Electrode assembly, cylindrical battery cell, and battery pack including the same

Abstract

According to one embodiment of the present invention, the uncoated portions protruding from the upper and lower portions of the electrode assembly are used as electrode tabs, thereby reducing the internal resistance of the battery cell and increasing the energy density. Furthermore, according to one embodiment of the present invention, the uncoated portion structure of the electrode assembly is improved so that the uncoated portions of the electrode plate do not interfere with the separator during the process of forming the beading portion of the battery can, thereby reducing melting and damage to the separator when the uncoated portions are bent and welded.

Description

[Technical Field]

[0001] This application claims priority to Korean Patent Application No. 10-2022-0183529, filed on December 23, 2022. The present invention relates to an electrode assembly, a cylindrical battery cell, a battery pack including the same, and a vehicle. [Background technology]

[0002] Secondary batteries, which have high applicability to each product group and electrical properties such as high energy density, are commonly used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs), which are powered by electrical sources.

[0003] Such secondary batteries are attracting attention as a new energy source that not only has the primary advantage of dramatically reducing the use of fossil fuels, but also is environmentally friendly because they do not produce any by-products from energy use and can improve energy efficiency.

[0004] Currently, secondary batteries such as lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries are widely used. The operating voltage of such unit secondary battery cells, i.e., unit battery cells, is approximately 2.5 V to 4.5 V. Therefore, when a higher output voltage is required, a battery pack is constructed by connecting multiple battery cells in series. Alternatively, a battery pack may be constructed by connecting multiple battery cells in parallel according to the required charge / discharge capacity of the battery pack. Therefore, the number of battery cells included in the battery pack and the electrical connection configuration can be variously set depending on at least one of the required output voltage and charge / discharge capacity.

[0005] Meanwhile, known types of secondary battery cells include cylindrical, prismatic, and pouch-type battery cells. For example, in the case of a cylindrical battery cell, a separator, which is an insulator, is interposed between a positive electrode and a negative electrode, and the separator is wound up to form a jelly-roll-type electrode assembly, which is then inserted into a battery can to form a battery. Strip-shaped electrode tabs are connected to the uncoated portions of the positive and negative electrodes, respectively, and the electrode tabs electrically connect the electrode assembly to the electrode terminals exposed to the outside. For reference, the positive electrode terminal is the cap plate of the sealing body that seals the opening of the battery can, and the negative electrode terminal is the battery can. Conventional cylindrical battery cells with this structure suffer from problems such as high resistance, large heat generation, and poor current collection efficiency due to current concentration at the strip-shaped electrode tabs connected to the positive electrode uncoated portion and / or negative electrode uncoated portion.

[0006] Resistance and heat generation are not major issues in small cylindrical battery cells with form factors such as 18650 and 21700. However, when the form factor of cylindrical battery cells is increased to be used in electric vehicles, a large amount of heat is generated around the electrode tabs during the fast charging process, which can cause the cylindrical battery cell to catch fire.

[0007] To solve these problems, a cylindrical battery cell (so-called tab-less cylindrical battery cell) has been proposed, which has a structure in which positive and negative electrode uncoated areas are designed to be located at the upper and lower ends of a jelly-roll type electrode assembly, respectively, and current collecting plates are welded to these uncoated areas to improve current collection efficiency.

[0008] Figures 1 to 3 show the manufacturing process of a tabless cylindrical battery cell. Figure 1 shows the structure of the electrode plate, Figure 2 shows the electrode plate winding process, and Figure 3 shows the process of welding a current collector plate to the bent surface of the uncoated portion.

[0009] Referring to Figures 1 to 3, the first electrode plate 10 and the second electrode plate 11 have a structure in which an active material 21 is coated on a sheet-shaped current collector 20, and include an uncoated portion 22 on one long side along the longitudinal direction (X-axis direction).

[0010] The electrode assembly A is fabricated by sequentially stacking a first electrode plate 10 and a second electrode plate 11 together with two separators 12 as shown in Fig. 2, and then winding the stack in the longitudinal direction (X-axis direction). At this time, the uncoated portion of the first electrode plate 10 and the uncoated portion of the second electrode plate 11 are arranged in opposite directions.

[0011] After the winding process, the uncoated portion 10a of the first electrode plate 10 and the uncoated portion 11a of the second electrode plate 11 are bent toward the core side, and then the current collector plates 30 and 31 are welded to the uncoated portions 10a and 11a, respectively.

[0012] No separate electrode tabs are attached to the positive electrode uncoated region 10a and the negative electrode uncoated region 11a, and current collector plates 30 and 31 are connected to external electrode terminals, so that a current path with a large cross-sectional area is formed along the winding axis direction Y' (see arrow) of electrode assembly A, which has the advantage of reducing the resistance of the battery cell. This is because resistance is inversely proportional to the cross-sectional area of ​​the path through which current flows.

[0013] In a tabless cylindrical battery cell, in order to improve the welding characteristics between the uncoated portions 10a, 11a and the current collecting plates 30, 31, it is necessary to apply strong pressure to the welding points of the uncoated portions 10a, 11a to bend the uncoated portions 10a, 11a as flat as possible.

[0014] However, when the welding points of the uncoated portions 10a, 11a are bent, the uncoated portions 10a, 11a may be deformed into irregular shapes. This may result in contact with the electrode plate of the opposite polarity, causing an internal short circuit, or may induce microcracks in the uncoated portions 10a, 11a. Furthermore, as the uncoated portion 32 adjacent to the core of the electrode assembly A is bent, it may block all or a significant portion of the cavity 33 in the core of the electrode assembly A. This may cause problems during the electrolyte injection process. The cavity 33 in the core of the electrode assembly A serves as a passage for injecting electrolyte, and blocking this passage makes it difficult to inject the electrolyte. Furthermore, when an electrolyte injector is inserted into the cavity 33, it may interfere with the uncoated portion 32 near the core, causing the uncoated portion 32 to break.

[0015] In addition, the folded portions of the plain portions 10a and 11a where the current collector plates 30 and 31 are welded must be overlapped in multiple layers without any open spaces (gaps). This ensures sufficient welding strength and prevents the laser from penetrating into the electrode assembly A and melting the separator or active material, even when using cutting-edge technology such as laser welding.

[0016] Meanwhile, in a conventional table-less cylindrical battery cell, a positive electrode uncoated region 10a is formed entirely on the top of the electrode assembly A. Therefore, when the outer periphery of the upper end of the battery can is pressed inward to form a beading portion, the upper peripheral region 34 of the electrode assembly A is compressed by the battery can. This compression causes partial deformation of the electrode assembly A, which can cause the separator 12 to break and an internal short circuit. An internal short circuit in the battery can potentially lead to overheating or explosion of the battery.

[0017] In addition, in the case of non-notched jelly rolls, after assembly, the foil current collector is folded, forming a closed structure inside and outside, which interferes with the movement of electrolyte to the electrodes inside the jelly roll during injection, resulting in uneven electrolyte impregnation characteristics. This is thought to be due to the occurrence of uneven electrolyte impregnation paths during electrolyte impregnation. This leads to a decrease in impregnation uniformity, increasing variation between batteries and forming an unstable solid electrolyte interface (SEI) layer, which increases resistance dispersion.

[0018] Furthermore, in a typical electrode assembly, the area of ​​the positive electrode is smaller than that of the negative electrode (especially the area of ​​the electrode active material portion), and the separator completely covers the electrode active material portion of the first electrode plate and the electrode active material portion of the second electrode plate, particularly in the width direction. In such a case, when the uncoated portions of each electrode plate are folded to flatten the bottom end of the electrode assembly, the folded uncoated portions come into contact with one end of the separator, and the separator may melt and be damaged by the heat applied when welding the uncoated portions. Summary of the Invention [Problem to be solved by the invention]

[0019] The present invention has been made in light of the background of the prior art described above, and an object of the present invention is to provide an electrode assembly having improved electrolyte impregnation characteristics.

[0020] Another object of the present invention is to provide an electrode assembly having an improved uncoated portion structure that can reduce stress applied to the uncoated portions exposed at both ends of the electrode assembly when the uncoated portions are bent.

[0021] Another object of the present invention is to provide an electrode assembly in which the electrolyte injection passage is not blocked even when the non-coating portion is bent.

[0022] Another object of the present invention is to provide an electrode assembly including a structure that can prevent the upper edge of the electrode assembly from coming into contact with the inner surface of the battery can when the upper end of the battery can is pushed in.

[0023] Another object of the present invention is to provide an electrode assembly having improved energy density and reduced resistance.

[0024] Yet another problem to be solved by the present invention is to provide a cylindrical battery cell including an electrode assembly with an improved structure, a battery pack including the same, and a vehicle including the battery pack.

[0025] The problems to be solved by the present invention are not limited to those mentioned above, and 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]

[0026] The present invention relates to an electrode assembly for an electrochemical device. A first embodiment of the present invention relates to the electrode assembly, which includes a first electrode plate, a second electrode plate, and a separator interposed between the first and second electrode plates, and the first electrode plate is a positive electrode plate and the second electrode plate is a negative electrode plate, or the first electrode plate is a negative electrode plate and the second electrode plate is a positive electrode plate, the first electrode plate, the second electrode plate, and the separation membrane are each independently strip-shaped with an aspect ratio of more than 1, and the first electrode plate, the second electrode plate, and the separation membrane are stacked with their longitudinal directions parallel to each other; The first electrode plate, the second electrode plate, and the separator each independently have a first side portion that is a first end in a width direction, and a second side portion that is a second end at a position opposite to the first side portion, the first electrode plate and the second electrode plate include a first portion and a second portion on at least one side, the first portion being an electrode active material portion coated with an electrode active material and extending from the second side portion to the first side portion, and the second portion being a plain portion not coated with an electrode active material and extending from the first side portion to the second side portion to the electrode active material portion; In the electrode assembly, a first side portion of the first electrode plate and a first side portion of the second electrode plate are arranged to face in opposite directions, In the electrode assembly, a first side of the separator protrudes outward from the second side of the first electrode plate and is disposed on the electrode active material portion of the second electrode plate, and the second side of the separator protrudes outward from the second side of the second electrode plate and is disposed on the uncoated portion of the first electrode plate. In a specific embodiment of the present invention, the second electrode plate is a negative electrode plate, and the first electrode plate is a positive electrode plate.

[0027] According to the second embodiment of the present invention, in the first embodiment, the width of the electrode active material portion of the first electrode plate is narrower than the width of the electrode active material portion of the second electrode plate, based on the width direction, and both ends of the electrode active material portion of the first electrode plate in the width direction are arranged between both ends of the electrode active material portion of the second electrode plate in the width direction.

[0028] According to the third embodiment of the present invention, in the first or second embodiment, at least one of the first and second electrode plates has at least a portion of the uncoated area divided into a plurality of segments by incision grooves of a predetermined depth.

[0029] According to a fourth embodiment of the present invention, in the third embodiment, each of the plurality of segments has a rectangular, trapezoidal, triangular, parallelogram, semicircular or semielliptical structure.

[0030] According to the fifth embodiment of the present invention, in the fourth embodiment, the first electrode plate has a segment of the first electrode plate, and the separation membrane is arranged to cover the notched valley of the cut groove of the segment.

[0031] According to the sixth embodiment of the present invention, in any one of the first to fifth embodiments, the electrode assembly has a plurality of winding turns in which the first electrode plate, the second electrode plate, and the separation membrane are wound longitudinally around an axis.

[0032] According to a seventh embodiment of the present invention, in the fifth embodiment, the electrode assembly has a plurality of winding turns in which the first electrode plate, the second electrode plate, and the separator are wound in a longitudinal direction around an axis, All or at least some of the plurality of segments are bent in the radial direction relative to the axis at a bending point that is a point within the segment.

[0033] According to an eighth embodiment of the present invention, in the seventh embodiment, the second side of the separator is disposed on the uncoated portion of the first electrode plate and between the electrode active material portion and the bending point.

[0034] According to a ninth embodiment of the present invention, in the eighth embodiment, the bending point and the second side of the separator are spaced apart by 0.1 mm or more.

[0035] According to a tenth embodiment of the present invention, in any one of the first to ninth embodiments, the uncoated portion of at least one of the first and second electrode plates includes a core-side uncoated portion adjacent to a core of the electrode assembly, an outer periphery-side uncoated portion adjacent to an outer periphery surface of the electrode assembly, and an intermediate uncoated portion interposed between the core-side uncoated portion and the outer periphery-side uncoated portion, At least one of the core-side uncoated portion and the outer-periphery-side uncoated portion has a distance from the electrode active material portion to the first side portion that is relatively shorter than that of the intermediate uncoated portion; The electrode active material portion has a constant width from the core side to the outer periphery side, with the width direction as the reference.

[0036] According to an eleventh embodiment of the present invention, in any one of the first to tenth embodiments, the uncoated portion of at least one of the first and second electrode plates includes a core-side uncoated portion adjacent to a core of the electrode assembly, an outer periphery-side uncoated portion adjacent to an outer periphery surface of the electrode assembly, and an intermediate uncoated portion interposed between the core-side uncoated portion and the outer periphery-side uncoated portion, The core-side uncoated portion has a relatively shorter distance from the electrode active material portion to the first side portion than the intermediate uncoated portion and the outer-side uncoated portion, and the electrode active material portion has a constant width from the core side to the outer side based on the width direction.

[0037] According to the twelfth embodiment of the present invention, in the tenth or eleventh embodiment, the core-side uncoated portion includes an uncoated portion of the electrode plate portion corresponding to the innermost winding turn of the electrode assembly, and the outer-periphery-side uncoated portion includes an uncoated portion of the electrode plate portion corresponding to the outermost winding turn of the electrode assembly.

[0038] According to a thirteenth embodiment of the present invention, in the eleventh or twelfth embodiment, all or at least a part of the intermediate plain portion is divided into a plurality of segments.

[0039] According to a fourteenth embodiment of the present invention, in the tenth or eleventh embodiment, the height of at least a portion of the intermediate uncoated portion increases stepwise from the core side to the outer periphery side in the direction of the winding axis.

[0040] According to a fifteenth embodiment of the present invention, in the thirteenth or fourteenth embodiment, the height of at least a portion of the intermediate uncoated portion increases stepwise from the core side to the outer periphery side in the axial winding direction.

[0041] According to a 16th embodiment of the present invention, in any one of the 3rd to 15th embodiments, the notched valley of each of the segment pieces and the electrode active material portion are spaced apart by a predetermined interval.

[0042] According to the 17th embodiment of the present invention, in any one of the 1st to 16th embodiments, the separation membrane includes a porous polymer substrate and a porous coating layer located on at least one surface of the porous polymer substrate and including inorganic particles and a binder polymer.

[0043] According to the 18th embodiment of the present invention, in the 17th embodiment, the inorganic particles include inorganic particles whose surfaces have hydrophilic properties.

[0044] A 19th embodiment of the present invention relates to a cylindrical battery cell, the cylindrical battery cell including: an electrode assembly according to any one of the first to 18th embodiments; a battery can in which the electrode assembly is housed, the battery can being electrically connected to one of the first electrode plate and the second electrode plate and having a first polarity; a sealing body sealing an open end of the battery can; and a terminal being electrically connected to the other of the first electrode plate and the second electrode plate, having a surface exposed to the outside, and having a second polarity.

[0045] A twentieth embodiment of the present invention relates to a battery pack, the battery pack including the cylindrical battery cell according to the nineteenth embodiment. [Effects of the Invention]

[0046] According to one embodiment of the present invention, the uncoated portions protruding from the upper and lower portions of the electrode assembly are used as electrode tabs, thereby reducing the internal resistance of the battery cell and increasing the energy density.

[0047] According to another embodiment of the present invention, the structure of the uncoated portion of the electrode assembly is improved so that the uncoated portion of the electrode plate does not interfere with the separator during the process of forming the beading portion of the battery can, thereby reducing melting and damage to the separator when the uncoated portion is bent and welded.

[0048] According to another embodiment of the present invention, the structure of the uncoated portion of the electrode assembly is improved to prevent the uncoated portion from tearing when being bent, and the number of overlapping layers of the uncoated portion is increased to improve welding strength. Furthermore, when forming a notch groove in the uncoated portion of the electrode plate, the notch valley can be made as deep as possible (i.e., the distance between the notch valley and the electrode active material portion can be minimized), thereby ensuring a deeper valley during notching.

[0049] According to yet another embodiment of the present invention, the structure of the uncoated portion adjacent to the core of the electrode assembly is improved to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent, thereby facilitating the electrolyte injection process and the welding process of the battery can and the current collector plate.

[0050] According to yet another embodiment of the present invention, it is possible to provide a cylindrical battery cell having a structure in which internal resistance is low, internal short circuits are prevented, and welding strength between a current collector plate and an uncoated portion is improved, as well as a battery pack and a vehicle including the same.

[0051] The present invention also provides various other effects, which will be described later with reference to the embodiments, but explanations of effects that can be easily inferred by ordinary skilled artisans will be omitted.

[0052] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited to the matters described in the drawings. [Brief explanation of the drawings]

[0053] [Figure 1] 1 is a plan view showing the structure of an electrode plate used in manufacturing a conventional tabless cylindrical battery cell. [Figure 2] 1A and 1B are diagrams illustrating a winding process of an electrode plate of a conventional tabless cylindrical battery cell. [Figure 3]10A and 10B are views showing a process of welding a current collector plate to a bent surface of a non-coating portion in a conventional tabless cylindrical battery cell. [Figure 4] FIG. 1 is a plan view showing the structure of an electrode plate according to a first embodiment of the present invention. [Figure 5] FIG. 6 is a plan view showing the structure of an electrode plate according to a second embodiment of the present invention. [Figure 6] FIG. 10 is a plan view showing the structure of an electrode plate according to a third embodiment of the present invention. [Figure 7a] FIG. 10 is a plan view showing the structure of an electrode plate according to a fourth embodiment of the present invention. [Figure 7b] FIG. 10 is a plan view showing the structure of an electrode plate according to a fifth embodiment of the present invention. [Figure 7c] FIG. 10 is an enlarged view showing the cut-out portion in more detail. [Figure 8] 1 is a cross-sectional view of an electrode assembly having a conventional laminated structure; [Figure 9a] 1 is a cross-sectional view of an electrode assembly showing a stacked structure according to the present invention; [Figure 9b] 1 is a cross-sectional view of an electrode assembly showing a stacked structure according to the present invention; [Figure 10a] 10 is a diagram illustrating definitions of width, height, and spacing pitch of segments according to an embodiment of the present invention. [Figure 10b] 10 is a diagram illustrating definitions of width, height, and spacing pitch of segments according to an embodiment of the present invention. [Figure 11] FIG. 1 is a cross-sectional view of a jelly-roll type electrode assembly in which the electrode plates of the first embodiment are applied to a first electrode plate (positive electrode plate) and a second electrode plate (negative electrode plate), taken along the Y-axis direction (winding axis direction). [Figure 12] FIG. 10 is a cross-sectional view of a jelly-roll type electrode assembly in which the electrode plates of the second embodiment are applied to the first electrode plate (positive electrode plate) and the second electrode plate (negative electrode plate), taken along the Y-axis direction (winding axis direction). [Figure 13]FIG. 10 is a cross-sectional view of a jelly-roll type electrode assembly in which any one of the electrode plates of the third to fifth embodiments (modifications thereof) is used as the first electrode plate (positive electrode plate) and the second electrode plate (negative electrode plate) taken along the Y-axis direction (winding axis direction). [Figure 14] 10 is a cross-sectional view of an electrode assembly according to another embodiment of the present invention taken along the Y-axis direction (winding axis direction). [Figure 15] 10 is a cross-sectional view of an electrode assembly according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction). [Figure 16] 10 is a cross-sectional view of an electrode assembly according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction). [Figure 17] 2 is a cross-sectional view of a cylindrical battery cell according to an embodiment of the present invention taken along a Y-axis direction. FIG. [Figure 18] FIG. 4 is a cross-sectional view of a cylindrical battery cell according to another embodiment of the present invention taken along the Y-axis direction. [Figure 19] FIG. 10 is a cross-sectional view of a cylindrical battery cell according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 20] FIG. 10 is a cross-sectional view of a cylindrical battery cell according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 21] FIG. 10 is a cross-sectional view of a cylindrical battery cell according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 22] FIG. 10 is a cross-sectional view of a cylindrical battery cell according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 23] FIG. 10 is a cross-sectional view of a cylindrical battery cell according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 24] FIG. 10 is a cross-sectional view of a cylindrical battery cell according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 25] FIG. 10 is a cross-sectional view of a cylindrical battery cell according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 26]1 is a diagram illustrating a schematic configuration of a battery pack according to an embodiment of the present invention; [Figure 27] 1 is a schematic diagram of a vehicle including a battery pack according to an embodiment of the present invention; [Figure 28] FIG. 10 is a graph confirming the capacity retention rate characteristics of batteries according to an example and a comparative example. [Figure 29] 3A and 3B are photographic images showing the electrode assembly according to the present invention before and after winding. [Figure 30] FIG. 2 is a diagram showing the positions where impregnated samples were collected in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0054] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and phrases used in the specification and claims should not be construed as being limited to their ordinary and dictionary meanings, but should be construed as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventors themselves can appropriately define the concepts of terms in order to best describe the invention.

[0055] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can be substituted therefor at the time of this application.

[0056] In addition, to facilitate understanding of the invention, the accompanying drawings may not be drawn to scale, and the dimensions of some components may be exaggerated. In addition, the same reference numerals may be used to refer to the same components in different embodiments.

[0057] (definition) For ease of explanation, in this specification, a sheet-like structure such as a first electrode plate, a second electrode plate, and a separator, or an electrode assembly in which these are stacked, is strip-shaped with an aspect ratio exceeding 1. Herein, the direction based on the longer of the horizontal and vertical sides is referred to as the longitudinal direction (X-axis), and the direction perpendicular to the longitudinal direction, i.e., the direction based on the relatively shorter side, is referred to as the width direction (Y-axis). Furthermore, since the electrode assembly is wound up in a jelly roll shape, the direction along the longitudinal direction of the winding shaft of the electrode assembly is referred to as the axial direction (Y'-axis). The axial direction may be the same as the width direction. Furthermore, the direction surrounding the winding shaft is referred to as the circumferential direction or circumferential direction (X'-axis). The circumferential direction or circumferential direction may be the same as the longitudinal direction. Furthermore, the direction toward or away from the winding shaft is referred to as the radial direction or radial direction (Z-axis). Of these, the direction approaching the winding shaft is called the centripetal direction, and the direction away from the winding shaft is called the centrifugal direction.

[0058] First, the structure of an electrode assembly according to an embodiment of the present invention will be described.

[0059] The electrode assembly includes a first electrode plate, a second electrode plate, and a separator interposed between the first and second electrode plates. In one embodiment of the present invention, the first electrode plate, the second electrode plate, and the separator are each independently strip-shaped with an aspect ratio of greater than 1. In the electrode assembly, the first electrode plate, the second electrode plate, and the separator may be stacked with their respective longitudinal directions parallel to each other.

[0060] The first and second electrode plates include an electrically conductive foil as a current collector and an electrode active material portion formed to a predetermined thickness on a second portion on at least one surface of the foil. In one embodiment of the present invention, the first electrode plate may be a positive electrode plate, and the second electrode plate may be a negative electrode plate. Conversely, the first electrode plate may be a negative electrode plate, and the second electrode plate may be a positive electrode plate. In a specific embodiment of the present invention, the first electrode plate may be a positive electrode plate, and the second electrode plate may be a negative electrode plate.

[0061] The first electrode plate, the second electrode plate, and the separator each independently have a first side portion at one end in the width direction and a second side portion at the other end opposite the first side portion. The ends of the first and second electrode plates in the width direction correspond to the first and second sides, and the first side portion is included in the uncoated portion of each electrode plate, and the second side portion is included in the electrode active material portion of each electrode plate. The first side portion and the second side portion are disposed on opposite sides in the width direction (Y-axis direction).

[0062] Each electrode plate includes a first portion and a second portion on at least one side. The first portion is an electrode active material portion coated with an electrode active material and extends from the second side toward the first side. In one embodiment of the present invention, the electrode active material portion of each electrode plate may maintain a constant width along the longitudinal direction (X-axis direction). The second portion is an uncoated portion not coated with an electrode active material and extends from the first side toward the second side to the electrode active material portion. As will be described later, the uncoated portion of each electrode plate may not have a constant width along the longitudinal direction. That is, the distance from the boundary between the electrode active material portion and the uncoated portion to the first side may not be constant. The electrode plates may each have the electrode active material portion formed independently on both sides. When electrode active material portions are formed on both sides, the electrode active material portion on one side and the electrode active material portion on the back side are formed in opposing positions. That is, in each electrode plate, the uncoated portion is a portion on both sides of the current collector where no electrode active material portion is formed. The uncoated portion may be used as an electrode tab as it is, or may be cut open to form segments as described below, and the segments may be used as electrode tabs.

[0063] Meanwhile, in the electrode assembly, the first side of the first electrode plate and the first side of the second electrode plate are arranged to face in opposite directions (see FIGS. 9a and 9b).

[0064] In addition, in the electrode assembly, the width of the electrode active material portion of the first electrode plate is narrower than the width of the electrode active material portion of the second electrode plate, and both ends of the electrode active material portion of the first electrode plate in the width direction are disposed between both ends of the electrode active material portion of the second electrode plate in the width direction (see FIGS. 9a and 9b).

[0065] In the electrode assembly, a first side of the separator protrudes outward from a second side of the first electrode plate and is disposed on the electrode active material portion of the second electrode plate, and a second side of the separator protrudes outward from the second side of the second electrode plate and is disposed on the uncoated portion of the first electrode plate (see FIGS. 9a and 9b).

[0066] In a specific embodiment of the present invention, the second electrode plate is preferably a negative electrode plate. When designing a battery, considering the N / A ratio, the positive electrode has a large capacity. To accommodate this positive electrode capacity, the negative electrode is designed to have a larger dimension (width) than the positive electrode. As a result, even though the positive and negative electrodes do not directly face each other, the surface of the electrode active material portion of the positive electrode plate is entirely covered with a separator, while the surface of the electrode active material portion of the negative electrode plate is partially exposed. This partially exposes the negative electrode active material portion of the negative electrode plate, thereby improving the impregnation of the electrode assembly. Furthermore, the width of the electrode active material portion of the positive electrode plate is narrower than the width of the electrode active material portion of the negative electrode plate, and the positive electrode active material portion may be positioned so that it does not exceed the negative electrode active material portion based on the width.

[0067] Meanwhile, in one embodiment of the present invention, at least a portion of the uncoated region of at least one of the first and second electrode plates is divided into a plurality of segments by incisions of a predetermined depth. For example, the positive electrode uncoated region may have a plurality of segments over the entire region or at least a portion of the first side. Additionally or independently, the negative electrode uncoated region may have a plurality of segments over the entire region or at least a portion of the first side. Each of the plurality of segments may have a rectangular, trapezoidal, triangular, parallelogram, semicircular, or semi-elliptical shape.

[0068] 4 is a plan view showing the structure of an electrode plate 40 according to a first embodiment of the present invention. The electrode plate can be applied to a first electrode plate, a second electrode plate, or both the first and second electrode plates.

[0069] Referring to Figure 4, the second side is a side formed along the bottom end of the electrode active material part 42 in the winding axis (Y axis) direction, and the first side is a side formed along the top end of the plain part 43 in the winding axis (Y axis) direction.

[0070] The electrode plates each independently include a first portion, which is an electrode active material portion, on at least one or both sides. The first portion extends a predetermined length from the second side toward the first side. Figure 4 is a diagram showing the shape of the electrode plate before the electrode assembly is wound up. Referring to this, the electrode active material portion may have a constant width along the entire length of the electrode plate in the axial direction, from the second side to the beginning of the uncoated portion.

[0071] 4, an electrode plate according to one embodiment of the present invention may be a second electrode plate, a first electrode plate, or both the second and first electrode plates. The electrode plate 40 includes a current collector 41 made of metal foil and an electrode active material portion 42. The metal foil may be aluminum or copper, and is appropriately selected depending on the polarity of the electrode plate 40. The electrode active material portion is formed on at least one surface of the current collector 41, and an uncoated portion 43 is disposed on the long edge of the current collector in the longitudinal direction (X-axis direction). The uncoated portion 43 is an area that is not coated with the electrode active material.

[0072] In one embodiment of the present invention, an insulating coating layer 44 may be formed at the boundary between the electrode active material portion 42 and the uncoated portion 43. The insulating coating layer 44 is formed so that at least a portion thereof overlaps the boundary between the electrode active material portion 42 and the uncoated portion 43. The insulating coating layer 44 may include a polymer resin and / or an inorganic material such as Al2O3.

[0073] In one embodiment of the present invention, the uncoated portion 43 may be divided into a core-side uncoated portion B1 adjacent to the core side of the electrode assembly, an outer-periphery-side uncoated portion B3 adjacent to the outer periphery of the electrode assembly, and an intermediate uncoated portion B2 interposed between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0074] When each electrode plate 40 is wound into a jelly-roll-type electrode assembly, the core-side uncoated region B1, the outer periphery-side uncoated region B3, and the intermediate uncoated region B2 may be defined as the uncoated region adjacent to the core side, the uncoated region adjacent to the outer periphery, and the uncoated region excluding these, respectively. The boundary between the core-side uncoated region B1 and the intermediate uncoated region B2 may be appropriately defined as a point where the height (or variation pattern) of the uncoated region substantially changes from the core side to the outer periphery of the electrode assembly, or as a predetermined percentage point based on the radius of the electrode assembly (e.g., 5%, 10%, 15% of the radius). The boundary between the intermediate uncoated region B2 and the outer periphery-side uncoated region B3 may be defined as a point where the height (or variation pattern) of the uncoated region substantially changes from the outer periphery to the core side of the electrode assembly, or as a predetermined percentage point based on the radius of the electrode assembly (e.g., 85%, 90%, 95% of the radius). Once the boundaries between the core-side uncoated area B1 and the intermediate uncoated area B2 and the boundary between the intermediate uncoated area B2 and the outer-side uncoated area B3 are identified, the intermediate uncoated area B2 can be automatically identified. If only the boundary between the core-side uncoated area B1 and the intermediate uncoated area B2 is identified, the boundary between the intermediate uncoated area B2 and the outer-side uncoated area B3 can be appropriately selected as a point near the outer periphery of the electrode assembly. Conversely, if only the boundary between the intermediate uncoated area B2 and the outer-side uncoated area B3 is identified, the boundary between the core-side uncoated area B1 and the intermediate uncoated area B2 can be appropriately selected as a point near the core side of the electrode assembly. In the first embodiment, the height of the uncoated area 43 is not constant but varies relatively in the winding direction X'. That is, the height (length in the Y-axis direction) of the outer-side uncoated area B3 is relatively lower than the core-side uncoated area B1 and the intermediate uncoated area B2. In one embodiment of the present invention, at least a portion of the uncoated portion of the electrode plate according to the first embodiment may be divided into a plurality of sections by incisions of a predetermined depth (not shown).

[0075] FIG. 5 is a plan view showing the structure of an electrode plate 45 according to a second embodiment of the present invention.

[0076] 5, the electrode plate 45 of the second embodiment differs from the first embodiment only in that the height of the outer peripheral uncoated portion B3 gradually decreases toward the outer periphery, but the other configurations are substantially the same. In one modified embodiment, the outer peripheral uncoated portion B3 may have a stepped shape (see dotted lines) in which the height decreases in stages. In one embodiment of the present invention, at least a portion of the uncoated portion of the electrode plate according to the second embodiment may be divided into a plurality of segments by incisions of a predetermined depth (not shown).

[0077] FIG. 6 is a plan view showing the structure of an electrode plate 50 according to a third embodiment of the present invention. Referring to FIG. 6, in the electrode plate 50 of the third embodiment, the heights of the core-side uncoated region B1 and the outer-side uncoated region B3 are relatively smaller than the middle uncoated region B2. The heights of the core-side uncoated region B1 and the outer-side uncoated region B3 may be the same or different. Preferably, the height of the middle uncoated region B2 may have a stepped shape, gradually increasing from the core side to the outer side.

[0078] Patterns 1 to 7 are obtained by dividing the intermediate plain portion B2 around the positions where the height of the plain portion 43 changes. Preferably, the number of patterns, and the height (length in the Y-axis direction) and width (length in the X-axis direction) of each pattern can be adjusted to maximize stress distribution during the folding process of the plain portion 43. The purpose of dispersing stress is to prevent the plain portion 43 from tearing.

[0079] The width d of the core-side uncoated portion B1 B1 is designed so that the cavity in the core of the electrode assembly is not blocked when the pattern of the middle plain portion B2 is bent toward the core.

[0080] At least a portion of the uncoated portion of the electrode plate according to the third embodiment may be divided into a plurality of sections by incision grooves of a predetermined depth (not shown).

[0081] In one example, the width d of the core-side uncoated portion B1B1 can increase in proportion to the height of the plain portion of Pattern 1 or the height of the segment of Pattern 1.

[0082] In a specific example, when the electrode plate 50 is used to manufacture an electrode assembly for a cylindrical cell with a form factor of 46800, the width d of the core-side uncoated portion B1 is B1 can be set to 180 mm to 350 mm depending on the diameter of the core of the electrode assembly.

[0083] In one example, the width of each pattern can be designed to accommodate the same winding turn of the electrode assembly.

[0084] In another example, the height of the middle uncoated portion B2 may have a step shape that increases and then decreases from the core side toward the outer periphery.

[0085] In yet another example, the outer circumferential uncoated portion B3 may be modified to have the same structure as that of the second embodiment.

[0086] In yet another example, the pattern structure applied to the middle solid portion B2 may be extended to the outer solid portion B3 (see dotted lines).

[0087] 7a is a plan view showing the structure of an electrode plate 60 according to a fourth embodiment of the present invention, and FIG. 7b is a plan view showing the structure of an electrode plate 70 according to a fifth embodiment of the present invention. In FIG. 7a and FIG. 7b, it is shown that a divided piece is formed over the entire length of the middle uncoated portion.

[0088] 7a, in the fourth embodiment of the electrode plate 60, the heights of the core-side uncoated portion B1 and the outer-side uncoated portion B3 are relatively lower than the middle uncoated portion B2. The heights of the core-side uncoated portion B1 and the outer-side uncoated portion B3 may be the same or different.

[0089] Preferably, at least a portion of the intermediate uncoated portion B2 may include a plurality of minute segments 61. The height of the plurality of minute segments 61 may increase stepwise from the core side toward the outer periphery side.

[0090] The segment 61 may be laser notched or may be formed by a known metal foil cutting process such as ultrasonic cutting or punching.

[0091] In the fourth embodiment, to prevent damage to the electrode active material portion 42 and / or the insulating coating layer 44 during the bending process of the uncoated portion 43, a gap of a predetermined distance is preferably provided between the notch valley between the divided pieces 61 and the electrode active material portion 42. This is because stress is concentrated near the lower end of the cutting line when the uncoated portion 43 is bent. The gap is preferably 0.2 mm to 4 mm. Adjusting the gap within this range can prevent damage to the electrode active material portion 42 and / or the insulating coating layer 44 near the lower end of the cutting line due to stress generated during the bending process of the uncoated portion 43. In addition, the gap can prevent damage to the electrode active material portion 42 and / or the insulating coating layer 44 due to tolerances during notching or cutting of the divided pieces 61. Preferably, when the electrode plate 40 is wound into an electrode assembly, at least a portion of the insulating coating layer 44 may be exposed to the outside of the separator. In this case, when the segment 61 is bent, the insulating coating layer 44 can support the notched valley.

[0092] The gap between the notched valley of the segment and the electrode active material portion may be preferably 1.0 mm or more, which is more effective when the electrode is a negative electrode.

[0093] The gap between the notched valley of the segment and the electrode active material portion may be more preferably 2.0 mm or more, which is particularly effective when the electrode is a positive electrode.

[0094] A gap smaller than the above range may not be able to fully exert the above-mentioned damage prevention effect, and a cap larger than the above range may result in no further increase in damage prevention effect and only a decrease in the electrode capacitance.

[0095] The boundary between the uncoated region where the electrode active material portion is not coated and the region where the electrode active material portion is coated may be covered with an insulating layer, and in this case, a predetermined gap may also be provided between the notched valley of the divided piece and the insulating layer.

[0096] Such a gap may be between 0.2 mm and 1.5 mm.

[0097] A gap smaller than the above range may not be able to fully exert the above-mentioned damage prevention effect, and a gap larger than the above range may result in a decrease in the effect of supporting the bending of the insulating coating layer without further increasing the damage prevention effect.

[0098] The plurality of segment pieces 61 may be arranged in a plurality of segment groups from the core side toward the outer periphery side. The width, height, and spacing pitch of the segment pieces belonging to the same segment group may be substantially the same.

[0099] FIG. 7b is a plan view showing the structure of an electrode plate 70 according to a fifth embodiment of the present invention.

[0100] Referring to FIG. 7b, the electrode plate 70 of the fifth embodiment is substantially identical in configuration to the fourth embodiment (or modified form), except that the shape of the segment 61' is changed from a square to a trapezoid, compared to the fourth embodiment.

[0101] Next, an electrode assembly according to an embodiment of the present invention will be described in more detail. Figure 8 is a cross-sectional view of an electrode assembly having a conventional laminated structure. Referring to Figure 8, the electrode active material portions of the first and second electrodes are entirely covered with a separator in the width direction, and both ends of the separator protrude outward from the electrode active material portions.

[0102] 9a and 9b are cross-sectional views of an electrode assembly having a stacked structure according to the present invention. Referring to these figures, the first side of the first electrode plate and the first side of the second electrode plate are arranged to face in opposite directions, the width of the electrode active material portion of the first electrode plate is narrower than the width of the electrode active material portion of the second electrode plate, and both ends of the electrode active material portion of the first electrode plate in the width direction are disposed between both ends of the electrode active material portion of the second electrode plate in the width direction. As described above, in one embodiment of the present invention, it is preferable that the second electrode plate is a negative electrode plate and the first electrode plate is a positive electrode plate.

[0103] In the electrode assembly, a first side of the separator protrudes outward from a second side of the first electrode plate and is disposed on an electrode active material portion of the second electrode plate, and a second side of the separator protrudes outward from the second side of the second electrode plate and is disposed on an uncoated portion of the first electrode plate.

[0104] Next, the position of the separator in the electrode assembly of the present invention will be described in more detail with reference to FIGS. 9a and 9b.

[0105] 9a and 9b, a first side portion SP1, which is one end of the separator, protrudes outward from a second side portion of the first electrode plate E1 and is disposed on the electrode active material portion of the second electrode plate E2.

[0106] In one embodiment of the present invention, the distance L1 between the first side of the separator and the boundary (Bou) between the electrode active material portion and the uncoated portion of the second electrode plate may be up to about 3.0 mm. If the distance (Bou) from the first side of the separator to the boundary (Bou) between the electrode active material portion and the uncoated portion of the second electrode plate excessively exceeds the above range, the width of the positive electrode active material portion becomes excessively shorter than that of the negative electrode active material portion, making it difficult to achieve an appropriate NP ratio. Meanwhile, the distance L1 may be 0.3 mm or more, 0.5 mm or more, or 1.0 mm or more. If the distance L1 is not sufficiently secured, the exposed amount of the separator and the electrode active material portion of the second electrode plate (e.g., the negative electrode plate) is reduced, and the effect of improving impregnation during electrolyte injection cannot be fully achieved.

[0107] Meanwhile, the distance L2 between the second side of the first electrode plate and the first side of the separator is preferably at least 1.0 mm. For example, the distance L2 may be 1.2 mm or more, 1.5 mm or more, 2.0 mm or more, or 2.5 mm or more. If the distance is too short, the separator may not sufficiently insulate the positive electrode and the negative electrode. Meanwhile, the distance L2 is not particularly limited, but may be 5.0 mm or less, 4.5 mm or less, 4.0 mm or less, 3.5 mm or less, 3.0 mm or less, 2.5 mm or less, or 2.0 mm or less. If the distance L2 is too large, an appropriate NP ratio cannot be designed, and the width of the positive electrode is too narrow to ensure sufficient battery capacity.

[0108] Meanwhile, in a specific embodiment of the present invention, the ratio of the distance L1 to the distance L2 may be set to 2:1 to 3:1.

[0109] 9a and 9b, the second side SP2 of the separator protrudes outward from the second side of the second electrode plate E2 and is disposed on the uncoated portion of the first electrode plate E1. In a specific embodiment of the present invention, the uncoated portion of the first electrode plate may include a plurality of segments, and the second side of the separator may be disposed to cover the notched valleys of the cut grooves of the segments of the uncoated portion of the first electrode plate. In one embodiment of the present invention, the notched valleys between the plurality of segments may be located at the same position.

[0110] In one embodiment of the present invention, the electrode assembly may be formed in a jelly-roll shape by winding the first electrode plate, the second electrode plate, and the separator in one direction around an axis, and the jelly-roll type electrode assembly may have a plurality of winding turns. In the jelly-roll type electrode assembly, all or at least some of the plurality of segments are bent radially relative to the axis at a bending point that is a point within the segment. In one embodiment of the present invention, the bending point may be a point between a notched valley and an uppermost end of each segment, and the distance between the uppermost end of the segment and the bending point may be shorter than the distance between the uppermost end of the segment and the notched valley.

[0111] More specifically, the second side portion, which is the other end of the separator, may be located between the bending point of the first electrode plate and Bou (the boundary between the electrode active material portion and the uncoated portion), and may be disposed to protrude beyond the second side portion of the second electrode plate.

[0112] The size and shape of the uncoated portions and the segments of each electrode plate will be described in more detail below.

[0113] Meanwhile, in one embodiment of the present invention, the uncoated portions of one or both of the first and second electrode plates may have different heights along the longitudinal direction. Furthermore, the plurality of division segments formed in the uncoated portions may also have different heights along the longitudinal direction, and the shapes of the incision grooves may vary, and the heights of the notch valleys of the incision grooves may also vary. That is, the shapes and sizes of the division segments and the shapes and sizes of the incision grooves may be different from each other.

[0114] In one embodiment of the present invention, the uncoated portion includes a core-side uncoated portion adjacent to the core of the electrode assembly, an outer-periphery-side uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion interposed between the core-side uncoated portion and the outer-periphery-side uncoated portion.

[0115] Preferably, at least one of the core-side uncoated portion and the outer-periphery-side uncoated portion may be relatively lower in height than the intermediate uncoated portion.

[0116] In this specification, the height of the uncoated portion and the height of the division segment refer to the distance from the boundary between the electrode active material portion and the uncoated portion, i.e., the boundary between the electrode active material portion and the uncoated portion, to the first side. More specifically, in a section where no division segment is formed, the height of the uncoated portion refers to the distance from the boundary between the electrode active material portion and the uncoated portion to the first side. In a section where a division segment is formed, the first side refers to the position corresponding to the top of the division segment. The portion that forms the groove between the division segments is not taken into consideration when measuring the height of the uncoated portion in the section where the division segment is formed.

[0117] The height of the notch valley is based on the lowest part of the cut groove.

[0118] In one embodiment of the present invention, the electrode assembly is wound into a jelly roll shape, and all or at least some of the segments are bent in the radial direction (toward the winding center) of the electrode assembly or in the opposite radial direction. The segments may be bent at a bending point, which is a position spaced a predetermined height above the notch valley (bottom of the notch groove). In one embodiment of the present invention, the bending point refers to a point where the inclination of a tangent to a portion of the segment that is actually bent toward the center by an external force begins to become 45° or less. The inclination of a tangent refers to the angle between a tangent to the bending point and a plane perpendicular to the winding axis of the electrode assembly.

[0119] Meanwhile, in one embodiment of the present invention, the heights of the plurality of incision grooves corresponding to the notch valleys may be the same or different from each other.

[0120] Meanwhile, in one embodiment of the present invention, the bending point may be located approximately 2 mm to 3 mm above the notch valley.

[0121] In one embodiment of the present invention, the second side of the separator may be disposed on the uncoated portion of the first electrode plate and may be disposed lower than the height of the bending point of the divided piece of the first electrode plate.

[0122] According to one embodiment of the present invention, the second side of the separator is controlled to be located below the bending point, i.e., near the electrode active material portion, so that the electrolyte flows into the electrode assembly along the notched valley (open space), which is advantageous for impregnation. Specifically, when the electrolyte is injected into the electrode assembly, it moves into the notched groove between the divided segments, and then the electrolyte again impregnates one end of the separator located near the notched valley, and finally impregnates into the electrode active material portion. As a result, the electrolyte impregnation uniformity within the electrode assembly is improved.

[0123] The more one end of the separator in the width direction protrudes toward the outside of the electrode assembly, the more negatively it affects the welding characteristics. Also, the more one end of the separator in the width direction is positioned toward the inside of the jelly roll, i.e., toward the inside of the electrode assembly, the greater the risk of short-circuiting between the positive and negative electrodes, which is problematic.

[0124] Therefore, one embodiment of the present invention is characterized in that both ends of the separator in the width direction are controlled to be positioned at specific positions on the first and second electrode plates, as described above.

[0125] According to a more specific embodiment of the present invention, the electrode assembly is wound into a jelly roll shape, and the "smallest height" of the "folded segments" in the plain portion of each electrode plate is defined as the "minimum folded segment."

[0126] According to a specific embodiment of the present invention, the minimum bending segment of each electrode plate may be 2 mm or more, and in this case, the height of the minimum bending segment is higher than the height of the bending point. If the height of the segment of an electrode plate is less than 2 mm, the segment may not be smoothly bent due to interference between the separator and the segment. Therefore, the minimum bending segment of each electrode plate may be determined from a segment having a height of 2 mm or more.

[0127] In one embodiment of the present invention, each electrode plate may further include a segment (segment A) that is lower in height than the minimum bent segment. In this case, segment A is not bent. In a specific embodiment, segment A may be disposed closer to the core than other segments among the plurality of segments.

[0128] In an embodiment of the present invention, each electrode plate may not include a segment having a height lower than the minimum bent segment, and the minimum bent segment may be the minimum segment.

[0129] In one embodiment of the present invention, the second side of the separator may be positioned at a position less than 50%, within 40%, within 30%, within 20%, or within 10% of the height Ha of the smallest bent segment of the first electrode plate. Preferably, the separator may be positioned on the uncoated portion of the first electrode plate within 30% of the height Ha of the smallest bent segment. In this case, the separator may be positioned so that the notch valley of the incision groove between the segments of the first electrode plate is covered and not exposed. If the second side of the separator is positioned beyond the above range, the separator may be damaged by heat when the segments are welded in a subsequent step.

[0130] 7c, the segment of Group 1 of the first electrode plate may be the smallest bent segment, and the second side of the separator may be located less than 50% or within 30% of the height Ha of the smallest bent segment. More specifically, the segment of Group 1 may be the smallest bent segment, and the second side of the separator may be located on the positive electrode uncoated portion within 30% of the height Ha of the smallest bent segment.

[0131] According to an embodiment of the present invention, the second side of the separator may be located within 3 mm or 1.5 mm from the edge of the first electrode plate.

[0132] FIG. 10a is a diagram showing the definition of the width, height and spacing between the segments 61, i.e., the separation pitch, according to an embodiment of the present invention.

[0133] 10a, the width C1, height C2, and spacing pitch C3 of the divided pieces 61 are designed to prevent tearing of the plain portion 43 during bending and to improve weld strength by sufficiently increasing the number of overlapping layers of the plain portion 43 while preventing abnormal deformation of the plain portion 43. Abnormal deformation refers to the C4 portion being unable to maintain a straight state and collapsing, resulting in irregular deformation.

[0134] According to one embodiment of the present invention, the width C1 of the segment 61 can be adjusted preferably within a range of 1 mm to 6 mm. If C1 is less than 1 mm, when the segment 61 is bent toward the core, the overlap may not be sufficient to ensure sufficient welding strength, or an empty space (gap) may be generated. On the other hand, if C1 exceeds 6 mm, the uncoated portion 43 near the notch valley may be torn by stress when the segment 61 is bent, depending on the curvature of the wound electrode. Furthermore, the height C2 of the segment 61 can be adjusted within a range of 2 mm to 10 mm. If the height C2 of the segment 61 is less than 2 mm, the segment 61 may not be bent smoothly, or when the segment 61 is bent toward the core, the overlap may not be sufficient to ensure sufficient welding strength, or an empty space (gap) may be generated. On the other hand, if C2 exceeds 10 mm, it is difficult to manufacture an electrode plate while maintaining uniform flatness of the uncoated portion in the winding direction X. That is, the uncoated portion becomes higher and swells.

[0135] Furthermore, the spacing pitch C3 of the segment pieces 61 can be adjusted within a range of 0.05 mm to 1 mm or 0.5 mm to 1 mm. If C3 is less than 0.05 mm, stress may be applied when the segment pieces 61 are bent, causing the uncoated portion 43 near the notch valley to break. On the other hand, if the spacing pitch C3 exceeds 1 mm, the segment pieces 61 may not overlap enough to ensure sufficient welding strength when bent, or empty spaces (gaps) may be generated.

[0136] In one embodiment of the present invention, the corners of the two divided pieces may be connected in a straight line, i.e., the bottom portion of the cut groove may be a flat straight line extending in the winding direction X. A rounded reinforcement portion may be added to the corners.

[0137] The radius r of the round reinforcement portion may be 0.02 mm or more. If the radius is greater than this, the stress dispersion effect can be reliably achieved. The radius of the round reinforcement portion may be 0.1 mm or less. If the radius is greater than 0.1 mm, the stress dispersion effect will not be further increased, and the space near the bottom of the cut groove may be reduced, which may hinder the impregnation of the electrolyte.

[0138] Referring further to FIG. 7a, the width d of the core-side uncoated portion B1 B1 is designed so that when the divided piece 61 of the middle plain portion B2 is bent toward the core, the cavity of the core of the electrode assembly is not blocked.

[0139] In one example, the width d of the core-side uncoated portion B1 B1 may increase in proportion to the height C2 of the segment 61 of group 1.

[0140] In a specific example, when the electrode plate 60 is used to manufacture an electrode assembly for a cylindrical cell with a form factor of 46800, the width d of the core-side uncoated portion B1 is B1 can be set to 180 mm to 350 mm depending on the diameter of the core of the electrode assembly.

[0141] In one example, the width of each segment group can be designed to form the same winding turn of the electrode assembly.

[0142] In another example, the width and / or height and / or spacing pitch of the minute segments 61 belonging to the same minute segment group may increase or decrease gradually and / or stepwise and / or irregularly within the group.

[0143] Groups 1 to 7 are merely examples of segment groups. The number of groups and the number of segment pieces 61 included in each group can be adjusted so that the segment pieces 61 are stacked in multiple layers to maximize stress distribution during the bending process of the plain portion 43 and ensure sufficient welding strength.

[0144] In yet another example, the height of the outer plain portion B3 may decrease gradually or in steps, as in the first and second embodiments. The divided structure of the intermediate plain portion B2 may extend to the outer plain portion B3 (see dotted lines). In this case, the outer plain portion B3 may also include multiple divided segments, similar to the intermediate plain portion B2. In this case, the divided segments of the outer plain portion B3 may have a greater width, height, and / or spacing pitch than the intermediate plain portion B2.

[0145] In a specific example, when the electrode plate 60 is used to manufacture an electrode assembly for a cylindrical cell with a form factor of 46800, the segments may be formed in eight groups. In this case, the segments of groups 1 to 7 may be formed in the middle uncoated portion B2, and the segment of group 8 may be formed in the outer uncoated portion B3 as in the example described above.

[0146] In a specific example, the width d of the core-side uncoated portion B1 B1 The width of Group 1 may be 35% to 40% of the width of core-side plain portion B1. The width of Group 2 may be 130% to 150% of the width of Group 1. The width of Group 3 may be 120% to 135% of the width of Group 2. The width of Group 4 may be 85% to 90% of the width of Group 3. The width of Group 5 may be 120% to 130% of the width of Group 4. The width of Group 6 may be 100% to 120% of the width of Group 5. The width of Group 7 may be 90% to 120% of the width of Group 6. The width of Group 8 may be 115% to 130% of the width of Group 7.

[0147] The reason why the widths of groups 1 to 8 do not show a consistent increase or decrease pattern is that although the width of the segments gradually increases from group 1 to group 8, the number of segments included in a group is limited to an integer. Therefore, the number of segments may decrease in a particular segment group. Therefore, the width of the group may show an irregular change from the core side to the outer periphery side, as shown in the example above.

[0148] That is, when the winding direction widths of three adjacent segment groups in the radial direction of the electrode assembly are W1, W2, and W3, respectively, the electrode assembly may include a combination of segment groups in which W3 / W2 is smaller than W2 / W1.

[0149] In the specific example described above, this applies to groups 4 to 6. The width ratio of group 5 to group 4 is 120% to 130%, and the width ratio of group 6 to group 5 is 100% to 120%, which is smaller than 120% to 130%.

[0150] FIG. 10b is a diagram showing the definition of the width, height and separation pitch of the trapezoidal segment 61'.

[0151] Referring to FIG. 10b, the width D1, height D2, and spacing pitch D3 of the divided pieces 61' are designed to prevent tearing of the uncoated portion D4 near the notch valley during bending of the uncoated portion 43 and to ensure sufficient welding strength by sufficiently increasing the number of overlapping layers of the uncoated portion 43 while preventing abnormal deformation of the uncoated portion 43.

[0152] Preferably, the width D1 of the segment 61' can be adjusted within a range of 1 mm to 6 mm. If D1 is less than 1 mm, when the segment 61' is bent toward the core, the segment 61' will not overlap to an extent sufficient to ensure sufficient welding strength, or an empty space (gap) will be generated. On the other hand, if D1 exceeds 6 mm, the curvature of the wound electrode may cause stress to tear the uncoated portion D4 near the notch valley when the segment 61' is bent. Furthermore, the height of the segment 61' can be adjusted within a range of 2 mm to 10 mm. If D2 is less than 2 mm, the segment 61' may not be bent smoothly, or when the segment 61' is bent toward the core, the segment 61' will not overlap to an extent sufficient to ensure sufficient welding strength, or an empty space (gap) will be generated. On the other hand, if D2 exceeds 10 mm, it is difficult to manufacture an electrode plate while maintaining uniform flatness of the uncoated portion 43 in the winding direction. Furthermore, the spacing pitch D3 of the segment pieces 61' can be adjusted within a range of 0.05 mm to 1 mm or 0.5 mm to 1 mm. If D3 is less than 0.05 mm, stress may be applied when the segment pieces 61' are bent, causing the uncoated portions D4 near the notch valleys to break. On the other hand, if D3 exceeds 1 mm, the segment pieces 61' may not overlap enough to ensure sufficient welding strength when bent, or empty spaces (gaps) may be generated.

[0153] When the segments are trapezoidal, the separation pitch D3 may be defined as the distance between the corners of two adjacent segments 61'. The corners of the two adjacent segments may be connected in a straight line. That is, the bottom of the cut groove may be a flat, straight line extending in the winding direction X.

[0154] The corners may further be provided with rounded reinforcement portions, thereby eliminating stress concentration that may occur at the corners.

[0155] The radius r of the round reinforcing portion may be 0.02 mm or more, which can reliably provide the effect of stress dispersion.

[0156] The radius of the round reinforcing portion may be 0.1 mm or less. If the radius exceeds 0.1 mm, the effect of stress dispersion will not be further increased, and the space near the bottom of the cut groove will be reduced, which may hinder the impregnation of the electrolyte.

[0157] The spacing pitches C3 and D3 may be determined in relation to the widths C1 and D1 of the adjacent segments 61 and 61' defined therein, measured in the winding direction. For example, it is preferable that the spacing pitch between the segments increases as the width of the segments increases in the winding direction. This allows for uniform distribution of electrolyte impregnation along the winding direction of the electrode assembly.

[0158] The width of the segment in the winding direction may be set to gradually increase from the core side toward the outer periphery of the electrode assembly. The width of the segment in the winding direction may increase gradually or stepwise from the core side toward the outer periphery of the electrode assembly. For example, the widths C1 and D1 of the segment in the winding direction may be within a range of 1 mm to 6 mm, decreasing toward the core side and increasing toward the outer periphery.

[0159] Accordingly, the spacing pitches C3 and D3 may also be within a range of 0.5 mm to 1 mm, and may increase gradually or stepwise from the core side to the outer periphery side of the electrode assembly.

[0160] In the fifth embodiment, the lower interior angle θ of the trapezoid of the plurality of segment pieces 61′ may increase from the core side toward the outer periphery. As the radius of the electrode assembly increases, the radius of curvature also increases. If the lower interior angle θ of the segment pieces 61′ increases with the radius of the electrode assembly, stresses occurring in the radial and circumferential directions when the segment pieces 61′ are bent can be alleviated. Furthermore, as the lower interior angle θ increases, the overlapping area and number of overlapping layers with the inner segment pieces 61′ when the segment pieces 61′ are bent also increase, thereby ensuring uniform welding strength in the radial and circumferential directions and enabling the bent surfaces to be formed flat.

[0161] In one example, when electrode plate 70 is used to manufacture an electrode assembly for a cylindrical cell with a form factor of 46800, the interior angle of segment 61' may increase stepwise in the range of 60° to 85° as the radius of the electrode assembly increases from 4 mm to 22 mm.

[0162] In another example, the height of the outer plain portion B3 may decrease gradually or in steps, as in the first and second embodiments. The divided structure of the intermediate plain portion B2 may extend to the outer plain portion B3 (see dotted lines). In this case, the outer plain portion B3 may also include multiple divided segments, similar to the intermediate plain portion B2. In this case, the divided segments of the outer plain portion B3 may have a greater width, height, and / or spacing pitch than the intermediate plain portion B2.

[0163] When the middle plain portion B2 includes a plurality of segments 61, 61' as in the fourth and fifth embodiments, the shape of each segment 61, 61' can be changed to a triangle, semicircle, semi-ellipse, parallelogram, or the like.

[0164] The shapes of the segments 61, 61' may also be varied for each region of the intermediate plain portion B2. For example, a round shape (e.g., semicircular, semi-elliptical, etc.) that is advantageous for stress dispersion may be applied to the section where stress is concentrated, and a polygonal shape (e.g., rectangular, trapezoidal, parallelogram, etc.) with the largest possible area may be applied to the section where stress is relatively low.

[0165] In the fourth and fifth embodiments, the division structure of the middle uncoated portion B2 can also be applied to the core-side uncoated portion B1. However, if a division structure is applied to the core-side uncoated portion B1, there is a risk of reverse forming, in which the ends of the core-side uncoated portion B1 bend toward the outer periphery when the division segments 61, 61' of the middle uncoated portion B2 are bent depending on the radius of curvature of the core. Therefore, it is preferable not to apply a division structure to the core-side uncoated portion B1, or even if a division structure is applied, to adjust the width, height, and / or spacing of the division segments 61, 61' to a level that does not cause reverse forming, taking into account the radius of curvature of the core.

[0166] The height of the segment where such reverse forming can occur may be less than about 3 mm. In addition, if the height of the segment is less than 2 mm, the segment and the separator interfere with each other, making it difficult to bend. In addition, if the height of the segment is less than 4 mm, the welding process of the segment does not proceed smoothly. Therefore, the minimum height (H min ) may be 2 mm or more, 3 mm or more, 4 mm or more, or 5 mm or more. Thus, the height of the minimum bending segment may be 2 mm or more, 3 mm or more, 4 mm or more, or 5 mm or more.

[0167] Therefore, the minimum height at which the plain part can be folded (H min If the second side of the separation membrane is located within a range of ±30% of the height Ha of the smallest bending segment that can be folded among segments having a height of at least 2 mm, 3 mm, 4 mm, or 5 mm (for example, the above-mentioned 2 mm, 3 mm, 4 mm, or 5 mm), impregnation can be significantly improved. In other words, when determining the smallest bending segment that defines the position of the second side of the separation membrane, segments that may cause reverse forming or segments that cannot be folded can be excluded.

[0168] From another perspective, the height Ha of the minimum bending piece in the plain area and the minimum height (H min ) the largest value {max(Ha,H min If the second side of the separation membrane is within a range of ±30% of the above { )}, the impregnation property can be significantly improved.

[0169] From another perspective, the minimum height at which it can be folded (H min ), electrolyte impregnation can be significantly improved. This can be within the range of ±1.5 mm from the boundary between the uncoated portion and the electrode active material portion, ±1.2 mm from the boundary between the uncoated portion and the electrode active material portion, ±0.9 mm from the boundary between the uncoated portion and the electrode active material portion, or ±0.6 mm from the boundary between the uncoated portion and the electrode active material portion.

[0170] Alternatively, the position of the second side of the separation membrane may be within a range of the boundary ±0.3H and the boundary ±1.5mm, or within a range of the boundary ±0.3H and the boundary ±1.2mm, or within a range of the boundary ±0.3H and the boundary ±0.9mm, or within a range of the boundary ±0.3H and the boundary ±0.6mm.

[0171] In the above-described embodiment (variant), the first electrode plate may be a positive electrode plate and the second electrode plate may be a negative electrode plate. Alternatively, the first electrode plate may be a negative electrode plate and the second electrode plate may be a positive electrode plate. In a specific embodiment of the present invention, the first electrode plate may be a positive electrode plate and the second electrode plate may be a negative electrode plate.

[0172] In one embodiment of the present invention, the positive electrode active material coated on the positive electrode plate and the negative electrode active material coated on the negative electrode plate may be any active material known in the art without limitation.

[0173] The positive electrode active material is a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; 1+x Mn2-x Lithium manganese oxides such as O4 (x=0~0.33), LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O5, LiV3O4, V2O5, and Cu2V2O7; chemical formula LiNi 1-x M x Lithium nickel oxide with nickel site structure represented by O2 (M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, x = 0.01 to 0.3); chemical formula: LiMn 2-x M x Examples of the oxides include, but are not limited to, lithium manganese composite oxides represented by Li2Mn3MO8 (M=Fe, Co, Ni, Fe, Cr, Zn, or Ta, x=0.01 to 0.1) or Li2Mn3MO8 (M=Fe, Co, Ni, Cu, or Zn); LiMn2O4 in which part of the lithium in the chemical formula is substituted with an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, or composite oxides formed by a combination of these, which have a lithium intercalation material as the main component.

[0174] The positive electrode current collector has a thickness of, for example, 3 μm to 500 μm. Such a positive electrode current collector is not particularly limited as long as it does not induce chemical changes in the battery and is conductive. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. The electrode current collector may have fine irregularities on its surface to increase the adhesive strength of the positive electrode active material, and may be used in various forms such as a film, sheet, foil, net, porous material, foam, or nonwoven fabric.

[0175] A conductive material may be further mixed with the positive electrode active material particles. The conductive material may be added, for example, in an amount of 1 to 50% by weight based on the total weight of the mixture containing the positive electrode active material. The conductive material may be any material that does not induce chemical changes in the battery and has high conductivity. Examples of such a conductive material include graphite such as natural graphite and artificial graphite; carbon blacks such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber and metal fiber; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0176] Meanwhile, in one embodiment of the present invention, the negative electrode plate is fabricated by coating and drying negative electrode active material particles on a negative electrode current collector, and may further include components such as the above-mentioned conductive material, binder, and solvent, as necessary.

[0177] The negative electrode current collector has a thickness of, for example, 3 μm to 500 μm. Such a negative electrode current collector is not particularly limited as long as it does not induce chemical changes in the battery and is conductive, and examples of such a negative electrode current collector include copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloys. Similarly to the positive electrode current collector, the surface may be formed with fine irregularities to strengthen the binding force of the negative electrode active material, and the negative electrode current collector may be used in various forms such as a film, sheet, foil, net, porous material, foam, or nonwoven fabric.

[0178] The negative electrode active material is, for example, carbon such as non-graphitizable carbon or graphite-based carbon; 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, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8) metal composite oxides; lithium metal; lithium alloys; silicon-based alloys; tin-based alloys; oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials, etc. can be used.

[0179] The binder polymer that can be used for the electrode is a component that assists in the binding of electrode active material particles and conductive materials, etc., and the binding to the electrode current collector. For example, it is added at 1 wt% to 50 wt% based on the total weight of the mixture containing the electrode active material. Such binder polymers include any one binder polymer selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, and carboxymethyl cellulose, or a mixture of two or more of these can be used, but it is not limited thereto.

[0180] Non-limiting examples of the solvent used in the production of the electrode include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or a mixture thereof, etc. Such a solvent provides an appropriate level of viscosity so that a slurry coating layer is formed at a desired level on the surface of the electrode current collector.

[0181] The negative electrode plate includes a current collector and a negative electrode active material portion of a predetermined thickness located on at least one surface of the current collector and including a negative electrode active material, a binder polymer, and a conductive material, the negative electrode active material portion including a lower layer region in surface contact with the current collector and an upper layer region in surface contact with the lower layer region and extending to a surface of the negative electrode active material portion, and the lower layer region and the upper layer region may each independently include at least one of graphite and a silicon-based compound as the negative electrode active material.

[0182] The lower layer region may contain natural graphite as the negative electrode active material, and the upper layer region may contain artificial graphite as the negative electrode active material.

[0183] The lower layer region and the upper layer region may each independently further include a silicon-based compound as a negative electrode active material.

[0184] The silicon-based compound may include one or more of SiOx (0≦x≦2) and SiC.

[0185] According to an embodiment of the present invention, the negative electrode may be manufactured by coating a lower layer slurry containing a lower layer negative electrode active material on a current collector and drying the slurry to form a lower layer region, and then coating an upper layer slurry containing an upper layer negative electrode active material on the lower layer region and drying the slurry to form an upper layer region.

[0186] Alternatively, according to an embodiment of the present invention, the negative electrode may include a step of preparing a lower layer slurry including a lower layer negative electrode active material and an upper layer slurry including an upper layer negative electrode active material; coating one surface of a negative electrode current collector with the lower layer slurry, and simultaneously or after a predetermined time interval, coating the upper layer slurry on the lower layer slurry; and drying the coated lower layer slurry and upper layer slurry simultaneously to form the active material portion.

[0187] In the latter method, a mixed region (intermixing) of different active materials may exist at the contact point between the lower and upper layers of the negative electrode. This is because, when a lower layer slurry containing a lower layer negative electrode active material and an upper layer slurry containing an upper layer negative electrode active material are coated simultaneously or successively with a very short time interval on a current collector and then simultaneously dried to form an active material portion, a predetermined mixed region is formed at the interface where the lower layer slurry and the upper layer slurry contact each other before drying, and this mixed region is then formed in the form of a layer during drying.

[0188] In the negative active material part according to an embodiment of the present invention, the weight ratio (or ratio of loading amount per unit area) of the upper layer region to the lower layer region may be 20:80 to 50:50, and more specifically, 25:75 to 50:50.

[0189] The thicknesses of the lower and upper regions of the negative electrode active material part according to an embodiment of the present invention may not be exactly the same as the thicknesses of the coated lower layer slurry and the coated upper layer slurry, but the thickness ratio of the lower and upper regions of the negative electrode active material part according to an embodiment of the present invention finally obtained after the drying or optional rolling process may be the same as the thickness ratio of the coated lower layer slurry and the coated upper layer slurry.

[0190] According to one embodiment of the present invention, a first slurry (slurry for the lower layer) is coated, and then a second slurry (slurry for the upper layer) is coated on the first slurry simultaneously or after a predetermined time lag. The predetermined time lag may be 0.6 seconds or less, 0.02 to 0.6 seconds, 0.02 to 0.06 seconds, or 0.02 to 0.03 seconds. Since the time lag between the coating of the first and second slurries is caused by the coating equipment, it is more preferable to coat the first and second slurries simultaneously. The second slurry may be coated on the first slurry using an apparatus such as a double slot die.

[0191] The step of forming the active material layer may further include a step of rolling the active material part after the drying step, wherein the rolling may be performed by a method commonly used in the art, such as a roll press, at a pressure of 1 MPa to 20 MPa and a temperature of 15°C to 30°C.

[0192] The step of simultaneously drying the coated lower layer slurry and upper layer slurry to form the active material portion may be performed by a method commonly used in the art using a device that combines a hot air dryer and an infrared dryer.

[0193] The weight % of the first binder polymer in the solid content of the lower layer slurry may be equal to or greater than the weight % of the second binder polymer in the solid content of the upper layer slurry. According to one embodiment of the present invention, the weight % of the first binder polymer in the solid content of the lower layer slurry may be 1.0 to 4.2 times, 1.5 to 3.6 times, or 1.5 to 3 times the weight % of the second binder polymer in the solid content of the upper layer slurry.

[0194] When the ratio of the weight percentage of the first binder in the coated lower layer slurry to the weight percentage of the second binder in the coated upper layer slurry satisfies this range, the binder in the lower layer region does not become too small, so detachment of the electrode layer does not occur, and the binder in the upper layer region does not become too large, so the resistance of the upper layer of the electrode decreases, which is advantageous for fast charging performance.

[0195] The weight percentage of the first binder polymer in the solid content of the lower layer slurry may be 2 wt% to 30 wt%, 5 wt% to 20 wt%, or 5 wt% to 20 wt%, and the weight percentage of the second binder polymer in the solid content of the upper layer slurry may be 0.5 wt% to 20 wt%, 1 wt% to 15 wt%, 1 wt% to 10 wt%, or 2 wt% to 5 wt%.

[0196] The total ratio (wt %) of the first binder polymer and the second binder polymer to the total solid content of the lower layer slurry and the upper layer slurry may be 2 wt % to 20 wt %, or 5 wt % to 15 wt %.

[0197] The separator includes a porous polymer substrate and a porous coating layer disposed on at least one surface or both surfaces of the porous polymer substrate, the porous coating layer including inorganic particles and a binder polymer.

[0198] The porous polymer substrate may be a polyolefin-based porous substrate.

[0199] The polyolefin-based porous substrate may be in the form of a film or a non-woven web. The porous structure facilitates the movement of electrolyte between the positive and negative electrodes, increases the electrolyte impregnation of the substrate itself, ensures excellent ionic conductivity, and prevents an increase in resistance within the electrochemical device, thereby preventing a decrease in the performance of the electrochemical device.

[0200] The polyolefin-based porous substrate used in the present invention can be any planar porous substrate that is commonly used in electrochemical elements, and the material and shape thereof can be selected from a variety of materials depending on the purpose.

[0201] The polyolefin-based porous substrate may be, but is not limited to, a film or nonwoven web formed from high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, or a mixture of two or more of these.

[0202] The polyolefin-based porous substrate may have a thickness of 8 μm to 30 μm, but this is merely an example, and thicknesses outside the above range may be adopted in consideration of mechanical properties and high-rate charge / discharge characteristics of the battery.

[0203] The nonwoven fabric sheet according to one embodiment of the present invention may be made of polyethylene (PE), polypropylene (PP), or a mixture thereof. For example, the nonwoven fabric sheet may be manufactured by fiber spinning. For example, the nonwoven fabric sheet may be manufactured by blending and spinning material fibers at or above their melting points using a melt-blown method.

[0204] The nonwoven fabric sheet may have an elongation ratio of 200% to 400%, more preferably 300% to 400%. If the elongation ratio is less than 200%, the electrodes are more likely to come into contact with each other when a nail penetrates the sheet, whereas if the elongation ratio exceeds 400%, the peripheral portions of the sheet are also elongated when a nail penetrates the sheet, making the separation membrane thinner and reducing its barrier properties (blocking properties).

[0205] The nonwoven fabric sheet has a large number of pores with an average diameter of 0.1 μm to 10 μm. If the pore size is smaller than 0.1 μm, lithium ions and / or the electrolyte cannot move smoothly, and if the pore size is larger than 10 μm, the nonwoven fabric sheet may stretch when a nail penetrates, which may prevent contact between the positive electrode and the negative electrode, and this may not be an effect of the present invention.

[0206] The nonwoven fabric sheet may have a porosity of 40% to 70%. If the porosity is less than 40%, lithium ions and / or the electrolyte may not move smoothly, and if the porosity is greater than 70%, the effect of one embodiment of the present invention, which aims to prevent contact between the positive and negative electrodes, may not be achieved due to the stretching of the nonwoven fabric sheet when a nail penetrates. The nonwoven fabric sheet manufactured in this manner may have an air permeability of 1 sec / 100 mL to 20 sec / 100 mL.

[0207] The nonwoven fabric sheet may have a thickness of 10 μm to 20 μm, but this is merely an example and is not limited to this. A nonwoven fabric sheet having a thickness outside the above range may also be adopted depending on the permeability of the nonwoven fabric sheet.

[0208] The nonwoven fabric sheet can be bonded to the separator component below the nonwoven fabric sheet by lamination. Lamination can be performed at a temperature ranging from 100 to 150°C. However, if lamination is performed at a temperature lower than 100°C, the lamination effect will not be achieved, and if lamination is performed at a temperature higher than 150°C, there is a risk of partial melting of the nonwoven fabric.

[0209] The separator according to one embodiment of the present invention bonded by lamination under the above conditions has improved resistance to nail penetration compared to a separator made of a conventional nonwoven fabric sheet, and compared to a separator having a layer containing inorganic particles formed on at least one surface of a film or nonwoven fabric sheet.

[0210] In the porous coating layer, the inorganic particles are packed together and in contact with each other and bound by the binder polymer, thereby forming interstitial volumes between the inorganic particles, which may become empty spaces and form pores.

[0211] The inorganic particles used to form the porous coating layer are inorganic particles, i.e., particles that are within the operating voltage range (e.g., Li / Li + Inorganic particles that do not undergo oxidation and / or reduction reactions at a voltage (0V to 5V based on the reference voltage) may be further added. In particular, when inorganic particles having ion conductivity are used, the ionic conductivity in the electrochemical device can be increased, thereby improving performance. Furthermore, when inorganic particles having a high dielectric constant are used as the inorganic particles, they can contribute to increasing the degree of dissociation of electrolyte salts, such as lithium salts, in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte solution.

[0212] For the reasons mentioned above, the inorganic particles preferably include inorganic particles with a high dielectric constant having a dielectric constant of 5 or more, preferably 10 or more, inorganic particles having lithium ion conductivity, or a mixture thereof.

[0213] Non-limiting examples of inorganic particles having a dielectric constant of 5 or more include BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3 (PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiC, aluminum hydroxides such as boehmite (γ-AlO(OH)), pseudoboehmite (Al2O3·H2O), diaspore (α-AlO(OH)), bayerite (α-AlO(OH)3), gibbsite (γ-AlO(OH)3), nordstrandite (AlO(OH)3), or mixtures thereof.

[0214] In particular, the above-mentioned BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg 1 / 3 Nb 2 / 3 Inorganic particles such as )O3-PbTiO3 (PMN-PT) and hafnia (HfO2) not only exhibit high dielectric constants of over 100, but also possess piezoelectricity, which generates a potential difference between the two surfaces when stretched or compressed under a certain pressure, preventing internal short circuits between the electrodes due to external impacts and improving the safety of electrochemical devices. Furthermore, when inorganic particles with high dielectric constants are used in combination with inorganic particles with lithium ion transport properties, the synergistic effects are multiplied.

[0215] Inorganic particles having lithium ion conductivity refer to inorganic particles that contain lithium elements but do not store lithium and have the function of moving lithium ions. Inorganic particles having lithium ion conductivity can transmit and move lithium ions due to a kind of defect existing inside the particle structure, so the lithium ion conductivity in the battery is improved, and thereby the battery performance can be enhanced. Non-limiting examples of the inorganic particles having lithium ion conductivity include lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 < x < 2, 0 < y < 3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO4)3, 0 < x < 2, 0 < y < 1, 0 < z < 3), (LiAlTiP) x O y -based glasses such as 14Li2O - 9Al2O3 - 38TiO2 - 39P2O5 (where 0 < x < 4, 0 < y < 13), lithium lanthanum titanate (Li x La y TiO3, 0 < x < 2, 0 < y < 3), lithium germanium thiophosphate such as Li 3.25 Ge 0.25 P 0.75 S4 (where 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), lithium nitride such as Li3N (Li x N y , 0 < x < 4, 0 < y < 2), SiS2 - based glasses such as Li3PO4 - Li2S - SiS2 (Li x Si y S z , 0 < x < 3, 0 < y < 2, 0 < z < 4), P2S5 - based glasses such as LiI - Li2S - P2S5 (Li x P y S z , 0 < x < 3, 0 < y < 3, 0 < z < 7) or mixtures thereof, and the like.

[0216] ​​​​​​​​ In one embodiment of the present invention, the inorganic particles may include hydrophilic inorganic particles. Examples of hydrophilic inorganic particles include Al2O3 or aluminum hydroxide-based inorganic particles. Examples of the aluminum hydroxide-based inorganic particles include boehmite (γ-AlO(OH)), pseudoboehmite (Al2O3·H2O), diaspore (α-AlO(OH)), bayerite (α-AlO(OH)3), gibbsite (γ-AlO(OH)3), and nordstrandite (AlO(OH)3). In one embodiment of the present invention, the separator may include one or more of these hydrophilic inorganic particles. In particular, when a hydrophilic organic solvent, such as a carbonate-based organic solvent, is used as the organic solvent for the electrolyte, applying these hydrophilic inorganic particles to the porous coating layer of the separator can further improve the electrolyte impregnation of the electrode assembly. In one embodiment of the present invention, when a separator substrate made of a polyolefin-based material is used, it is difficult to ensure sufficient wettability with the electrolyte due to its hydrophobicity. In this case, applying hydrophilic inorganic particles to the porous coating layer formed on the surface can prevent the separator from having low wettability due to the hydrophobicity of the polyolefin-based separator substrate. The size of the inorganic particles in the porous coating layer is not limited, but is preferably 0.001 μm to 10 μm to form a coating layer of uniform thickness and achieve appropriate porosity. If the size is less than 0.001 μm, the dispersibility of the inorganic particles decreases. If the size exceeds 10 μm, the thickness of the porous coating layer increases, resulting in reduced mechanical properties and excessively large pore size, which can potentially cause internal short circuits during battery charging and discharging.

[0217] Meanwhile, the binder polymer forming the porous coating layer may be any one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, and carboxymethyl cellulose, or a mixture of two or more thereof, but is not limited thereto.

[0218] The composition ratio of inorganic particles to binder polymer used in the porous coating layer is preferably, for example, in the range of 50:50 to 99:1, and more preferably 70:30 to 95:5. If the content of inorganic particles relative to binder polymer is less than 50 parts by weight, the content of binder polymer will be too high, which may reduce the improvement in the thermal stability of the separator. Furthermore, the reduction in the void space formed between the inorganic particles may reduce the pore size and porosity, resulting in a deterioration in final battery performance. If the content of inorganic particles exceeds 99 parts by weight, the content of binder polymer will be too low, which may weaken the peel resistance of the porous coating layer.

[0219] The thickness of the porous coating layer is not particularly limited, but is preferably 0.01 μm to 20 μm. The pore size and porosity are also not particularly limited, but the pore size is preferably 0.001 μm to 10 μm, and the porosity is preferably 10% to 90%. The pore size and porosity depend primarily on the size of the inorganic particles. For example, when inorganic particles with a particle size of 1 μm or less are used, the formed pores will also be approximately 1 μm or less. This pore structure is filled with the electrolyte solution that is subsequently injected, and the filled electrolyte solution functions as an ion transport layer. If the pore size and porosity are less than 0.001 μm and 10%, respectively, the layer will function as a resistive layer, while if they exceed 10 μm and 90%, respectively, the mechanical properties may be reduced.

[0220] The porous coating layer can be formed by dissolving or dispersing a binder polymer in a dispersion medium, adding inorganic particles to the dispersion medium to obtain a slurry for forming the porous coating layer, and then coating and drying the slurry on at least one surface of the substrate. The dispersion medium preferably has a solubility index similar to that of the binder polymer to be used and a low boiling point. This facilitates uniform mixing and subsequent removal of the dispersion medium. Non-limiting examples of suitable dispersion mediums include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, and mixtures thereof.

[0221] It is preferable to add inorganic particles to a dispersion in which the binder polymer is dispersed in a dispersion medium, and then crush the inorganic particles. In this case, the crushing time is preferably 1 to 20 hours, and the size of the crushed inorganic particles is preferably 0.001 μm to 10 μm, as described above. As a crushing method, a conventional method can be used, and a ball mill method is particularly preferable.

[0222] The binder polymer dispersion containing the dispersed inorganic particles is then coated onto at least one surface of a porous polymer substrate under a humidity condition of 10% to 80% and dried. The method for coating the dispersion onto the porous polymer substrate may be a conventional coating method well known in the art, such as dip coating, die coating, roll coating, comma coating, or a combination thereof.

[0223] In addition to the inorganic particles and binder polymer described above, the porous coating layer may further include other additives such as a conductive material.

[0224] The separator finally manufactured according to one embodiment of the present invention may have a thickness of 1 μm to 100 μm or 5 μm to 50 μm. If the thickness is less than 1 μm, the separator may not function properly and mechanical properties may deteriorate, while if the thickness exceeds 100 μm, battery properties may deteriorate during high-rate charge / discharge. The separator may also have a porosity of 40% to 60% and an air permeability of 150 sec / 100 mL to 300 sec / 100 mL.

[0225] According to an embodiment of the present invention, the porous polymer substrate may be made of polyethylene or polypropylene, and the inorganic particles in the porous coating layer may be made of Al oxide or Si oxide coating materials.

[0226] When using a separator according to an embodiment of the present invention, the porous coating layers are provided on both sides of the porous polymer substrate, which improves the electrolyte impregnation performance and allows for the formation of a uniform solid electrolyte interfacial layer, thereby ensuring superior air permeability compared to conventional single-sided inorganic-coated separators. For example, the air permeability may be within 120 s / 100 cc. Furthermore, even though inorganic porous coating layers are provided on both sides, the thickness can be the same as that of conventional single-sided inorganic-coated separators. For example, the thickness may be within 15.0 μm.

[0227] Furthermore, when a separator according to an embodiment of the present invention is used, the separator's stability is improved, ensuring heat resistance and compression resistance. Specifically, the separator can have heat resistance with a thermal shrinkage of 5% or less at 180°C, and can have a puncture strength of 550 gf or more. When core deformation occurs during cycling of a battery using such a separator, damage or puncture of the separator at the step can be prevented.

[0228] Hereinafter, the structure of an electrode assembly according to an embodiment of the present invention will be described in detail.

[0229] FIG. 11 is a cross-sectional view of a jelly-roll type electrode assembly 80 according to an embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0230] The electrode assembly 80 can be manufactured by the winding method described with reference to Fig. 2. For ease of explanation, the protruding structure of the uncoated portions 43a and 43b extending outward from the separator is shown in detail, and the winding structure of the first electrode plate, the second electrode plate, and the separator is not shown. In the drawing, the uncoated portion 43a protruding upward extends from the first electrode plate, and the uncoated portion 43b protruding downward extends from the second electrode plate.

[0231] 12 to 16 show schematic diagrams of patterns in which the heights of the uncoated portions 43a, 43b vary. That is, the heights of the uncoated portions 43a, 43b may vary irregularly depending on the cutting position of the cross section. For example, if the sides of the trapezoidal segments 61, 61' are cut, the height of the uncoated portions in the cross section will be lower than the height of the segments 61, 61'. Therefore, it should be understood that the heights of the uncoated portions 43a, 43b shown in the drawings showing the cross sections of the electrode assembly correspond to the average height of the uncoated portions included in each winding turn (C2 in FIG. 10a, D2 in FIG. 10b).

[0232] Referring to Figure 11, the uncoated portion 43a of the first electrode plate includes a core-side uncoated portion B1 adjacent to the core of the electrode assembly 80, an outer-periphery-side uncoated portion B3 adjacent to the outer peripheral surface of the electrode assembly 80, and an intermediate uncoated portion B2 interposed between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0233] The height (length in the Y-axis direction) of the outer uncoated portion B3 is relatively shorter than the height of the middle uncoated portion B2, which prevents the outer uncoated portion B3 from being pressed against the beading portion of the battery can, thereby preventing an internal short circuit from occurring.

[0234] Here, the lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one modified embodiment, the lower uncoated portion 43b may have a conventional electrode plate structure or an electrode plate structure of another embodiment (modified embodiment).

[0235] In addition, the ends 81 of the upper uncoated portion 43a and the lower uncoated portion 43b may be bent from the outer periphery toward the core of the electrode assembly 80. In this case, the outer periphery uncoated portion B3 may not be substantially bent.

[0236] FIG. 12 is a cross-sectional view of a jelly-roll type electrode assembly 90 in which the electrode plate 45 of the second embodiment is applied to the first and second electrode plates, taken along the Y-axis direction (winding axis direction).

[0237] Referring to Figure 12, the uncoated portion 43a of the first electrode plate includes a core-side uncoated portion B1 adjacent to the core of the electrode assembly 90, an outer-periphery-side uncoated portion B3 adjacent to the outer peripheral surface of the electrode assembly 90, and an intermediate uncoated portion B2 interposed between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0238] The height of the outer uncoated portion B3 is relatively lower than the height of the middle uncoated portion B2, and decreases gradually or in steps from the core side to the outer periphery, thereby preventing the outer uncoated portion B3 from being pressed against the beading of the battery can, which could cause an internal short circuit.

[0239] Here, the lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one modified embodiment, the lower uncoated portion 43b may have a conventional electrode plate structure or an electrode structure of another embodiment (modified embodiment).

[0240] In addition, the ends 91 of the upper uncoated portion 43a and the lower uncoated portion 43b may be bent from the outer periphery toward the core of the electrode assembly 90. In this case, the outermost portion 92 of the outer periphery uncoated portion B3 may not be substantially bent.

[0241] FIG. 13 is a cross-sectional view of a jelly-roll type electrode assembly 100 in which any one of the electrode plates 50, 60, 70 of the third to fifth embodiments (modifications thereof) is applied to the first electrode plate (positive electrode plate) and the second electrode plate (negative electrode plate) along the Y-axis direction (winding axis direction).

[0242] Referring to Figure 13, the uncoated portion 43a of the first electrode plate includes a core-side uncoated portion B1 adjacent to the core of the electrode assembly 100, an outer-periphery-side uncoated portion B3 adjacent to the outer peripheral surface of the electrode assembly 100, and an intermediate uncoated portion B2 interposed between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0243] The height of the core-side uncoated region B1 is relatively lower than that of the intermediate uncoated region B2. The height of the innermost uncoated region 43a in the intermediate uncoated region B2 is equal to or shorter than the radial length R of the core-side uncoated region B1.

[0244] Therefore, even if the middle uncoated portion B2 is bent, the bent portion does not block the cavity 102 in the core of the electrode assembly 100. When the cavity 102 is not blocked in this way, the electrolyte injection process is not hindered, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the cavity 102 to easily perform the welding process between the negative electrode current collector plate and the battery can.

[0245] In addition, the height of the outer uncoated portion B3 is relatively lower than the height of the middle uncoated portion B2, which prevents the outer uncoated portion B3 from being pressed against the beading portion of the battery can, thereby preventing an internal short circuit from occurring.

[0246] In one modified embodiment, the height of the outer circumferential plain portion B3 may decrease gradually or in steps, unlike Fig. 13. Also, while the height of the intermediate plain portion B2 is uniform over a portion of the outer circumferential side in Fig. 13, the height of the intermediate plain portion B2 may increase gradually or in steps from the boundary between the core-side plain portion B1 and the intermediate plain portion B2 to the boundary between the intermediate plain portion B2 and the outer circumferential plain portion B3.

[0247] Here, the lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one modified embodiment, the lower uncoated portion 43b may have a conventional electrode plate structure or an electrode structure of another embodiment (modified embodiment).

[0248] Here, the ends 101 of the upper uncoated portion 43a and the lower uncoated portion 43b may be bent from the outer periphery side to the core side of the electrode assembly 100. At this time, the core-side uncoated portion B1 and the outer periphery-side uncoated portion B3 are not substantially bent.

[0249] Here, when the middle uncoated portion B2 includes a plurality of segments, bending stress is alleviated, thereby preventing tearing or abnormal deformation of the notch valley portion of the uncoated portion 43. Furthermore, when the width and / or height and / or spacing pitch of the segments are adjusted within the ranges of the numerical values ​​of the above-mentioned embodiments, the segments are folded toward the core in multiple layers to an extent that sufficient welding strength can be ensured, and no open spaces (gaps) are formed on the folded surface (surface viewed from the Y-axis direction).

[0250] FIG. 14 is a cross-sectional view of an electrode assembly 110 according to another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0251] Referring to Figure 14, the electrode assembly 110 is substantially identical in configuration to the electrode assembly 100 of Figure 13, except that the height of the outer uncoated portion B3 is substantially the same as the outermost height of the middle uncoated portion B2.

[0252] The outer circumferential plain portion B3 may include a plurality of segments. The configuration of the plurality of segments is similarly described in the fourth and fifth embodiments (variations).

[0253] Here, in the electrode assembly 110, the height of the core-side uncoated region B1 is relatively lower than the height of the middle uncoated region B2. In addition, the height H of the innermost uncoated region in the middle uncoated region B2 is equal to or shorter than the radial length R of the core-side uncoated region B1.

[0254] Therefore, even if the middle uncoated portion B2 is bent, the bent portion does not block the cavity 112 in the core of the electrode assembly 110. If the cavity 112 is not blocked, the electrolyte injection process is not hindered, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the cavity 112 to easily perform the welding process between the negative electrode current collector plate and the battery can.

[0255] In one modified embodiment, the structure in which the height of the intermediate uncoated portion B2 increases gradually or in steps from the core side to the outer periphery side may be extended to the outer periphery side uncoated portion B3. In this case, the height of the uncoated portion 43a may increase gradually or in steps from the boundary between the core side uncoated portion B1 and the intermediate uncoated portion B2 to the outermost surface of the electrode assembly 110.

[0256] Here, the lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one modified embodiment, the lower uncoated portion 43b may have a conventional electrode plate structure or an electrode structure of another embodiment (modified embodiment).

[0257] The ends 111 of the upper uncoated portion 43a and the lower uncoated portion 43b may be bent from the outer periphery side to the core side of the electrode assembly 110. At this time, the core-side uncoated portion B1 is not substantially bent.

[0258] When the central uncoated region B2 and the outer uncoated region B3 include multiple segments, bending stress is alleviated, preventing tearing or abnormal deformation of the uncoated regions 43a, 43b near the notch valleys. Furthermore, when the width and / or height and / or spacing pitch of the segments are adjusted within the ranges of the above-described embodiments, the segments are folded toward the core in multiple layers to an extent that sufficient welding strength is ensured, and no open spaces (gaps) are formed on the folded surface (surface viewed from the Y-axis direction).

[0259] FIG. 15 is a cross-sectional view of an electrode assembly 120 according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0260] Referring to FIG. 15, the electrode assembly 120 differs from the electrode assembly 100 of FIG. 13 only in that the height of the intermediate plain portion B2 has a pattern in which it gradually or stepwise increases and then decreases, but the other configurations are substantially the same.

[0261] Such a change in the height of the middle plain portion B2 can be achieved by adjusting the height of the staircase pattern (see FIG. 6) or the division pieces (see FIG. 7a or 7b) included in the middle plain portion B2.

[0262] In the electrode assembly 120, the height of the core-side uncoated area B1 is relatively lower than the height of the intermediate uncoated area B2. In addition, the height H of the innermost uncoated area in the intermediate uncoated area B2 is equal to or shorter than the radial length R of the core-side uncoated area B1.

[0263] Therefore, even if the middle uncoated portion B2 is bent toward the core side, the bent portion does not block the cavity 122 in the core of the electrode assembly 120. If the cavity 122 is not blocked, the electrolyte injection process is not hindered, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the cavity 122 to easily perform the welding process between the negative electrode current collector plate and the battery can.

[0264] In addition, the height of the outer uncoated portion B3 is relatively lower than the height of the middle uncoated portion B2. This prevents the outer uncoated portion B3 from being pressed against the beading of the battery can, which could cause an internal short circuit. In one modified embodiment, the height of the outer uncoated portion B3 may decrease gradually or in steps toward the outer periphery.

[0265] Here, the lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In a modified embodiment, the lower uncoated portion 43b may have a conventional electrode plate structure or an electrode structure of another embodiment (modified embodiment).

[0266] Here, the ends 121 of the upper uncoated portion 43a and the lower uncoated portion 43b may be bent from the outer periphery side to the core side of the electrode assembly 120. At this time, the core-side uncoated portion B1 and the outer periphery-side uncoated portion B3 are not substantially bent.

[0267] When the middle uncoated portion B2 includes a plurality of segments, bending stress is alleviated, thereby preventing tearing or abnormal deformation of the uncoated portions 43a, 43b. Furthermore, when the width and / or height and / or spacing pitch of the segments are adjusted within the ranges of the above-described embodiments, the segments are folded toward the core in multiple layers to a degree that ensures sufficient welding strength, and no open spaces (gaps) are formed on the folded surface (surface viewed from the Y-axis direction).

[0268] FIG. 16 is a cross-sectional view of an electrode assembly 130 according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0269] Referring to Figure 16, the electrode assembly 130 differs from the electrode assembly 120 of Figure 15 in that the height of the outer uncoated portion B3 gradually or stepwise decreases from the boundary between the outer uncoated portion B3 and the intermediate uncoated portion B2 toward the outermost surface of the electrode assembly 130; other configurations are substantially the same.

[0270] This height variation of the outer plain portion B3 can be achieved by extending the staircase pattern (see FIG. 6) included in the intermediate plain portion B2 to the outer plain portion B3 and gradually or stepwise decreasing the height of the pattern toward the outer periphery. In another modified embodiment, the height variation of the outer plain portion B3 can be achieved by extending the segment structure of the intermediate plain portion B2 to the outer plain portion B3 and gradually or stepwise decreasing the height of the segment toward the outer periphery.

[0271] In the electrode assembly 130, the height of the core-side uncoated region B1 is relatively lower than the height of the middle uncoated region B2. In addition, the height H of the innermost uncoated region in the middle uncoated region B2 is equal to or shorter than the radial length R of the core-side uncoated region B1.

[0272] Therefore, even if the middle uncoated portion B2 is bent toward the core side, the bent portion does not block the cavity 132 of the core of the electrode assembly 120. If the cavity 132 is not blocked, the electrolyte injection process is not hindered, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the cavity 132 to easily perform the welding process between the negative electrode current collector plate and the battery can.

[0273] Here, the lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one modified embodiment, the lower uncoated portion 43b may have a conventional electrode plate structure or an electrode structure of another embodiment (modified embodiment).

[0274] Here, the ends 131 of the upper uncoated portion 43a and the lower uncoated portion 43b may be bent from the outer periphery side to the core side of the electrode assembly 130. At this time, the core-side uncoated portion B1 is not substantially bent.

[0275] When the middle uncoated region B2 and the outer uncoated region B3 include a plurality of segments, bending stress is alleviated, thereby preventing tearing or abnormal deformation of the notch valleys of the uncoated regions 43a, 43b. Furthermore, when the width and / or height and / or spacing pitch of the segments are adjusted within the ranges of the above-described embodiments, the segments are folded toward the core in multiple layers to a degree that ensures sufficient welding strength, and no open spaces (gaps) are formed on the folded surface (surface viewed from the Y-axis direction).

[0276] Various electrode assembly structures according to embodiments of the present invention are applicable to jelly-roll type cylindrical battery cells.

[0277] Preferably, the cylindrical battery cell may be, for example, a cylindrical battery cell having a form factor ratio (defined as the diameter of a cylindrical battery cell divided by its height, i.e., the ratio of height (H) to diameter (Φ)) greater than about 0.4.

[0278] Here, the term "form factor" refers to a value indicating the diameter and height of a cylindrical battery cell. Cylindrical battery cells according to an embodiment of the present invention may be, for example, 46110 cells, 48750 cells, 48110 cells, 48800 cells, or 46800 cells. In the form factor number, 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 cross section of the cell is circular.

[0279] When an electrode assembly having a tabless structure is applied to a cylindrical battery cell having a form factor ratio exceeding 0.4, the stress applied in the radial direction when the plain portion is bent increases, making the plain portion prone to tearing. Furthermore, when welding a current collector plate to the bent surface of the plain portion, the number of overlapping layers of the plain portion must be increased to ensure sufficient welding strength and reduce resistance. These requirements can be met by the electrode plate and electrode assembly according to an embodiment (variant) of the present invention.

[0280] A battery cell according to one embodiment of the present invention may be a cylindrical battery cell that is approximately cylindrical, having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0281] A battery cell according to another embodiment may be a cylindrical battery cell that is a generally cylindrical cell having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of 0.640.

[0282] A battery cell according to yet another embodiment may be a cylindrical battery cell that is substantially cylindrical, having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0283] A battery cell according to yet another embodiment may be a cylindrical battery cell that is substantially cylindrical, having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0284] A battery cell according to yet another embodiment may be a cylindrical battery cell that is substantially cylindrical, having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0285] Conventionally, battery cells with a form factor ratio of approximately 0.4 or less have been used. For example, 18650 cells and 21700 cells have been used. 18650 cells have a diameter of approximately 18 mm, a height of approximately 65 mm, and a form factor ratio of 0.277. 21700 cells have a diameter of approximately 21 mm, a height of approximately 70 mm, and a form factor ratio of 0.300.

[0286] Hereinafter, a cylindrical battery cell according to an embodiment of the present invention will be described in detail.

[0287] FIG. 17 is a cross-sectional view of a cylindrical battery cell 140 according to an embodiment of the present invention taken along the Y-axis direction.

[0288] Referring to FIG. 17, a cylindrical battery cell 140 according to one embodiment of the present invention includes an electrode assembly 141 including a first electrode plate, a separator, and a second electrode plate, a battery can 142 that houses the electrode assembly 141, and a seal 143 that seals the open end of the battery can 142.

[0289] The battery can 142 is a cylindrical container with an opening at the top. The battery can 142 is made of a conductive metal material such as aluminum or steel. The battery can 142 accommodates the electrode assembly 141 in the inner space through the opening at the top, along with the electrolyte.

[0290] The electrolyte is A + B - where A + Li + , Na + , K. + or a combination thereof. - 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 one or more anions selected from the group consisting of:

[0291] The electrolyte may be dissolved in an organic solvent. The organic solvent is not limited to a specific component, as long as it can be used as a solvent for the electrolyte of an electrochemical device. For example, carbonate solvents such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or mixtures thereof may be used.

[0292] The electrode assembly 141 may have a jelly roll structure. As shown in Fig. 2, the electrode assembly 141 may be manufactured by sequentially stacking a lower separator, a first electrode plate, an upper separator, and a second electrode plate at least once, and winding the stack around a winding center C.

[0293] The first and second electrode plates have opposite polarities. That is, one has a positive polarity and the other has a negative polarity. At least one of the first and second electrode plates may have an electrode plate structure according to the above-described embodiment (variant). The other of the first and second electrode plates may have a conventional electrode plate structure or an electrode plate structure according to the embodiment (variant).

[0294] An uncoated portion 146a of the first electrode plate and an uncoated portion 146b of the second electrode plate protrude from the upper and lower portions of the electrode assembly 141, respectively. The first electrode plate has the electrode plate structure of the first embodiment (variant). Therefore, the height of the uncoated portion 146a of the first electrode plate, the outer circumferential uncoated portion B3, is lower than the height of the uncoated portions of other portions. The outer circumferential uncoated portion B3 is spaced a predetermined distance from the inner circumferential surface of the battery can 142, particularly the beading portion 147. Therefore, the outer circumferential uncoated portion B3 of the first electrode plate does not contact the battery can 142, which is electrically connected to the second electrode plate, thereby preventing an internal short circuit in the battery cell 140.

[0295] The uncoated portions 146b of the second electrode plate have the same height. In a modified embodiment, the uncoated portions 146b of the second electrode plate may have the same structure as the uncoated portions 146a of the first electrode plate. In another modified embodiment, the uncoated portions 146b of the second electrode plate may selectively have the structure of the uncoated portions of the electrode plates according to the embodiment (modified embodiment).

[0296] The sealing body 143 may include a cap plate 143a, a first gasket 143b having insulating properties and providing airtightness between the cap plate 143a and the battery can 142, and a connecting plate 143c electrically and mechanically connected to the cap plate 143a.

[0297] The cap plate 143a is a component made of a conductive metal material and covers the upper opening of the battery can 142. The cap plate 143a is electrically connected to the uncoated portion 146a of the first electrode plate and is electrically insulated from the battery can 142 via a first gasket 143b. Therefore, the cap plate 143a can function as a first electrode terminal of the cylindrical battery cell 140.

[0298] The cap plate 143a is placed on a beading portion 147 formed on the battery can 142 and fixed by a crimping portion 148. A first gasket 143b may be interposed between the cap plate 143a and the crimping portion 148 to ensure airtightness of the battery can 142 and to provide electrical insulation between the battery can 142 and the cap plate 143a. The cap plate 143a may have a protrusion 143d formed to protrude upward from the center thereof.

[0299] The battery can 142 is electrically connected to the uncoated portion 146b of the second electrode plate. Therefore, the battery can 142 has the same polarity as the second electrode plate. If the second electrode plate has a negative polarity, the battery can 142 also has a negative polarity.

[0300] The battery can 142 has a beading portion 147 and a crimping portion 148 at its upper end. The beading portion 147 is formed by pressing in around the outer periphery of the battery can 142. The beading portion 147 prevents the electrode assembly 141 housed inside the battery can 142 from slipping out of the upper opening of the battery can 142, and also functions as a support on which the sealing body 143 is placed.

[0301] The inner circumferential surface of the beading portion 147 is spaced a predetermined distance from the outer uncoated portion B3 of the first electrode plate. More specifically, the lower end of the inner circumferential surface of the beading portion 147 is spaced a predetermined distance from the outer uncoated portion B3 of the first electrode plate. Furthermore, because the height of the outer uncoated portion B3 is low, the outer uncoated portion B3 is substantially unaffected even when the battery can 142 is pressed from the outside to form the beading portion 147. Therefore, the outer uncoated portion B3 is not pressed by other components such as the beading portion 147, which prevents partial deformation of the electrode assembly 141 and internal short circuits in the cylindrical battery cell 140.

[0302] Preferably, the relationship "D1≦D2" is satisfied, where D1 is the pressing depth of the beading portion 147 and D2 is the radial distance from the inner circumferential surface of the battery can 142 to the boundary between the outer uncoated portion B3 and the intermediate uncoated portion B2. In this case, damage to the outer uncoated portion B3 is substantially prevented when the battery can 142 is pressed to form the beading portion 147.

[0303] The crimping portion 148 is formed on the upper portion of the beading portion 147. The crimping portion 148 is extended and bent to enclose the outer circumferential surface of the cap plate 143a disposed on the beading portion 147 and a portion of the upper surface of the cap plate 143a.

[0304] The cylindrical battery cell 140 may further include a first current collector 144 and / or a second current collector 145 and / or an insulator 146 .

[0305] The first current collecting plate 144 is coupled to the upper part of the electrode assembly 141. The first current collecting plate 144 is made of a conductive metal material such as aluminum, copper, or nickel, and is electrically connected to the uncoated portion 146a of the first electrode plate. A lead 149 may be connected to the first current collecting plate 144. The lead 149 may be coupled to the connecting plate 143c while extending above the electrode assembly 141, or may be directly coupled to the lower surface of the cap plate 143a. The lead 149 may be coupled to other components by welding.

[0306] Preferably, the first current collector 144 may be integrally formed with the lead 149. In this case, the lead 149 may be in the form of a long plate extending outward from the center of the first current collector 144.

[0307] The first current collecting plate 144 may have a plurality of radially formed concaves and convexes (not shown) on its lower surface. When the radial concaves and convexes are provided, the first current collecting plate 144 may be pressed against the concaves and convexes to press the uncoated portion 146a of the first electrode plate into the concaves and convexes.

[0308] The first current collecting plate 144 is coupled to an end of the uncoated portion 146a of the first electrode plate. The uncoated portion 146a and the first current collecting plate 144 may be coupled together by, for example, laser welding. Laser welding may be performed by partially melting the base material of the current collecting plate. In a modified embodiment, the first current collecting plate 144 and the uncoated portion 146a may be welded together using solder. In this case, the solder may have a lower melting point than the first current collecting plate 144 and the uncoated portion 146a. Laser welding may be replaced by resistance welding, ultrasonic welding, or the like.

[0309] A second current collecting plate 145 may be coupled to the lower surface of the electrode assembly 141. One surface of the second current collecting plate 145 may be coupled to the uncoated portion 146b of the second electrode plate by welding, and the other surface may be coupled to the inner bottom surface of the battery can 142 by welding. The coupling structure between the second current collecting plate 145 and the uncoated portion 146b of the second electrode plate may be substantially the same as the coupling structure between the first current collecting plate 144 and the uncoated portion 146a of the first electrode plate.

[0310] The uncoated portions 146a and 146b are not limited to the structure shown in the drawings. Therefore, the uncoated portions 146a and 146b may selectively have the structure of the uncoated portions of the electrode plates according to the embodiment (variant) as well as the structure of the conventional uncoated portions.

[0311] The insulator 146 may cover the first current collector 144. By covering the first current collector 144 on the upper surface of the first current collector 144, the insulator 146 can prevent direct contact between the first current collector 144 and the inner circumferential surface of the battery can 142.

[0312] The insulator 146 has a lead hole 151 through which the lead 149 extending upward from the first current collector plate 144 is drawn out. The lead 149 is drawn upward through the lead hole 151 and coupled to the lower surface of the connecting plate 143c or the lower surface of the cap plate 143a.

[0313] The peripheral region of the insulator 146 may be interposed between the first current collecting plate 144 and the beading portion 147 to fix the combination of the electrode assembly 141 and the first current collecting plate 144. This limits the movement of the combination of the electrode assembly 141 and the first current collecting plate 144 in the height direction of the battery cell 140, thereby improving the assembly stability of the battery cell 140.

[0314] The insulator 146 may be made of a polymer resin having insulating properties. For example, the insulator 146 may be made of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0315] The battery can 142 may further include a vent 152 formed on its bottom surface. The vent 152 corresponds to a region on the bottom surface of the battery can 142 that is thinner than the surrounding region. The vent 152 is structurally weaker than the surrounding region. Therefore, if an abnormality occurs in the cylindrical battery cell 140 and the internal pressure increases above a certain level, the vent 152 may burst, causing gas generated inside the battery can 142 to be released to the outside.

[0316] The venting portion 152 may be formed continuously or discontinuously in a circle on the bottom surface of the battery can 142. In a variant, the venting portion 152 may be formed in a linear pattern or in any other pattern.

[0317] FIG. 18 is a cross-sectional view of a cylindrical battery cell 150 according to another embodiment of the present invention, taken along the Y-axis direction.

[0318] Referring to FIG. 18, the cylindrical battery cell 150 is substantially identical in configuration to the cylindrical battery cell 140 of FIG. 17, except that the uncoated portion 146a of the first electrode plate employs the electrode plate structure of the second embodiment (variant form).

[0319] 18, the uncoated portion 146a of the first electrode plate may have a shape in which the height of the outer uncoated portion B3 gradually or stepwise decreases toward the inner circumferential surface of the battery can 142. Preferably, an imaginary line connecting the uppermost ends of the outer uncoated portions B3 may have the same or similar shape as the inner circumferential surface of the beading portion 147.

[0320] The outer uncoated portion B3 has an inclined surface, which prevents the outer uncoated portion B3 from being damaged by the beading portion 147 when the battery can 142 is pressed in to form the beading portion 147. This also prevents the outer uncoated portion B3 from coming into contact with the battery can 142 of the opposite polarity, which could cause an internal short circuit.

[0321] Other configurations of the cylindrical battery cell 150 are substantially the same as those of the above-described embodiment (variant).

[0322] The uncoated portions 146a and 146b are not limited to the structure shown in the drawings. Therefore, the uncoated portions 146a and 146b may selectively have the structure of the uncoated portions of the electrode plates according to the embodiment (variant) as well as the structure of the conventional uncoated portions.

[0323] FIG. 19 is a cross-sectional view of a cylindrical battery cell 160 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0324] Referring to FIG. 19, the cylindrical battery cell 160 is substantially identical in configuration to the cylindrical battery cells 140 and 150 described above, except that the lead 149 connected to the first current collector 144 is directly connected to the cap plate 143a of the sealing body 143 through the lead hole 151 of the insulator 146, and the insulator 146 and the first current collector 144 are in close contact with the lower surface of the cap plate 143a.

[0325] In the cylindrical battery cell 160, the diameter of the first current collector 144 and the outermost diameter of the middle uncoated portion B2 are smaller than the smallest inner diameter of the battery can 142. In addition, the diameter of the first current collector 144 may be the same as or larger than the outermost diameter of the middle uncoated portion B2.

[0326] Specifically, the minimum inner diameter of the battery can 142 may correspond to the inner diameter of the battery can 142 at the position where the beading portion 147 is formed. In this case, the outermost diameters of the first current collector 144 and the middle uncoated portion B2 are smaller than the inner diameter of the battery can 142 at the position where the beading portion 147 is formed. In addition, the diameter of the first current collector 144 may be the same as or larger than the outermost diameter of the middle uncoated portion B2. The peripheral region of the insulator 146 may be folded downward and interposed between the outer uncoated portion B3 and the beading portion 147 to fix the combination of the electrode assembly 141 and the first current collector 144.

[0327] Preferably, the insulator 146 includes a portion covering the outer uncoated portion B3 and a portion covering the first current collecting plate 144, and the portion connecting these two portions may be curved together to correspond to the curved shape of the beading portion 147. The insulator 146 may insulate the outer uncoated portion B3 from the inner circumferential surface of the beading portion 147, and may also insulate the first current collecting plate 144 from the inner circumferential surface of the beading portion 147.

[0328] The first current collector 144 may be positioned higher than the lower end of the beading portion 147 and may be bonded to the core-side uncoated portion B1 and the middle uncoated portion B2. In this case, the pressing depth D1 of the beading portion 147 is equal to or smaller than the distance D2 from the inner circumferential surface of the battery can 142 to the boundary between the outer-side uncoated portion B3 and the middle uncoated portion B2. Therefore, the core-side uncoated portion B1, the middle uncoated portion B2, and the first current collector 144 bonded thereto may be positioned higher than the lower end of the beading portion 147. The lower end of the beading portion 147 refers to a notched valley portion located between the beading portion 147 and the portion of the battery can 142 that houses the electrode assembly 141.

[0329] Because the core-side uncoated portion B1 and the middle uncoated portion B2 occupy the radially inner space of the beading portion 147, the empty space between the electrode assembly 141 and the cap plate 143a is minimized. In addition, the connecting plate 143c, which was previously located in the empty space between the electrode assembly 141 and the cap plate 143a, is omitted. Therefore, the lead 149 of the first current collector 144 can be directly connected to the underside of the cap plate 143a. This structure reduces the empty space within the battery cell, allowing the energy density to be maximized by the reduced empty space.

[0330] In the cylindrical battery cell 160, the first current collector plate 144 and the second current collector plate 145 may be welded to the ends of the uncoated portions 146a and 146b, respectively, similar to the above-described embodiments.

[0331] The uncoated portions 146a and 146b are not limited to the illustrated structure, and may selectively have the structure of an uncoated portion of an electrode plate according to an embodiment (variant) as well as the structure of a conventional uncoated portion.

[0332] FIG. 20 is a cross-sectional view of a cylindrical battery cell 170 according to yet another embodiment of the present invention taken along the Y axis.

[0333] Referring to FIG. 20, the cylindrical battery cell 170 differs from the cylindrical battery cell 140 shown in FIG. 17 in that the structure of the electrode assembly is substantially the same, but other structures except for the electrode assembly have been changed.

[0334] Specifically, the cylindrical battery cell 170 includes a battery can 171 having a rivet terminal 172 inserted therethrough. The rivet terminal 172 is attached to the closed surface (top surface in the drawing) of the battery can 171. The rivet terminal 172 is riveted into a through-hole in the battery can 171 with a second insulating gasket 173 interposed therebetween. The rivet terminal 172 is exposed to the outside in the direction opposite to the direction of gravity.

[0335] The rivet terminal 172 includes a terminal exposure portion 172a and a terminal insertion portion 172b. The terminal exposure portion 172a is exposed to the outside of the closed surface of the battery can 171. The terminal exposure portion 172a may be located approximately at the center of the closed surface of the battery can 171. The maximum diameter of the terminal exposure portion 172a may be larger than the maximum diameter of the through-hole formed in the battery can 171. The terminal insertion portion 172b may penetrate approximately the center of the closed surface of the battery can 171 to be electrically connected to the uncoated portion 146a of the first electrode plate. The terminal insertion portion 172b may be rivet-connected to the inner surface of the battery can 171. That is, an end of the terminal insertion portion 172b may be bent toward the inner surface of the battery can 171. The maximum diameter of the end of the terminal insertion portion 172b may be larger than the maximum diameter of the through-hole in the battery can 171.

[0336] The lower end surface of the terminal insertion portion 172b may be welded to the first current collecting plate 144 connected to the uncoated portion 146a of the first electrode plate. An insulating cap 174 made of an insulating material may be interposed between the first current collecting plate 144 and the inner surface of the battery can 171. The insulating cap 174 covers the upper portion of the first current collecting plate 144 and the upper peripheral edge of the electrode assembly 141. This prevents the outer uncoated portion B3 of the electrode assembly 141 from coming into contact with the inner surface of the battery can 171, which has the opposite polarity, and causing a short circuit. The terminal insertion portion 172b of the rivet terminal 172 may penetrate the insulating cap 174 and be welded to the first current collecting plate 144.

[0337] The second gasket 173 is interposed between the battery can 171 and the rivet terminal 172 to prevent electrical contact between the battery can 171 and the rivet terminal 172, which have opposite polarities. This allows the upper surface of the battery can 171, which has a substantially flat shape, to function as a second electrode terminal of the cylindrical battery cell 170.

[0338] The second gasket 173 includes a gasket exposing portion 173a and a gasket inserting portion 173b. The gasket exposing portion 173a is interposed between the terminal exposing portion 172a of the rivet terminal 172 and the battery can 171. The gasket inserting portion 173b is interposed between the terminal inserting portion 172b of the rivet terminal 172 and the battery can 171. The gasket inserting portion 173b may be deformed when the terminal inserting portion 172b is riveted, and may be tightly attached to the inner surface of the battery can 171. The second gasket 173 may be made of, for example, an insulating polymer resin.

[0339] The gasket exposing portion 173a of the second gasket 173 may extend to cover the outer peripheral surface of the terminal exposing portion 172a of the rivet terminal 172. When the second gasket 173 covers the outer peripheral surface of the rivet terminal 172, it is possible to prevent a short circuit from occurring during the process of connecting an electrical connection part, such as a bus bar, to the upper surface of the battery can 171 and / or the rivet terminal 172. Although not shown, the gasket exposing portion 173a may extend to cover not only the outer peripheral surface of the terminal exposing portion 172a but also a portion of the upper surface.

[0340] When the second gasket 173 is made of a polymer resin, the second gasket 173 may be joined to the battery can 171 and the rivet terminal 172 by heat sealing. In this case, the airtightness at the joining interface between the second gasket 173 and the rivet terminal 172 and at the joining interface between the second gasket 173 and the battery can 171 is strengthened. Meanwhile, when the gasket exposed portion 173a of the second gasket 173 has a shape that extends to the upper surface of the terminal exposed portion 172a, the rivet terminal 172 may be joined integrally with the second gasket 173 by insert injection.

[0341] The remaining area 175 on the top surface of the battery can 171 excluding the area occupied by the rivet terminal 172 and the second gasket 173 corresponds to a second electrode terminal having a polarity opposite to that of the rivet terminal 172 .

[0342] The second current collecting plate 176 is coupled to the lower part of the electrode assembly 141. The second current collecting plate 176 is made of a conductive metal material such as aluminum, steel, copper, or nickel, and is electrically connected to the uncoated portion 146b of the second electrode plate.

[0343] Preferably, the second current collector 176 is electrically connected to the battery can 171. Therefore, the second current collector 176 may be fixed with at least a portion of its peripheral edge interposed between the inner surface of the battery can 171 and the first gasket 178b. In one example, at least a portion of the peripheral edge of the second current collector 176 may be fixed to the beading portion 180 by welding while being supported on the lower end surface of the beading portion 180 formed at the lower end of the battery can 171. In a modified embodiment, at least a portion of the peripheral edge of the second current collector 176 may be directly welded to the inner wall surface of the battery can 171.

[0344] The second current collecting plate 176 may have a plurality of projections and recesses (not shown) formed radially on the surface facing the non-coated portion 146b. When the projections and recesses are formed, the second current collecting plate 176 may be pressed against the projections and recesses to press the non-coated portion 146b into the projections and recesses.

[0345] Preferably, the second current collector plate 176 and the end of the non-coating portion 146b can be joined by welding, for example, laser welding.

[0346] The sealing body 178 that seals the lower open end of the battery can 171 includes a cap plate 178a and a first gasket 178b. The first gasket 178b electrically isolates the cap plate 178a from the battery can 171. A crimping portion 181 secures the periphery of the cap plate 178a and the first gasket 178b together. The cap plate 178a is provided with a vent portion 179. The configuration of the vent portion 179 is substantially the same as in the above-described embodiment (variant).

[0347] Preferably, the cap plate 178a is made of a conductive metal material. However, the cap plate 178a does not have electrical polarity because the first gasket 178b is interposed between the cap plate 178a and the battery can 171. The seal 178 seals the open end of the lower part of the battery can 171 and functions to release gas when the internal pressure of the battery cell 170 increases above a critical value.

[0348] Preferably, the rivet terminal 172 electrically connected to the uncoated portion 146a of the first electrode plate is used as the first electrode terminal. Furthermore, a portion 175 of the upper surface of the battery can 171, excluding the rivet terminal 172, electrically connected to the uncoated portion 146b of the second electrode plate via the second current collector plate 176 is used as a second electrode terminal having the opposite polarity to the first electrode terminal. When two electrode terminals are located on the upper portion of the cylindrical battery cell 170, electrical connection components such as bus bars can be disposed on only one side of the cylindrical battery cell 170. This can simplify the battery pack structure and improve energy density. Furthermore, the portion 175 used as the second electrode terminal has a substantially flat shape, ensuring a sufficient bonding area when bonding electrical connection components such as bus bars. This allows the cylindrical battery cell 170 to reduce resistance at the bonding locations of the electrical connection components to a desirable level.

[0349] Meanwhile, the structure of the electrode assembly 141 and the structure of the uncoated portion are not limited to those shown in the drawings, and may be replaced with the structures of the above-described embodiments (variations).

[0350] FIG. 21 is a cross-sectional view of a cylindrical battery cell 180 according to yet another embodiment of the present invention taken along the Y axis.

[0351] Referring to FIG. 21, the cylindrical battery cell 180 has substantially the same structure as the cylindrical battery cell 150 shown in FIG. 18 in terms of the electrode assembly 141, and other configurations except for the electrode assembly 141 are substantially the same as the cylindrical battery cell 170 shown in FIG. 20.

[0352] Therefore, the configurations of the embodiments (variations) of the cylindrical battery cells 150 and 170 can be similarly applied to the cylindrical battery cell 180.

[0353] Furthermore, the structure of the electrode assembly 141 and the structure of the uncoated portion are not limited to those shown in the drawings, and may be replaced with the structures of the above-described embodiments (variations).

[0354] FIG. 22 is a cross-sectional view of a cylindrical battery cell 190 according to yet another embodiment of the present invention taken along the Y axis.

[0355] Referring to FIG. 22, a cylindrical battery cell 190 includes the electrode assembly 110 shown in FIG. 14, and other configurations except for the electrode assembly 110 are substantially identical to the cylindrical battery cell 140 shown in FIG.

[0356] 22, uncoated portions 146a and 146b of electrode assembly 110 are bent from the outer periphery toward the core. At this time, core-side uncoated portion B1 is not substantially bent because it is lower than the other portions. A first current collecting plate 144 may be welded to the bent surface of uncoated portion 146a, and a second current collecting plate 145 may be welded to the bent surface of uncoated portion 146b. The bent surfaces may be formed at the top and bottom of electrode assembly 110, respectively, as the uncoated portions 146a and 146b are folded, overlapping each other in multiple layers.

[0357] The height of the core-side uncoated region B1 is relatively lower than the other regions of the electrode assembly 110. Also, as shown in Figure 14, the height H of the innermost uncoated region of the intermediate uncoated region B2 is equal to or shorter than the radial length R of the core-side uncoated region B1.

[0358] Therefore, even if the non-coating portion 146a is bent toward the core side, the cavity 112 of the core of the electrode assembly 110 is not closed and can be open at the top.

[0359] If cavity 112 is not blocked, the electrolyte injection process is not hindered, improving the efficiency of the electrolyte injection. Also, a welding jig can be inserted through cavity 112 to easily weld second current collector plate 145 and battery can 142 together.

[0360] When the plain portions 146a, 146b have a divided structure, if the width and / or height and / or spacing pitch of the divided pieces are adjusted to satisfy the numerical range of the above-mentioned embodiment, when the divided pieces are bent, the divided pieces are overlapped in multiple layers to an extent that sufficient welding strength can be ensured, and no open spaces (gaps) are formed on the bent surface.

[0361] The structure of the uncoated portions 146a, 146b may be modified without limitation to the structure according to the above-described embodiment (variant), and there is no restriction on applying a conventional uncoated portion structure to either one of the uncoated portions 146a, 146b.

[0362] FIG. 23 is a cross-sectional view of a cylindrical battery cell 200 according to yet another embodiment of the present invention taken along the Y axis.

[0363] Referring to FIG. 23, a cylindrical battery cell 200 includes the electrode assembly 110 shown in FIG. 14, and other configurations except for the electrode assembly 110 are substantially identical to the cylindrical battery cell 180 shown in FIG. 21.

[0364] 23, the uncoated portions 146a and 146b of the electrode assembly 110 are bent from the outer periphery toward the core. At this time, the core-side uncoated portion B1 is not substantially bent because its height is lower than the other portions. The first current collector 144 may be welded to the bent surface of the uncoated portion 146a, and the second current collector 176 may be welded to the bent surface of the uncoated portion 146b.

[0365] The height of the core-side uncoated region B1 is relatively lower than the other regions of the electrode assembly 110. Also, as shown in Figure 14, the height H of the innermost uncoated region of the intermediate uncoated region B2 is equal to or shorter than the radial length R of the core-side uncoated region B1.

[0366] Therefore, even if the uncoated portions 146a and 146b are bent toward the core side, the cavity 112 of the core of the electrode assembly 110 is not closed and can be open at the top.

[0367] If cavity 112 is not blocked, the electrolyte injection process is not hindered, improving the efficiency of the electrolyte injection. Also, a welding jig can be inserted through cavity 112 to easily weld second current collector plate 176 and battery can 171 together.

[0368] When the plain portions 146a, 146b have a divided structure, if the width and / or height and / or spacing pitch of the divided pieces are adjusted to satisfy the numerical range of the above-mentioned embodiment, when the divided pieces are bent, the divided pieces are overlapped in multiple layers to an extent that sufficient welding strength can be ensured, and no open spaces (gaps) are formed on the bent surface.

[0369] The structure of the uncoated portions 146a, 146b may be modified without limitation to the structure according to the above-described embodiment (variant), and there is no restriction on applying a conventional uncoated portion structure to either one of the uncoated portions 146a, 146b.

[0370] FIG. 24 is a cross-sectional view of a cylindrical battery cell 210 according to yet another embodiment of the present invention taken along the Y axis.

[0371] Referring to FIG. 24, a cylindrical battery cell 210 includes the electrode assembly 100 shown in FIG. 13, and other configurations except for the electrode assembly 100 are substantially identical to the cylindrical battery cell 140 shown in FIG. 17.

[0372] Preferably, the uncoated portions 146a and 146b of the electrode assembly 100 are bent from the outer periphery toward the core. At this time, the core-side uncoated portion B1 and the outer periphery-side uncoated portion B3 of the uncoated portion 146a are not substantially bent because they are lower in height than the other portions. The same applies to the uncoated portion 146b. The first current collecting plate 144 may be welded to the bent surface of the uncoated portion 146a, and the second current collecting plate 145 may be welded to the bent surface of the uncoated portion 146b.

[0373] The height of the core-side uncoated region B1 is relatively lower than that of the intermediate uncoated region B2. Also, as shown in Figure 14, the height H of the innermost uncoated region in the intermediate uncoated region B2 is equal to or shorter than the radial length R of the core-side uncoated region B1.

[0374] Therefore, even if the uncoated portions 146a and 146b are bent toward the core side, the cavity 102 of the core of the electrode assembly 100 is not closed and can be open at the top.

[0375] If cavity 102 is not blocked, the electrolyte injection process is not hindered, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the cavity to easily perform the welding process between second current collector plate 145 and battery can 142.

[0376] In addition, the height of outer uncoated portion B3 is relatively lower than that of intermediate uncoated portion B2. Therefore, when uncoated portion 146a is bent, outer uncoated portion B3 is not substantially bent. In addition, outer uncoated portion B3 is sufficiently spaced apart from beading portion 147, which solves the problem of outer uncoated portion B3 being damaged when beading portion 147 is pressed in.

[0377] When the plain portions 146a, 146b have a divided structure, if the width and / or height and / or spacing pitch of the divided pieces are adjusted to satisfy the numerical range of the above-mentioned embodiment, when the divided pieces are bent, the divided pieces are overlapped in multiple layers to an extent that sufficient welding strength can be ensured, and no open spaces (gaps) are formed on the bent surface.

[0378] The structure of the uncoated portions 146a, 146b may be modified without limitation to the structure according to the above-described embodiment (variant), and there is no restriction on applying a conventional uncoated portion structure to either one of the uncoated portions 146a, 146b.

[0379] FIG. 25 is a cross-sectional view of a cylindrical battery cell 220 according to yet another embodiment of the present invention taken along the Y axis.

[0380] Referring to FIG. 25, a cylindrical battery cell 220 includes the electrode assembly 100 shown in FIG. 13, and other configurations except for the electrode assembly 100 are substantially the same as the cylindrical battery cell 180 shown in FIG.

[0381] Preferably, the uncoated portions 146a and 146b of the electrode assembly 100 are bent from the outer periphery toward the core. At this time, the core-side uncoated portion B1 of the uncoated portion 146a is not substantially bent because its height is lower than the other portions. The same applies to the uncoated portion 146b. The first current collector 144 may be welded to the bent surface of the uncoated portion 146a, and the second current collector 176 may be welded to the bent surface of the uncoated portion 146b.

[0382] In the electrode assembly 100, the height of the core-side uncoated region B1 is relatively lower than that of the intermediate uncoated region B2. Also, as shown in Fig. 14, the height H of the innermost uncoated region in the intermediate uncoated region B2 is equal to or shorter than the radial length R of the core-side uncoated region B1.

[0383] Therefore, even if the uncoated portion 146a is bent toward the core side, the cavity 102 of the core of the electrode assembly 100 is not closed and can be open at the top.

[0384] If cavity 102 is not blocked, the electrolyte injection process is not hindered, improving the efficiency of the electrolyte injection. Also, a welding jig can be inserted through cavity 102 to easily perform the welding process between second current collector plate 176 and battery can 171.

[0385] Furthermore, the height of outer uncoated portion B3 of uncoated portion 146a is relatively smaller than that of intermediate uncoated portion B2. Therefore, when uncoated portion 146a is folded, outer uncoated portion B3 is not substantially folded. The same is true for uncoated portion 146b.

[0386] When the plain portions 146a, 146b have a divided structure, if the width and / or height and / or spacing pitch of the divided pieces are adjusted to satisfy the numerical range of the above-mentioned embodiment, when the divided pieces are bent, the divided pieces are overlapped in multiple layers to an extent that sufficient welding strength can be ensured, and no open spaces (gaps) are formed on the bent surface.

[0387] The structure of the uncoated portions 146a, 146b may be modified without limitation to the structure according to the above-described embodiment (variant), and there is no restriction on applying a conventional uncoated portion structure to either one of the uncoated portions 146a, 146b.

[0388] The cylindrical battery cells according to the above-described embodiments (variations) can be used to manufacture battery packs.

[0389] FIG. 26 is a diagram schematically illustrating the configuration of a battery pack according to one embodiment of the present invention.

[0390] 26, a battery pack 300 according to one embodiment of the present invention includes an assembly of electrically connected cylindrical battery cells 301 and a pack housing 302 that accommodates the assembly. The cylindrical battery cells 301 may be any one of the battery cells according to the above-described embodiments (variants). For convenience of illustration, components such as bus bars for electrically connecting the cylindrical battery cells 301, a cooling unit, and external terminals are not shown.

[0391] The battery pack 300 may be installed in a vehicle, which may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle, including a four-wheeled vehicle or a two-wheeled vehicle.

[0392] FIG. 27 is a diagram illustrating a vehicle including the battery pack 300 of FIG.

[0393] 27, an automobile V according to an embodiment of the present invention includes a battery pack 300 according to an embodiment of the present invention. The automobile V operates by receiving a supply of power from the battery pack 300 according to an embodiment of the present invention.

[0394] According to one embodiment of the present invention, the uncoated portions protruding from the upper and lower sides of the electrode assembly themselves are used as electrode tabs, thereby reducing the internal resistance of a cylindrical battery cell and increasing the energy density.

[0395] According to another embodiment of the present invention, by improving the structure of the uncoated portion of the electrode assembly, interference between the electrode assembly and the inner surface of the battery can does not occur during the process of forming the beading portion of the battery can, thereby preventing an internal short circuit in a cylindrical battery cell due to partial deformation of the electrode assembly.

[0396] According to yet another embodiment of the present invention, the structure of the uncoated portion of the electrode assembly is improved to prevent the uncoated portion from tearing near the notch valley when the uncoated portion is bent, and the number of overlapping layers of the uncoated portion is sufficiently increased to improve weld strength.

[0397] According to yet another embodiment of the present invention, the structure of the uncoated portion adjacent to the core of the electrode assembly is improved to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent, thereby facilitating the electrolyte injection process and the welding process of the battery can and the current collector plate.

[0398] According to yet another embodiment of the present invention, it is possible to provide a cylindrical battery cell having a structure in which internal resistance is low, internal short circuits are prevented, and welding strength between a current collector plate and an uncoated portion is improved, as well as a battery pack and a vehicle including the same.

[0399] As described above, the present invention has been described using limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying 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. [Example]

[0400] (1) Preparation of the current collector 1) Preparation of the positive electrode current collector As shown in Table 1 below, a metal thin film (thickness 15 μm) for a current collector made of aluminum material including a plain area on which the pieces of Group 1 and Group 2 were to be formed was prepared.

[0401] The metal thin film had a length in the winding direction (B1 + B2 + B3) of 4,000 mm from the core to the outer periphery, and a width in the winding axial direction of 75 mm. The metal thin film was divided into regions: B1 was the core-side uncoated region, B3 was the outer-periphery uncoated region, and B2, located between the core-side uncoated region and the outer-periphery uncoated region, was an intermediate uncoated region. The length of B1 was 350 mm, the length of B2 was 3,500 mm, and the length of B3 was 150 mm.

[0402] In the width direction of the metal thin film, a predetermined width from the second side portion inward is made up of the positive electrode active material portion, and the remainder is made up of the first portion which is an uncoated portion, and the height of the core side uncoated portion and the outer periphery side uncoated portion in the winding axis direction is lower than that of the intermediate uncoated portion.

[0403] 2) Preparation of negative electrode current collector A negative electrode current collector was prepared in the same manner as the positive electrode current collector, except that a copper thin film (thickness 10 μm) was used as the current collector material and the width in the winding axis direction was 80 mm.

[0404] [Table 1]

[0405] (2) Manufacturing of the negative electrode Average particle size (D 50) 11 μm amorphous natural graphite, carbon black, carboxymethyl cellulose (CMC), and styrene butadiene rubber (SBR) were mixed with water in a weight ratio of 94:1.5:2:2.5 to prepare a slurry for the negative electrode active material portion, with the remaining components (excluding water) being 50 wt%. The slurry was applied to the negative electrode active material portion on the surface of the copper current collector prepared as described above using a slot die at a running speed of 40 m / min. The width of the negative electrode active material portion in the winding direction was 70 mm, and the width of the uncoated portion was 10 mm. The loading amount of the negative electrode active material was 16 mg / cm based on the electrode area. 2 The copper thin film coated with the negative electrode active material slurry was dried by passing it through a 60 m long hot air oven, and the oven temperature was controlled to maintain 130°C. Then, the target thickness was set to 180 μm and roll pressed to obtain a negative electrode with a density of 3.45 g / cc.

[0406] Thereafter, the middle plain section was notched with a laser to divide it into a plurality of pieces so as to satisfy the conditions in Table 1. At this time, the lower ends of the notch valleys of each piece were adjusted to have substantially the same height.

[0407] (3) Manufacturing of the positive electrode Li(Ni) as the positive electrode active material 0.6 Mn 0.2 Co 0.2 A slurry for the positive electrode active material part was prepared by adding 02 (NCM-622), carbon black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder to water as a dispersion medium in a weight ratio of 96:2:2. The slurry was coated on the surface of the aluminum current collector prepared as described above, and the cathode was fabricated by drying and rolling under the same conditions as for the negative electrode. The width of the positive electrode active material part in the winding direction was 65 mm, and the width of the uncoated area was 10 mm.

[0408] At this time, the positive electrode active material part was set to an NP ratio of 1.18 (118%, approximately 27.7 cm ) of the battery, taking into account the theoretical discharge capacity of the NMC622. 2 ) was adjusted.

[0409] Thereafter, the middle plain section was notched with a laser to divide it into a plurality of pieces so as to satisfy the conditions in Table 1. At this time, the lower ends of the notch valleys of each piece were adjusted to have substantially the same height.

[0410] (4) Separation membrane manufacturing Approximately 5 wt% of polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP) polymer was added to tetrahydrofuran (THF) and dissolved at 50°C for approximately 12 hours to prepare a polymer solution. BaTiO powder with a particle size of approximately 400 nm was added and dispersed in the polymer solution at 20 wt% of the total solids to prepare a mixed solution (BaTiO / PVdF-HFP = 80:20 (weight ratio)). The mixed solution was coated on both sides of a porous polypropylene film using a doctor blade. After coating, the THF was dried to obtain the final organic / inorganic composite porous separator. The final separator thickness was approximately 30 μm. Measurement of the pores using a porosimeter revealed that the pore size and porosity of the final organic / inorganic composite porous separator were 0.4 μm and 60%, respectively.

[0411] (5) Preparation of electrode assembly The prepared negative electrode, separator, and positive electrode were stacked in this order and wound up to fabricate an electrode assembly with a jelly roll structure. In the example, the stacking was performed in the structure shown in FIG. 9a, while in the comparative example, the stacking was performed in the structure shown in FIG. 8. In the example, L1 was 2.5 mm, and L2 was 1.5 mm. In the comparative example, the positive electrode, negative electrode, and separator were arranged so that the surfaces of the negative electrode active material portion and the positive electrode active material portion were covered with the separator. Meanwhile, as shown in FIG. 29, it was confirmed that the lengths from both the upper and lower ends of the electrode assembly to the end of the separator were approximately 1.0 mm and 1.5 mm, respectively.

[0412] (6) Battery manufacturing (4680 type) The exposed upper and lower sections of Groups 1 to 7 of the electrode assembly were folded toward the core, and then positive and negative current collectors were welded to the upper and lower bent surfaces, respectively. A cylindrical cell with the structure shown in FIG. 25 was then fabricated. Specifically, the electrode assembly with the welded positive and negative current collectors was inserted into a battery housing with pre-attached external terminals. The positive and negative current collectors were welded to the external terminals, and the periphery of the negative current collector was welded to the beading. The battery housing was then placed in the chamber of an electrolyte injection device and stood upright so that the opening of the battery housing was facing away from gravity. A non-aqueous electrolyte was then prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent mixture of ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) in a 1:2:1 (volume ratio). Then, an electrolyte was injected from the opening of the battery housing, and the chamber pressure was increased to 800 kPa for 20 seconds and maintained for 150 seconds. After that, the chamber pressure was reduced to -90 kPa for 20 seconds and a substantial vacuum state was maintained for 20 seconds. After the electrolyte impregnation process was completed, the opening of the battery housing was sealed with a sealant via a gasket, completing the fabrication of a cylindrical cell.

[0413] The comparative battery was also fabricated by applying substantially the same manufacturing process as described above.

[0414] (7) Evaluation of electrolyte impregnation The batteries of the example and comparative example were disassembled to obtain the positive and negative electrodes. Then, a total of nine 10 cm diameter holes were cut into the negative and positive electrodes. 2100 samples were cut out. The nine samples were obtained by cutting out the nine samples from the area adjacent to the core of the electrode assembly when the electrode was unfolded: three (#1 to #3) from the area adjacent to the outer periphery of the electrode assembly, three (#7 to #9) from the area adjacent to the outer periphery of the electrode assembly, and three (#4 to #6) from the central area of ​​the electrode in the winding direction. When three samples were obtained from each sample acquisition area, one was taken from the bottom, one from the center, and one from the top of the active material layer along the winding axis. Referring to Figure 30, #1, #4, and #7 were taken near one end of the electrode width direction, #3, #6, and #9 were taken near the other end of the electrode width direction, and #2, #5, and #8 were taken from the middle portion. Note that Figure 30 simply shows the sample acquisition areas based on Figure 9a. For other shapes and values ​​of the sample acquisition areas, refer to Table 1 above.

[0415] The amount of impregnated electrolyte was determined by measuring the weight of the sample impregnated with the electrolyte, washing each sample with DMC (dimethyl carbonate), drying at 150°C, measuring the weight of the dried sample, and then calculating the difference between the weights before and after.

[0416] In the positive electrode of the example, the average amount of electrolyte impregnated in each of the #1 to #9 sections was 21.7 mg, while in the comparative example it was 20.7 mg. In the negative electrode of the example, the average amount of electrolyte impregnated in each of the #1 to #9 sections was 35.6 mg, while in the comparative example it was 33.2 mg.

[0417] This confirms that the electrode assemblies of the examples having the structural features of the present invention exhibit superior electrolyte impregnation properties compared to the comparative examples.

[0418] [Table 2]

[0419] (8) Capacity retention rate evaluation The capacity retention rate was evaluated using the batteries manufactured in the examples and comparative examples. To measure the life characteristics and capacity retention rate of each battery, a constant current charge of 1.0 C up to 4.25 V and a constant current discharge down to 2.5 V were performed from the first cycle to the 100th cycle. In the present invention, the capacity retention rate can be defined by the following [Equation 1]. [Number 1] Capacity retention rate (%) = [100th cycle discharge capacity / 1st cycle discharge capacity] x 100

[0420] 28 is a graph comparing the battery capacities of the batteries of the examples and comparative examples. Referring to this graph, the battery according to an embodiment of the present invention exhibits superior electrochemical properties compared to a battery having conventional structural characteristics, such as the comparative example. In FIG. 28, the solid line represents the battery of the example, and the dotted line represents the battery of the comparative example. This confirms that the battery according to an embodiment of the present invention does not exhibit a decrease in electrochemical performance compared to the prior art, and furthermore, is advantageous in terms of improved stability due to less damage to the separator during electrode assembly fabrication. [Explanation of symbols]

[0421] 10 First electrode plate 10a Plain area 10a Positive electrode uncoated area 11 Second electrode plate 11a Negative electrode uncoated area 11a Plain area 12 Separation membrane 20 Current collector 21 Active material 22 Plain area 30 Current collector plate 31 Current collector plate 32 Plain area 33 Cavity 34 Upper marginal area 35 Width Contrast 40 Electrode plate 41 Current collector 42 Electrode active material section 43 Plain area 43a Upper plain part 43b Lower plain part 44 insulating coating layer 45 Electrode plate 50 electrode plate 60 Electrode plate 61-minute sections 61' section 70 Electrode plate 80 Electrode assembly 81 End 90 Electrode assembly 91 End 100 electrode assembly 101 End 102 Cavity 110 Electrode assembly 111 End 112 Cavity 120 Electrode assembly 121 End 122 Cavity 130 Electrode assembly 131 End 132 Cavity 140 cylindrical battery cells 140 battery cells 141 Electrode assembly 142 Battery Can 143 Sealed body 143a Cap Plate 143b First gasket 143c connecting plate 143d Protrusion 144 First current collector plate 145 Second current collector plate 146 Insulators 146a Plain area 146b Plain area 147 Beading section 148 Crimping section 149 leads 150 cylindrical battery cells 151 Lead hole 152 Venting section 160 cylindrical battery cells 170 cylindrical battery cells 171 Battery Can 172 Rivet terminal 172a Exposed terminal part 172b Terminal insertion part 173 Second gasket 173a Exposed gasket 173b Gasket insert 174 Insulating Cap 175 areas 176 Second current collector plate 178 Sealed body 178a Cap Plate 178b First gasket 179 Vent 180 cylindrical battery cells 180 Beading section 181 Crimping section 190 cylindrical battery cells 200 cylindrical battery cells 210 cylindrical battery cells 220 cylindrical battery cells 300 battery pack 301 Cylindrical Battery Cell 302 Pack Housing

Claims

1. An electrode assembly including a first electrode plate, a second electrode plate, and a separator interposed between the first electrode plate and the second electrode plate, The first electrode plate is a positive electrode plate and the second electrode plate is a negative electrode plate, or the first electrode plate is a negative electrode plate and the second electrode plate is a positive electrode plate; the first electrode plate, the second electrode plate, and the separator are each independently strip-shaped with an aspect ratio of more than 1, and the first electrode plate, the second electrode plate, and the separator are stacked with their longitudinal directions parallel to each other; The first electrode plate, the second electrode plate, and the separator each independently have a first side portion that is a first end in a width direction, and a second side portion that is a second end at a position opposite to the first side portion, the first electrode plate and the second electrode plate include a first portion and a second portion on at least one side, the first portion being an electrode active material portion coated with an electrode active material and extending from the second side toward the first side, and the second portion being a plain portion not coated with an electrode active material and extending from the first side toward the second side to the electrode active material portion, In the electrode assembly, the first side of the first electrode plate and the first side of the second electrode plate are arranged to face in opposite directions, In the electrode assembly, the first side of the separator protrudes outward from the second side of the first electrode plate and is disposed on the electrode active material portion of the second electrode plate, and the second side of the separator protrudes outward from the second side of the second electrode plate and is disposed on the uncoated portion of the first electrode plate.

2. 2. The electrode assembly of claim 1, wherein the first electrode plate is a positive electrode plate and the second electrode plate is a negative electrode plate.

3. 2. The electrode assembly according to claim 1, wherein, based on the width direction, a width of the electrode active material portion of the first electrode plate is narrower than a width of the electrode active material portion of the second electrode plate, and both ends of the electrode active material portion of the first electrode plate in the width direction are disposed between both ends of the electrode active material portion of the second electrode plate in the width direction.

4. 4. The electrode assembly according to claim 1, wherein at least one of the first electrode plate and the second electrode plate has an uncoated portion, at least a portion of which is divided into a plurality of segments by incision grooves of a predetermined depth.

5. The electrode assembly of claim 4 , wherein each of the plurality of segments has a rectangular, trapezoidal, triangular, parallelogram, semicircular, or semi-elliptical configuration.

6. the first electrode plate has the divided piece of the first electrode plate, The electrode assembly according to claim 5 , wherein the separation film is disposed so as to cover a notched valley of the cut groove of the segment.

7. The electrode assembly of claim 1 , wherein the first electrode plate, the second electrode plate, and the separator are wound around an axis in a longitudinal direction to form a plurality of winding turns.

8. the electrode assembly has a plurality of winding turns in which the first electrode plate, the second electrode plate, and the separator are wound around an axis in a longitudinal direction; The electrode assembly according to claim 6 , wherein all or at least some of the plurality of segments are bent in a radial direction relative to the axis at a bending point that is a point within the segment.

9. The electrode assembly of claim 8 , wherein the second side of the separator is disposed on the uncoated portion of the first electrode plate and between the electrode active material portion and a bending point.

10. The electrode assembly of claim 9 , wherein the bending point and the second side of the separator are spaced apart by 0.1 mm or more.

11. At least one of the uncoated portions of the first electrode plate and the second electrode plate includes a core-side uncoated portion adjacent to a core of the electrode assembly, an outer periphery-side uncoated portion adjacent to an outer periphery of the electrode assembly, and an intermediate uncoated portion interposed between the core-side uncoated portion and the outer periphery-side uncoated portion, At least one of the core-side uncoated portion and the outer-periphery-side uncoated portion has a distance from the electrode active material portion to the first side portion that is shorter than that of the intermediate uncoated portion; The electrode assembly according to claim 1 , wherein the electrode active material portion has a constant width from a core side to an outer periphery side in a width direction.

12. At least one of the uncoated portions of the first electrode plate and the second electrode plate includes a core-side uncoated portion adjacent to a core of the electrode assembly, an outer periphery-side uncoated portion adjacent to an outer periphery of the electrode assembly, and an intermediate uncoated portion interposed between the core-side uncoated portion and the outer periphery-side uncoated portion, the core-side uncoated portion has a relatively shorter distance from the electrode active material portion to the first side portion than the intermediate uncoated portion and the outer periphery-side uncoated portion; The electrode assembly according to claim 1 , wherein the electrode active material portion has a constant width from a core side to an outer periphery side in a width direction.

13. 13. The electrode assembly according to claim 11 or 12, wherein the core-side uncoated portion includes an uncoated portion of an electrode plate portion corresponding to an innermost winding turn of the electrode assembly, and the outer-periphery-side uncoated portion includes an uncoated portion of an electrode plate portion corresponding to an outermost winding turn of the electrode assembly.

14. The electrode assembly according to claim 12 , wherein all or at least a portion of the intermediate uncoated portion is divided into a plurality of segments.

15. The electrode assembly according to claim 11 or 12, wherein the height of at least a portion of the intermediate uncoated portion increases stepwise in the winding axial direction from the core side to the outer periphery side.

16. 5. The electrode assembly according to claim 4, wherein the notched valley of each of the segments and the electrode active material portion are spaced apart by a predetermined distance.

17. The separation membrane is a porous polymer substrate; The electrode assembly of claim 1 , further comprising: a porous coating layer disposed on at least one surface of the porous polymer substrate, the porous coating layer including inorganic particles and a binder polymer.

18. The electrode assembly of claim 17 , wherein the surfaces of the inorganic particles have hydrophilic properties.

19. The electrode assembly according to claim 1; a battery can that houses the electrode assembly and is electrically connected to one of the first electrode plate and the second electrode plate to have a first polarity; a sealing body that seals the open end of the battery can; a terminal electrically connected to the other of the first electrode plate and the second electrode plate, having a surface exposed to the outside and carrying a second polarity.

20. A battery pack comprising at least one battery cell according to claim 19.

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