11 and may include a first dam liquid discharge part 121 and a second dam liquid discharge part 122 .

[0077] The first dam liquid discharge part 121 includes two discharge parts 121 through which the dam liquid injected into the dam liquid injection part 17 of the electrode coating die 100 extends to the dam liquid passage part 15 and is discharged, and is provided between two adjacent slurry discharge parts 11, and can form dam layers 32 on different active material layers 40 formed adjacent to each other.

[0078] When the number of the slurry discharge sections 11 is n, the number of the first dam liquid discharge sections 121 is 2(n-1), where n is an integer from 1 to 10. For example, depending on the number of the slurry discharge sections 11, the number of the first dam liquid discharge sections 121 may be 0 to 18, 2 to 16, 4 to 14, 6 to 12, or 12 to 16. According to one embodiment of the present invention, the number of the first dam liquid discharge sections 121 may be 7 to 9.

[0079] The second dam liquid discharge portion 122 may include one discharge portion 122 facing the active material layer 40 at the outermost side of the slurry discharge portion 11, and therefore may be two.

[0080] According to one embodiment, the two discharge portions included in adjacent first dam liquid discharge portions 121 are spaced apart from each other to form a non-coated portion 34 on the current collector where the active material layer 40 is not provided.

[0081] Two discharge portions included in adjacent first dam liquid discharge portions 121 are provided between two adjacent slurry discharge portions 11, and may form dam layers 32 on adjacently formed different active material layers 40. Adjacently formed different active material layers 40 on one current collector 30 may form uncoated portions 34 therebetween where the active material slurry is not coated, and the uncoated portions 34 are advantageous for forming tabs that are electrically connected to electrode terminals when forming an electrode assembly of an electrode including the uncoated portions 34.

[0082] 3 to 4(b), there may be a plurality of slurry discharge portions 11, and the dam liquid discharge portions 12 may be provided on both sides of the slurry discharge portion 11. The first dam liquid discharge portion 121 may be divided into two discharge portions between two adjacent slurry discharge portions 11, and may be connected to the dam liquid passage portion 15. The second dam liquid discharge portion 122 may be provided as a single discharge portion at the outermost side of the plurality of slurry discharge portions 11, and may be connected to the dam liquid passage portion 15.

[0083] The active material slurry may be discharged from the plurality of slurry dischargers 11 onto the current collector 30 in a coating direction C of the active material slurry to form an active material layer 40, the dam liquid may be discharged from the first dam liquid discharger 121 provided between the plurality of slurry dischargers 11 to form a dam layer 32 on the inclined surface portion provided on the edge of each adjacent active material layer 40, and the dam liquid may be discharged from the second dam liquid discharger 122 provided on both outermost sides of the plurality of slurry dischargers 11 to form a dam layer 32 on the inclined surface portion 33 provided on the edge of the active material layer formed on both outermost sides of the current collector 30.

[0084] Electrode coating that can form multiple active material layers 40 on one current collector 30 is possible through the multiple slurry dischargers 11, the first dam liquid discharger 121, and the second dam liquid discharger 122, and the loading amount of the active material of the electrode included in the electrode assembly can be adjusted more economically. As a result, safety issues can be resolved, the current applied to the battery can be stably increased, the battery size can be increased, and high energy density and cost reductions can be achieved.

[0085] According to one embodiment, the second support portion 22 further includes a dam liquid injection portion 17 for injecting the dam liquid into the dam liquid passage portion 15, and the first support portion 21 further includes a slurry injection portion 16 for injecting the active material slurry into the slurry passage portion 14.

[0086] 5 to 7, the dam liquid injector 17 is connected to the dam liquid passage 15 and the dam liquid discharger 12, and can discharge the injected dam liquid. The slurry injector 16 is connected to the slurry passage 14 and the slurry discharger 11, and can discharge the injected active material slurry.

[0087] Another embodiment of the present invention provides an electrode coating apparatus 200 including a transfer unit 210 for continuously transferring an electrode current collector 30, and an electrode coating die 100 according to the above-described embodiment for applying an active material layer 40 to the current collector 30.

[0088] The transfer unit 210 may include a roller for continuously transferring the current collector 30 of the electrode. The roller may rotate in a coating direction C of the active material slurry to be coated on the current collector 30 to continuously transfer the current collector 30. The speed of the roller may be adjusted to form the active material layer 40 and the dam layer 32 on the current collector 30.

[0089] FIG. 10 is an explanatory diagram showing the formation of an active material layer 40 on a current collector 30 using an electrode coating apparatus 200 according to an embodiment of the present invention.

[0090] 10, the transfer unit 210 continuously transfers the electrode current collector 30, and the active material slurry and the dam liquid discharged from the electrode coating die 100 according to the above-described embodiment are discharged onto the transferred current collector 30 to form the active material layer 40. The electrode coating capable of forming the active material layer 40 on the current collector 30 can be performed by simultaneously coating multiple electrodes using multiple slurry dischargers 11 and dam liquid dischargers 12. This makes it possible to more economically adjust the loading amount of the active material of the electrodes included in the electrode assembly.

[0091] Another embodiment of the present invention provides a method for manufacturing an electrode, comprising: a step of preparing an active material slurry containing an active material, a conductive material, and a solvent; and a coating step of applying the active material slurry onto a current collector 30, wherein the coating step includes a step of simultaneously discharging the active material slurry and a dam liquid onto the current collector 30 to form a dam layer 32 that covers at least a portion of an inclined surface portion 33 provided on at least one edge of the active material slurry layer 31 coated on the current collector, thereby forming an active material layer 40.

[0092] The coating step is not particularly limited as long as it includes a step of discharging the active material slurry onto the current collector 30 and simultaneously discharging a dam liquid to form a dam layer 32 that covers at least a portion of an inclined surface portion 33 provided on at least one edge of the active material slurry layer 31 coated on the current collector, thereby forming an active material layer 40.

[0093] According to one embodiment, there is provided a method for manufacturing an electrode, which includes a step of preparing an active material slurry containing an active material, a conductive material, and a solvent, and a coating step of applying the active material slurry onto a current collector, wherein the coating step uses an electrode coating die 100 according to the above-described embodiment to simultaneously discharge the active material slurry onto the current collector 30 and a dam liquid so as to form a dam layer 32 that covers at least a portion of an inclined surface portion 33 provided on at least one edge of the active material slurry layer 31 coated on the current collector 30, thereby forming an active material layer 40.

[0094] Referring to FIG. 10, the coating step of applying the active material slurry and the dam liquid prepared in the active material slurry preparation step onto the current collector 30 may include a step of simultaneously ejecting the active material slurry and the dam liquid to form a dam layer 32 covering at least a portion of the inclined surface portion 33 provided on at least one edge of the active material slurry layer 31 to form an active material layer 40, and this step may include a step of forming the active material layer 40 from the electrode coating die 100 according to the above-described embodiment.

[0095] According to the coating step, a dam is formed in the sliding section 5 of the active material slurry coated by a conventional coating method, thereby alleviating the sliding section 5 of the electrode active material slurry, thereby preventing a decrease in the loading amount of the electrode active material and resolving stability issues.

[0096] According to one embodiment, the dam liquid may have the same viscosity as the active material slurry, or may have a lower or higher viscosity than the active material slurry.

[0097] The dam liquid may be the active material slurry, and may have the same components as the active material slurry or a different composition. The dam liquid may have the same viscosity, a lower viscosity, or a higher viscosity than the active material slurry. The viscosity range of the dam liquid may be adjusted to be advantageous for forming the dam covering the inclined surface portion 33 provided at the edge of the active material slurry, and may be adjusted depending on the electrode coating process.

[0098] According to one embodiment, the method for manufacturing an electrode may include a drying step of drying the active material layer 40 after the coating step, or may further include a slitting step of cutting the electrode manufactured by the method for manufacturing an electrode in the coating direction C of the active material slurry.

[0099] The drying step may be a step of drying the active material layer 40 after the coating step, or a coating step of coating the active material layer 40 on the opposite side of the current collector 30 and the drying step may be further performed after the drying step.

[0100] The electrode manufactured by the method for manufacturing an electrode may further include a slitting step of cutting the electrode in a coating direction C of the active material slurry.

[0101] The slitting step may include cutting the active material layers 40 formed on one current collector 30 in the electrode so as to provide the uncoated portions 34 at the edges thereof.

[0102] Furthermore, a step of cutting the active material layer 40 provided on the electrode in a coating direction C of the active material slurry may be included, and by cutting, an active material layer 40 having a dam layer 32 formed on only one side of the electrode, the dam layer 32 covering at least a portion of the inclined surface portion 33 of the active material slurry layer 31, may be provided. This can economically solve the battery safety problem associated with the mass of the active material, and the current applied to the battery can be stably increased, thereby allowing the battery size to be increased.

[0103] The slitting step may be performed from a midpoint in the width direction of the current collector 30 forming the active material layer 40 in the coating direction C of the active material slurry, i.e., in the length direction of the current collector. The cutting point may be the midpoint or another point in the width direction of the current collector where the active material layer 40 is formed.

[0104] Furthermore, depending on the application of the electrode assembly, cutting can also be performed in a direction perpendicular to the coating direction C, that is, in the width direction of the current collector.

[0105] Another embodiment of the present invention provides an electrode including a current collector 30 and an active material layer 40 provided on the current collector, wherein the active material layer 40 includes an inclined portion 41 having a height of 80% or less of the height of its highest point, and a non-inclined portion 42 having a height of more than 80% of the height of its highest point, and the length from the boundary between the non-inclined portion 42 and the inclined portion 41 to the end of the inclined portion 41 is 40% or less of the total length of the non-inclined portion 42 and the inclined portion 41 combined.

[0106] The inclined portion 41 refers to a portion where the thickness decreases at the edge of the active material layer 40 coated on the current collector 30, and refers to a portion having a height of 80% or less of the height at the highest point in the thickness of the active material layer 40. The non-inclined portion 42 refers to a portion having a height of more than 80% of the height at the highest point in the thickness of the active material layer 40.

[0107] The inclined portion 41 refers to an inclined portion at the edge of the active material layer, and the non-inclined portion 42 refers to a central portion provided between the inclined portions of the active material layer. Even if the non-inclined portion 42 includes an inclined structure in more than a portion thereof, in this specification, the inclined portion 41 and the non-inclined portion 42 are described separately based on 80% of the height of the highest point in the thickness of the active material layer 40.

[0108] The active material layer 40 includes a non-inclined portion 42 that does not have the inclined portion 41, and the length from the boundary between the non-inclined portion 42 and the inclined portion 41 to the end of the inclined portion 41 is the inclined portion length 41L, which means the length corresponding to the portion where the thickness decreases at the edge of the active material layer 40, and this may be included in the sliding section 5 of the electrode.

[0109] The total length of the active material layer 40 is the length of the active material layer perpendicular to the coating direction C of the active material slurry, and means the sum of the length 42L of the non-inclined portion and the length 41L of the inclined portion.

[0110] According to one embodiment, the length 41L from the boundary between the non-inclined portion and the inclined portion to the end of the inclined portion may be 40% or less, 35% or less, or 30% or less of the entire length of the active material layer. The length 41L from the boundary between the non-inclined portion and the inclined portion to the end of the inclined portion may be 15% or more, 20% or more, or 25% or more of the entire length of the active material layer.

[0111] 11 shows an electrode according to an embodiment of the present invention, where (a) is an overall perspective view and (b) is a perspective view of a cut electrode. Referring to FIG. 11, the electrode includes a current collector 30 and an active material layer 40 provided on the current collector. The active material layer includes the inclined portion 41 and the non-inclined portion 42. For example, in one embodiment, the electrode may have a length 41L from the boundary between the non-inclined portion and the inclined portion to the end of the inclined portion, which is 40% or less of the overall length.

[0112] The electrode may be manufactured by performing the coating step and / or the drying step using the slurry manufactured by the active material slurry manufacturing step. The electrode may be cut in the coating direction C of the active material slurry by the slitting step. Therefore, it is possible to manufacture an electrode that allows for more economical adjustment of the loading amount of the active material of the electrode included in the electrode assembly.

[0113] According to one embodiment, an electrode including a current collector 30 and an active material layer 40 provided on the current collector has an inclined portion 41 having a height of 80% or less of the height of the highest point, and a non-inclined portion 42 having a height of more than 80% of the height of the highest point, and an inclination angle A2 formed by a tangent to the current collector at the boundary between the non-inclined portion and the inclined portion is 25° or more.

[0114] Referring to FIG. 2(b), the inclination angle A2 formed by the tangent to the current collector at the boundary between the non-inclined portion and the inclined portion refers to the angle formed by the tangent to the current collector 30 at a portion where the thickness begins to decrease at the edge of the active material layer 40, preferably at a portion having a height that is 80% of the height of the highest point of the active material layer 40.

[0115] The active material layer 40 includes a dam layer 32 that covers at least a portion of the inclined surface portion 33 provided at the edge of the active material slurry layer 31 coated on the current collector. The amount of active material coated on the electrode is adjusted by the dam layer 32, and the angle A2 formed with the current collector at the portion where the inclined portion 41 begins from the non-inclined portion 42 may be larger than that of existing active material slurry layers.

[0116] The angle may refer to the inclination of a tangent to the current collector 30 at the portion where the inclined portion 41 begins from the non-inclined portion 42, and the inclination refers to the inclination of a tangent to the active material layer 40 at the portion where the inclined portion 41 begins from the non-inclined portion 42. The inclination of the boundary between the non-inclined portion 42 and the inclined portion 41 in the electrode according to this embodiment may be larger than the inclination in a conventional electrode.

[0117] The inclination angle A2 formed by a tangent to the current collector at the boundary between the non-inclined portion and the inclined portion may be 25° or more, or 30° or more. The inclination angle A2 formed by a tangent to the current collector at the boundary between the non-inclined portion and the inclined portion may be 80° or less, 75° or less, 70° or less, or 65° or less. When this range is satisfied, the mass of the active material in the second electrode 2 active material layer facing the first electrode 1 active material layer does not decrease, thereby eliminating safety issues that may arise due to undesirable changes in the loading ratio of the positive and negative electrode active materials.

[0118] Referring to FIG. 2(b), an electrode including a current collector 30 and an active material layer 40 provided on the current collector 30 has an inclined portion 41 having a height of 80% or less of the height of the highest point of the active material layer 40, and a non-inclined portion 42 having a height of more than 80% of the height of the highest point of the active material layer 40, and the inclination angle A3 formed by a tangent line at the end of the inclined portion 41 and the current collector 30 is 25° or more.

[0119] According to one embodiment, the inclination angle A3 formed by a tangent line to the current collector at the end of the inclined portion may be 25° or more, 30° or more, 35° or more, 40° or more, or 45° or more. The inclination angle A3 formed by a tangent line to the current collector at the end of the inclined portion may be 90° or less, 85° or less, or 80° or less.

[0120] The end of the inclined portion 41 may refer to the end of the sliding section 5 of the electrode, and since the electrode according to one embodiment of the present invention has an active material layer 40 that forms a dam, the loading amount of the active material slurry is large, so the inclination angle A3 at the end point of the inclined portion can be formed larger than the inclination angle of existing electrodes.

[0121] The inclination angle A3 may refer to the inclination of a tangent line at an end of the inclined portion 41 to the current collector 30, and the inclination refers to the inclination of a tangent line that contacts the active material layer 40 at the end of the inclined portion 41. The inclination of the inclined portion 41 at the end of the inclined portion 41 to the current collector 30 in the electrode according to this embodiment may be larger than the inclination in a conventional electrode.

[0122] Therefore, the mass of the active material in the second electrode 2 active material layer facing the first electrode 1 active material layer does not decrease, which eliminates safety issues that may arise due to an undesirable change in the loading ratio of the positive and negative electrode active materials.

[0123] According to one embodiment, an electrode including a current collector 30 and an active material layer 40 provided on the current collector 30 has an inclined portion 41 having a height of 80% or less of the height of its highest point, and a non-inclined portion 42 having a height of more than 80% of the height of its highest point, and the inclination of a line connecting the boundary point between the non-inclined portion 42 and the inclined portion 41 and the end point of the inclined portion 41 with the current collector 30 by the shortest distance is 0.8 or more.

[0124] According to one embodiment, the slope of a line connecting the boundary between the non-inclined portion 42 and the inclined portion 41 and an end point of the inclined portion 41 at the shortest distance to the current collector 30 may be 0.8 or more, 1 or more, 1.5 or more, 2 or more, 2.5 or more, 3 or more, 3.5 or more, 4 or more, 4.5 or more, 5 or more, or 5.5 or more. The slope of a line connecting the boundary between the non-inclined portion 42 and the inclined portion 41 and an end point of the inclined portion 41 at the shortest distance to the current collector 30 may be 10 or less, 9.5 or less, 9 or less, 8.5 or less, 8 or less, 7.5 or less, 7 or less, 6.5 or less, or 6 or less. When the slope of the line is within the above range, the mass of the active material in the second electrode 2 active material layer facing the first electrode 1 active material layer is not reduced, thereby eliminating safety issues that may occur due to an undesirable change in the loading ratio of the positive and negative electrode active materials.

[0125] The boundary between the non-inclined portion 42 and the inclined portion 41 and the end of the inclined portion 41 may be included in a slide section 5 where the thickness decreases at the edge of the active material layer 40 to form the inclined portion 41. Since an electrode including the active material layer 40 forms a dam and increases the loading amount of active material slurry compared to conventional electrodes, the inclination of the inclined portion 41 of the active material layer 40 may be greater than the inclination of conventional electrodes.

[0126] The inclination may be the inclination of a line connecting the boundary point between the non-inclined portion 42 and the inclined portion 41 and the end point of the inclined portion 41 at the shortest distance with the current collector 30 .

[0127] The slope can be measured as the height H of the active material layer relative to the length I from the perpendicular boundary point between the non-inclined portion and the inclined portion to the end of the inclined portion in the current collector 30, and can satisfy the following formula 2. The length I from the perpendicular boundary point between the non-inclined portion and the inclined portion to the end of the inclined portion in the current collector 30 may be the length 41L of the inclined portion.

[0128] According to an example, the gradient from the boundary point between the non-inclined portion 42 and the inclined portion 41 to the end of the inclined portion 41 may satisfy the following formula 2.

[0129] [Formula 2] H / I≧0.8 In the above formula 2, H may be the height of the active material layer 40, and I may be the length from the perpendicular point at the boundary between the non-inclined portion and the inclined portion of the current collector 30 to the end of the inclined portion.

[0130] Since an electrode including the active material layer 40 forms a dam and increases the loading amount of active material slurry compared to conventional electrodes, the slope of the sloped portion of the active material layer 40 may be greater than the slope of conventional electrodes.

[0131] When this range is satisfied, the mass of the active material in the second electrode 2 active material layer facing the first electrode 1 active material layer does not decrease, thereby eliminating safety issues that may arise due to an undesirable change in the loading ratio of the positive and negative electrode active materials.

[0132] According to one embodiment, an electrode including a current collector 30 and an active material layer 40 provided on the current collector 30 includes an active material slurry layer 31 coated on the current collector 30, and a dam layer 32 covering at least a portion of an inclined surface portion 33 provided on the edge of the active material slurry layer, and the dam layer 32 is provided to cover 1% to 20% of the entire surface of the active material slurry layer 31.

[0133] The inclined surface portion 33 refers to a surface portion formed by the inclined portion in a section forming the inclined portion 41 where the thickness of the active material layer 40 is reduced compared to the central region of the active material layer 40. The inclined surface portion 33 may be a surface where the inclined portion 41 and the dam layer 32 contact each other.

[0134] According to one embodiment, the area covered by the dam layer 32 may be 1% or more, 3% or more, 5% or more, or 8% or more of the entire surface of the active material slurry layer 31. The area covered by the dam layer may be 20% or less, 18% or less, 15% or less, or 12% or less of the entire surface of the active material slurry layer.

[0135] When the above range is satisfied, the loading amount of the active material slurry increases, and the active material layer 40 including the dam layer 32 can be formed in the active material slurry layer 31. Furthermore, the mass of the active material in the electrode active material layer 40 does not decrease, which is advantageous in eliminating safety issues.

[0136] According to one embodiment, an electrode including a current collector 30 and an active material layer 40 provided on the current collector 30 is prepared by the method for manufacturing an electrode according to the above-described embodiment.

[0137] Referring to FIG. 2(b), when an electrode is manufactured according to an embodiment of the present invention, compared to conventional electrodes, a dam is formed in the region where the active material loading amount is reduced along the sliding section 5 of the active material slurry generated at the edge of the electrode, thereby solving the problem associated with the reduced active material loading amount.

[0138] According to one embodiment, the edge of the current collector 30 includes an uncoated portion 34 where the active material layer 40 is not provided, and the inclined portion 41 is formed in the boundary region between the active material layer 40 and the uncoated portion 34.

[0139] The inclined portion 41 may be formed at the end portion where the active material layer 40 is applied, and may be formed in the boundary region of the uncoated portion 34 .

[0140] Another embodiment of the present invention provides an electrode assembly in which a first electrode, a separator, and a second electrode are stacked and wound, wherein at least one of the first electrode and the second electrode is an electrode according to any of the above-described embodiments.

[0141] According to one embodiment, in the electrode assembly, the first electrode is a positive electrode, the second electrode is a negative electrode, and the mass ratio of the active material layers of the first electrode and the second electrode satisfies the following formula 1:

[0142] [Formula 1] 100(%)≦X2 / X1≦120% In the above formula 1, X1 is the mass of the active material layer 40 in the first electrode, and X2 is the mass of the active material layer 40 in the first electrode.

[0143] The mass ratio of the active material layer 40 may be 100% to 120%, which can be expressed by multiplying the mass of the active material of the second electrode 2 by 100% relative to the mass of the active material of the first electrode 1. If the mass ratio of the active material layer 40 is less than 100%, a slide section 5 may be formed during the formation of the electrode assembly, where the mass of the active material of the second electrode 2 active material layer facing the first electrode 1 active material layer decreases. This may result in a corresponding decrease in loading, resulting in the full deposition of lithium on the negative electrode, leading to safety issues such as explosions. If the mass ratio of the active material layer 40 exceeds 120%, performance degradation may occur due to a kinetic balance problem during charge and discharge of the negative and positive electrodes. The kinetic balance problem may occur due to a difference in the lithium migration rate during charge and discharge between the positive and negative electrodes. For example, this may occur when the rate at which lithium moves from the negative electrode to the positive electrode is slower than the rate at which lithium moves from the positive electrode to the negative electrode.

[0144] For example, the mass ratio of the active material layer 40 may be 100% or more, 103% or more, or 105% or more. The mass ratio of the active material layer 40 may be 120% or less, 117% or less, 115% or less, 113% or less, or 112% or less. When this range is satisfied, the mass of the active material in the second electrode 2 active material layer facing the first electrode 1 active material layer does not decrease, thereby eliminating safety issues that may arise due to undesirable changes in the loading ratio of the positive and negative electrode active materials.

[0145] According to one embodiment, the second electrode is a negative electrode, which may be an electrode according to the above-described embodiment. In this case, the formation of a negative electrode slide area that occurs when applying a negative electrode active material slurry to a current collector can be minimized. Therefore, the mass of the active material in the negative electrode active material layer facing the positive electrode active material layer is not reduced, thereby eliminating safety issues that may arise due to an undesirable change in the loading ratio of the positive electrode active material and the negative electrode active material in that region. By resolving these issues, the loading ratio of the positive and negative electrode active materials included in the electrode assembly can be maintained, thereby eliminating safety issues and enabling a stable increase in the current applied to the battery.

[0146] According to one embodiment, the inclined portions 41 or inclined surfaces 33 provided on one side of the first electrode 1 and the second electrode 2 are provided in opposite directions. In this case, the mass of the active material in the active material layer of the second electrode 2 facing the active material layer of the first electrode 1 is not reduced, thereby eliminating safety issues that may occur due to an undesirable change in the loading ratio of the positive and negative active materials.

[0147] According to one embodiment, the first electrode 1 is a positive electrode and the second electrode 2 is a negative electrode. When the second electrode 2 is a negative electrode, the formation of the negative electrode slide section 5 can be minimized according to an embodiment of the present invention. As a result, the mass of the active material in the negative electrode active material layer facing the positive electrode active material layer is not reduced, which prevents an undesirable change in the loading ratio of the positive electrode active material to the negative electrode active material in that region, thereby preventing full-surface deposition of lithium in the negative electrode and eliminating safety issues.

[0148] Another embodiment of the present invention provides a secondary battery including at least one electrode assembly according to the above embodiment.

[0149] According to one embodiment, the secondary battery may include an electrode assembly, a battery can, a seal, and a terminal.

[0150] In the electrode assembly, the first electrode 1 may be a positive electrode or a negative electrode, and the second electrode 2 corresponds to an electrode having the opposite polarity to the first electrode. The first electrode 1 and the second electrode 2 may have a sheet shape. The electrode assembly may have, for example, a jellyroll shape. That is, the electrode assembly may be manufactured by sequentially stacking the first electrode 1, a separator, the second electrode 2, and a separator at least once, and winding the stack around the winding center. In this case, an additional separator may be provided on the outer periphery of the electrode assembly for insulation from the battery can.

[0151] Meanwhile, in the present invention, the positive electrode active material coated on the positive electrode current collector and the negative electrode active material coated on the negative electrode current collector may be any active material known in the art without any limitation.

[0152] In one example, the positive electrode active material has the general chemical formula A[A x M y ]O 2+z(A includes at least one element selected from Li, Na, and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≧0, 1≦x+y≦2, −0.1≦z≦2; and the stoichiometric coefficients of the components included in x, y, z, and M are selected to maintain electroneutrality of the compound).

[0153] In another example, the positive electrode active material is an alkali metal compound xLiM as disclosed in US Pat. No. 6,677,082, US Pat. No. 6,680,143, etc. 1 O2-(1-x)Li2M 2 O3(M 1 contains at least one element having an average oxidation state of 3; M 2 may contain at least one element having an average oxidation state of 4; 0≦x≦1).

[0154] In still another example, the positive electrode active material has the general chemical formula LiM 1 xFe1-xM 2 yP1-yM 3 zO 4-z (M 1 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, and Al; M 2 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V, and S; M 3 contains halogen elements, optionally including F; 0 <a≦2、0≦x≦1、0≦y<1、0≦z<1;a、x、y、z、M 1 , M 2 , and M 3wherein the stoichiometric coefficients of the components included are selected to maintain electroneutrality of the compound), or lithium metal phosphate represented by Li3M2(PO4)3, where M comprises at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and Al.

[0155] Preferably, the positive electrode active material can contain primary particles and / or secondary particles formed by aggregation of primary particles.

[0156] For example, the negative electrode active material may be a carbon material, lithium metal or a lithium metal compound, silicon or a silicon compound, or tin or a tin compound. Metal oxides with a potential of less than 2 V, such as TiO2 and SnO2, may also be used as the negative electrode active material. The carbon material may be either low-crystalline carbon or high-crystalline carbon.

[0157] The separator may be a porous polymer film, for example, a porous polymer film made from a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., either alone or in combination. As another example, the separator may be a conventional porous nonwoven fabric, for example, a nonwoven fabric made from high-melting-point glass fiber, polyethylene terephthalate fiber, etc.

[0158] At least one surface of the separator may include a coating layer of inorganic particles.

[0159] Alternatively, the separator itself may be made of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound with a binder so that there is an interstitial volume between adjacent particles.

[0160] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or more. Non-limiting examples of the inorganic particles include Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg3Nb 2 / 3 )O3-PbTiO3 (PMN-PT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0161] The electrolyte is A + B - The salt may have the following structure: + Li + , Na + , K. + and alkali metal cations such as B - is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , BF2C2O4 - , BC4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO- , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - , and (CF3CF2SO2)2N - The anion comprises at least one anion selected from the group consisting of:

[0162] The electrolyte can be dissolved in an organic solvent, such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or a mixture thereof.

[0163] In one example, the secondary battery may include a battery can that houses the electrode assembly. The battery can may be cylindrical, with a circular diameter at both ends of 30 mm to 55 mm and a height of 60 mm to 120 mm. For example, the circular diameter x height of the cylindrical battery can may be 46 mm x 60 mm, 46 mm x 80 mm, 46 mm x 90 mm, or 46 mm x 120 mm. The secondary battery may be a battery cell.

[0164] Preferably, the battery cell may be, for example, a battery cell having a form factor ratio (defined as the diameter of the battery cell divided by its height, i.e., the ratio of height (H) to diameter (Φ)) greater than about 0.4.

[0165] Here, the form factor refers to a value indicating the diameter and height of a battery cell. Battery cells according to an embodiment of the present invention may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, a 46800 cell, or a 46900 cell. In the form factor value, the first two digits indicate the diameter of the cell, the next two digits indicate the height of the cell, and the final digit 0 indicates that the cell has a circular cross section.

[0166] A battery cell according to one embodiment of the present invention may be a substantially cylindrical cell having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of about 0.418.

[0167] Another embodiment of the battery cell may be a generally cylindrical cell having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of about 0.640.

[0168] A battery cell according to another embodiment may be a substantially cylindrical cell having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of about 0.418.

[0169] In yet another embodiment, the battery cell may be a substantially cylindrical cell having a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of approximately 0.600.

[0170] In yet another embodiment, the battery cell may be a substantially cylindrical cell having a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of approximately 0.575.

[0171] A battery cell according to yet another embodiment may be a cylindrical battery cell having a substantially cylindrical shape with a diameter of about 46 mm, a height of about 90 mm, and a form factor ratio of 0.511.

[0172] Although the present invention has been described above based on limited embodiments and drawings, it goes without saying that the present invention is not limited thereto, and that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims described below. [Explanation of symbols]

[0173] 1...1st electrode 2...Second electrode 3, 3' Tab section 4. Insulation coating 5. Slide section 100 ··· Electrode coating die 10. Shim 11 Slurry discharge section 11D: Opening area of ​​slurry discharge section 11LW: Length of the slurry discharge section 11SW: Short width of slurry discharge section 12 Dam liquid discharge section 12D: Opening area of ​​the dam liquid discharge section 12LW: Length and width of the dam liquid discharge section 12SW: Short width of dam liquid discharge section 121 First dam liquid discharge section 122 Second dam liquid discharge section 13...Bulkhead part 13W: Width of the partition 14 Slurry passage 15 Dam liquid passage 16 Slurry injection section 17 Dam liquid injection section 20...Support part 21...1st support part 22...Second support part A1: The angle of inclination (θ) of the dam liquid passage to the longitudinal direction of the dam liquid discharge section A2: The angle of inclination (θ) between the tangent and the current collector at the boundary between the non-inclined and inclined sections A3: The angle of inclination (θ) between the tangent and the current collector at the end of the inclined section 30 Current collector 31 Active material slurry layer 32 Dam Layer 33...Slope section 34 Plain area 40...Active material layer 41...Slope part 41L: Length of the inclined section 42 Non-inclined section 42L: Length of non-inclined section 150 ··· Active material slurry tank 151 Dam liquid tank 152, 153 Transfer pump 154, 155 Transfer piping 200 Electrode coating equipment 210 Transfer unit 220...Drying equipment C: Coating direction of active material slurry 12LWD: Longitudinal direction of the dam liquid discharge section 12SWD: Short width direction of dam liquid discharge section

Claims

1. a slurry discharge unit that discharges an active material slurry onto the current collector; and a dam liquid discharge part provided at least on one side of the slurry discharge part, and discharging a dam liquid to form a dam layer covering at least a part of an inclined surface part provided at an edge of the active material slurry layer discharged and coated from the slurry discharge part; In an electrode coating die comprising: A plurality of the slurry discharge portions are provided, and the dam liquid discharge portions are provided on both sides of each of the slurry discharge portions, the dam liquid discharge section includes a first dam liquid discharge section consisting of two discharge sections between two adjacent slurry discharge sections, and a second dam liquid discharge section consisting of one discharge section at the outermost side of the plurality of slurry discharge sections, the two discharge portions of the first dam liquid discharge portion are spaced apart from each other to form a non-coated portion on the current collector where no active material layer is provided, The dam liquid is the active material slurry.

2. a shim that separates the slurry discharge portion and the dam liquid discharge portion; and The electrode coating die of claim 1 , further comprising a pair of supports disposed oppositely on opposite sides of the shim.

3. the shim includes a slurry passage portion that guides the active material slurry to the slurry discharge portion, and a dam liquid passage portion that guides the dam liquid to the dam liquid discharge portion, 3. The electrode coating die according to claim 2, wherein the pair of support portions includes a first support portion disposed upstream in a coating direction of the active material slurry, and a second support portion disposed downstream in the coating direction.

4. The electrode coating die according to claim 1 , wherein an opening area of ​​the slurry discharge portion is larger than an opening area of ​​the dam liquid discharge portion.

5. 2. The electrode coating die according to claim 1, wherein the length of the slurry discharge portion perpendicular to the coating direction of the active material slurry is wider than the length of the dam liquid discharge portion.

6. a partition wall portion provided between the slurry discharge portion and the dam liquid discharge portion, The electrode coating die according to claim 1 , wherein the partition wall portion is provided so as to form the dam layer that covers at least a part of the inclined surface portion provided at the edge portion of the active material slurry layer.

7. 7. The electrode coating die according to claim 6, wherein the width of the partition wall in a direction perpendicular to the coating direction of the active material slurry is 3% or less of the sum of the long width of the slurry discharge portion and the long width of the dam liquid discharge portion.

8. 4. The electrode coating die according to claim 3, wherein the inclination angle (θ) of the dam liquid passage portion with respect to the longitudinal direction of the dam liquid discharge portion is 90° or less.

9. 2. The electrode coating die according to claim 1, wherein the dam liquid discharge portion is located on a straight line with the position of the slurry discharge portion, or is located offset downstream in the coating direction of the active material slurry.

10. 4. The electrode coating die according to claim 3, wherein the dam liquid discharge section includes the first dam liquid discharge section connected from the dam liquid passage section between two adjacent slurry discharge sections and divided into two discharge sections, and the second dam liquid discharge section connected from the dam liquid passage section at the outermost side of the plurality of slurry discharge sections and consisting of one discharge section.

11. A transfer unit for continuously transferring the current collector of the electrode; and 11. The electrode coating die according to claim 1, wherein an active material layer is applied to the current collector. An electrode coating apparatus comprising:

12. preparing an active material slurry containing an active material, a conductive material, and a solvent; and A method for manufacturing an electrode, comprising a coating step of applying the active material slurry onto a current collector, The method for manufacturing an electrode includes using the electrode coating die according to any one of claims 1 to 10 to simultaneously discharge the active material slurry and a dam liquid onto the current collector so as to form a dam layer that covers at least a portion of an inclined surface portion provided on at least one edge portion of the active material slurry layer coated on the current collector, thereby forming an active material layer.

13. The method of claim 12 , further comprising a drying step of drying the active material layer after the coating step.

14. The method for manufacturing an electrode according to claim 12 , further comprising a slitting step of cutting the electrode manufactured by the method for manufacturing an electrode in a coating direction of the active material slurry.

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