Electrode assembly, battery, battery pack including the same, and automobile

Abstract

The present invention discloses an electrode assembly, a battery, a battery pack including the same, and a vehicle. The first electrode of the electrode assembly includes a first active material portion coated with an active material layer along a winding direction, and a first uncoated portion that is not coated with the active material layer and is exposed outside the separator. The first uncoated portion includes a first portion adjacent to the core of the electrode assembly, a second portion adjacent to the outer peripheral surface of the electrode assembly, and a third portion between the first portion and the second portion. The third portion includes a plurality of segmented pieces spaced apart along the winding direction by a plurality of cutting grooves extending in the winding axis direction. The height of the first portion is relatively lower than the height of the uncoated portion at the lower end of the cutting groove.

Description

Technical Field

[0001] The present invention relates to an electrode assembly, a battery, a battery pack including the same, and a vehicle.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0089945 filed on July 20, 2022, and all of the content disclosed in the specification and drawings of the application is incorporated into this application.

Background Art

[0003] Secondary batteries with high applicability for each product group and having electrical characteristics such as high energy density are generally applied not only to portable devices but also to electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by an electric drive source.

[0004] Such secondary batteries have not only the primary advantage of significantly reducing the use of fossil fuels but are also environmentally friendly in that no by-products are generated by the use of energy and are attracting attention as a new energy source for improving energy efficiency.

[0005] 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 a unit secondary battery, that is, a unit battery, is about 2.5V to 4.5V. Therefore, when a higher output voltage is required, a plurality of batteries are connected in series to form a battery pack. Also, depending on the charge and discharge capacity required for the battery pack, a plurality of batteries may be connected in parallel to form a battery pack. Therefore, the number and electrical connection form of the batteries included in the battery pack can be variously set according to the required output voltage and / or charge and discharge capacity.

[0006] On the one hand, as types of unit secondary batteries, cylindrical, square, and pouch-type batteries are known. In the case of a cylindrical battery, a separator, which is an insulator, is interposed between the positive electrode and the negative electrode, and this is wound up to form a jelly-roll type electrode assembly, which is inserted into the inside of a battery housing to constitute a battery. The battery housing is called a battery can in the art. And strip-shaped electrode tabs are connected to the plain portions of the positive electrode and the negative electrode respectively, and the electrode tabs electrically connect between the electrode assembly and the electrode terminals exposed outside. For reference, the positive electrode terminal is the cap of a sealing body that seals the opening of the battery housing, and the negative electrode terminal is the battery housing. However, according to the conventional cylindrical battery having such a structure, since current is concentrated on the strip-shaped electrode tabs coupled to the positive electrode plain portion and / or the negative electrode plain portion, there is a problem that the resistance is large, heat generation is much, and the current collection efficiency is not good.

[0007] In the case of a small cylindrical battery having a form factor of 1865 (diameter: 18 mm, height: 65 mm) or 2170 (diameter: 21 mm, height: 70 mm), resistance and heat generation are not much of a problem. However, when increasing the form factor for applying the cylindrical battery to an electric vehicle, there may occur a problem that the cylindrical battery catches fire while a large amount of heat is generated around the electrode tabs during the rapid charging process.

[0008] To solve such a problem, a cylindrical battery (so-called tab-less cylindrical battery) having a structure in which the positive electrode plain portion and the negative electrode plain portion are respectively located at the upper end and the lower end of the jelly-roll type electrode assembly, and a current collector is welded to such a plain portion to improve the current collection efficiency has been presented.

[0009] FIGS. 1 to 3 are diagrams showing the manufacturing process of the tab-less cylindrical battery. FIG. 1 shows the structure of the electrode, FIG. 2 shows the winding process of the electrode, and FIG. 3 shows the process in which the current collector is welded to the bent surface area of the plain portion.

[0010] Referring to FIGS. 1 to 3, the positive electrode 10 and the negative electrode 11 have a structure in which an active material 21 is coated on a sheet-shaped current collector 20, and include a plain portion 22 on one long side along the winding direction (X-axis). The long side is a direction parallel to the X-axis direction and means the side with a relatively long length.

[0011] The electrode assembly A is manufactured by laminating the positive electrode 10 and the negative electrode 11 together with two separator membranes 12 in order as shown in FIG. 2, and then winding them in one direction (X-axis direction). At this time, the plain portion of the positive electrode 10 and the plain portion of the negative electrode 11 are arranged in opposite directions.

[0012] After the winding process, the plain portion 10a of the positive electrode 10 and the plain portion 11a of the negative electrode 11 are bent toward the core side. Then, current collectors 30 and 31 are welded and joined to the plain portions 10a and 11a, respectively.

[0013] Separate electrode tabs are not joined to the positive electrode plain portion 10a and the negative electrode plain portion 11a, and the current collectors 30 and 31 are connected to external electrode terminals, and the current path is formed with a large cross-sectional area along the winding axis direction (see arrow) of the electrode assembly A. Therefore, there is an advantage that the resistance of the battery can be reduced. This is because the resistance is inversely proportional to the cross-sectional area of the path through which the current flows.

[0014] In the tabless cylindrical battery, in order to improve the welding characteristics between the plain portions 10a and 11a and the current collectors 30 and 31, a strong pressure must be applied to the welding areas of the plain portions 10a and 11a to bend the plain portions 10a and 11a as flat as possible.

[0015] However, when bending the welding regions of the plain portions 10a and 11a, the patterns on the plain portions 10a and 11a may be deformed while being irregularly distorted. In this case, the deformed portion may come into contact with the electrode of the opposite polarity and cause an internal short circuit, or may induce fine cracks in the plain portions 10a and 11a. Also, while the plain portion 32 adjacent to the core of the electrode assembly A is being bent, all or a considerable part of the cavity 33 in the core of the electrode assembly A is blocked. Furthermore, a phenomenon may occur in which the core shape of the electrode assembly A cannot be maintained circular and collapses. In this case, problems occur in the electrolyte injection process. That is, the cavity 33 in the core of the electrode assembly A is used as a passage through which the electrolyte is injected. However, if the passage is blocked, it is difficult to inject the electrolyte. Also, in the process of inserting the electrolyte injector into the cavity 33, interference may occur between the plain portion 32 near the core, and the problem that the plain portion 32 is torn may occur.

[0016] Also, the bent portions of the plain portions 10a and 11a where the current collectors 30 and 31 are welded overlap multiple times, and there should be no empty space (gap). Thereby, sufficient welding strength can be obtained, and even when using the latest technologies such as laser welding, the problem of the laser penetrating inside the electrode assembly A and melting the separator membrane or the active material can be prevented.

[0017] In addition, in the conventional tabless cylindrical battery, the positive electrode plain portion 10a is formed entirely on the upper side of the electrode assembly A. Therefore, when forming a beading portion by pushing the outer peripheral surface of the upper end of the battery housing inward, the peripheral edge region 34 of the upper end of the electrode assembly A is subjected to pressure by the battery housing. Such pressure may partially deform the electrode assembly A, and at this time, an internal short circuit may occur while the separator membrane 12 is torn. If a short circuit occurs inside the battery, there is a risk of the battery generating heat or exploding.

Summary of the Invention

Problems to be Solved by the Invention

[0018] The present invention was conceived under the background of the above-described prior art, and an object thereof is to provide an electrode assembly having an improved structure of a plain portion that can relieve the stress applied to the plain portion when the plain portions exposed at both ends of the electrode assembly are bent.

[0019] Another object of the present invention is to provide an electrode assembly in which the electrolyte injection passage is not blocked even when the plain portion is bent.

[0020] Still another object of the present invention is to provide an electrode assembly including a structure capable of preventing the upper end periphery of the electrode assembly from coming into contact with the inner surface of the battery housing when the upper end of the battery housing is beaded.

[0021] Furthermore, the present invention applies a segmented structure to the plain portion of the electrode, optimizes the dimensions (width, height, separation pitch) of the segments, and sufficiently increases the number of stacked segments in the region used as the welding target region, thereby improving the physical properties of the welding region. Another object is to provide an electrode assembly.

[0022] Moreover, when repeatedly forming cutting grooves along the winding direction in the plain portion of the electrode to form a plurality of segmented structures, the present invention optimizes the lower structure of the cutting grooves to improve the notching quality of the cutting grooves. Another object is to provide an electrode assembly.

[0023] Also, when repeatedly forming cutting grooves along the winding direction in the plain portion of the electrode to form a plurality of segmented structures, the present invention relatively adjusts the height of the plain portion below the cutting grooves and the height of the plain portion in the region adjacent to the core of the electrode assembly, so as to provide an electrode assembly in which the shape of the core does not collapse. Another object is to provide an electrode assembly.

[0024] Furthermore, the present invention applies a structure in which a current collector is welded over a large area to the bent surface region formed by bending the segments, thereby providing an electrode assembly with improved energy density and reduced resistance. Another object is to provide an electrode assembly.

[0025] Another object of the present invention is to provide a battery including a terminal and a current collector whose design is improved so that electrical wiring can be executed at the upper part.

[0026] Another object of the present invention is to provide a battery including an electrode assembly with an improved structure, a battery pack including the battery, and an automobile including the battery pack.

[0027] The technical problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems will be clearly understood by those skilled in the art from the following description of the invention.

Means for Solving the Problems

[0028] To achieve the above object, an electrode assembly according to an aspect of the present invention includes a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode, which are wound around a winding axis to define a core and an outer peripheral surface. The first electrode includes a first active material portion coated with an active material layer along the winding direction, and a first plain portion not coated with an active material layer and exposed outside the separator. The first plain portion includes a first portion adjacent to the core of the electrode assembly, a second portion adjacent to the outer peripheral surface of the electrode assembly, and a third portion between the first portion and the second portion. The third portion includes a plurality of segmented pieces spaced apart in the winding direction by a plurality of cutting grooves extending in the winding axis direction. The height of the first portion is relatively lower than the height of the plain portion at the lower end of the cutting groove.

[0029] In one aspect of the present invention, the height difference is a relative difference. The reference point for height measurement can be arbitrarily selected.

[0030] In one form, the reference point for height measurement can be the end of the active material layer.

[0031] An insulating coating layer may be provided at the boundary between the first plain portion and the active material layer.

[0032] In other forms, the reference point for height measurement may be the end of the insulating coating layer.

[0033] Based on the end of the active material layer or the insulating coating layer, the height of the first portion may be 0% to 95% compared to the height of the unpatterned portion at the lower end of the cutting groove.

[0034] Based on the end of the active material layer or the insulating coating layer, the height of the first portion may be 37.5% to 62.5% compared to the height of the unpatterned portion at the lower end of the cutting groove.

[0035] The height of the second portion may be relatively lower than the height of the unpatterned portion at the lower end of the cutting groove.

[0036] Based on the end of the active material layer or the insulating coating layer, the height of the second portion may be 0% to 95% compared to the height of the unpatterned portion at the lower end of the cutting groove.

[0037] Based on the end of the active material layer or the insulating coating layer, the height of the second portion may be 37.5% to 62.5% compared to the height of the unpatterned portion at the lower end of the cutting groove.

[0038] The current collector of the first electrode may be thinner than the current collector of the second electrode.

[0039] The current collector of the first electrode may be a copper foil, and the current collector of the second electrode may be an aluminum foil.

[0040] The first electrode may be a negative electrode.

[0041] To achieve the above object, a battery according to another aspect of the present invention includes an electrode assembly including at least one of the above-described features, an open end, and a bottom facing the open end, the electrode assembly being housed in a space between the open end and the bottom, a battery housing electrically connected to one of the first electrode and the second electrode and having a first polarity, a sealing body sealing the open end of the battery housing, and a terminal electrically connected to the other of the first electrode and the second electrode and having a second polarity with a surface exposed to the outside.

[0042] The sealing body includes a cap plate that seals the open end portion of the battery housing and a gasket that wraps around the periphery of the cap plate and is crimped to the open end portion of the battery housing, and the terminal having the second polarity can be the cap plate.

[0043] The battery further includes a current collector electrically connected to the non-coated portion of the first electrode having the first polarity and having at least a part of its periphery coupled to the side wall of the battery housing. In this case, the sealing body includes a cap plate and a gasket that wraps around the periphery of the cap plate and is crimped to the open end portion of the battery housing, and the battery housing is insulatingly attached to a through hole formed in the central portion of the bottom and may include a rivet terminal electrically connected to the second electrode and having the second polarity.

[0044] The cap plate may not have a polarity.

[0045] A technical problem according to an aspect of the present invention is also achieved by a battery pack including a plurality of the above-described batteries and an automobile including the same.

Advantages of the Invention

[0046] According to an aspect of the present invention, by using the non-coated portions protruding above and below the electrode assembly as electrode tabs, the internal resistance of the battery can be reduced and the energy density can be increased.

[0047] Further, according to one aspect of the present invention, by improving the structure of the non-patterned portion of the electrode assembly, the electrode assembly and the inner peripheral surface of the battery housing do not interfere with each other during the process of forming the beading portion of the battery housing, and internal short circuit of the cylindrical battery due to partial deformation of the electrode assembly can be prevented.

[0048] Further, according to one aspect of the present invention, by improving the structure of the non-patterned portion of the electrode assembly, it is possible to prevent the non-patterned portion from being torn when the non-patterned portion is bent, and to sufficiently increase the number of overlapping layers of the non-patterned portion to improve the welding strength of the current collector.

[0049] Further, according to one aspect of the present invention, by applying a segmented structure to the non-patterned portion of the electrode and optimizing the dimensions (width, height, separation pitch) of the segments, the number of stacked segments in the region used as the welding target region can be sufficiently increased, thereby improving the physical properties of the region where the current collector is welded.

[0050] Further, according to one aspect of the present invention, when repeatedly forming cutting grooves along the winding direction in the non-patterned portion of the electrode to form a plurality of segmented structures, the quality of the cutting grooves can be improved by optimizing the lower end structure of the cutting grooves.

[0051] Further, according to one aspect of the present invention, when repeatedly forming cutting grooves along the winding direction in the non-patterned portion of the electrode to form a plurality of segmented structures, the shape of the core can be prevented from collapsing by relatively adjusting the height of the non-patterned portion at the lower part of the cutting groove and the height of the non-patterned portion in the region adjacent to the core of the electrode assembly.

[0052] Further, according to one aspect of the present invention, by applying a structure in which a current collector is welded over a wide area to the bent surface region formed by bending the segments, an electrode assembly with improved energy density and reduced resistance can be provided.

[0053] Further, according to one aspect of the present invention, a cylindrical battery with an improved design that enables electrical wiring to be performed at the top can be provided.

[0054] Further, according to one aspect of the present invention, by improving the structure of the plain portion adjacent to the core of the electrode assembly, it is possible to prevent the cavities in the core of the electrode assembly from being blocked when the plain portion is bent, and to easily perform the electrolyte injection step and the welding step between the battery housing (or terminal) and the current collector.

[0055] Also, according to one aspect of the present invention, it is possible to provide a cylindrical battery having a structure with low internal resistance, prevention of internal short circuit, and improved welding strength between the current collector and the plain portion, a battery pack including the cylindrical battery, and an automobile.

[0056] In particular, the present invention can provide a cylindrical battery having a ratio of height to diameter of 0.4 or more and a resistance of 4 mΩ or less, a battery pack including the cylindrical battery, and an automobile.

[0057] The present invention also has various other effects, which will be described later with reference to embodiments. However, for effects that can be easily inferred by ordinary technicians, such explanations will be omitted.

[0058] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further understand the technical idea of the present invention together with the detailed description of the invention. Therefore, the present invention should not be construed as being limited only to the matters described in the drawings.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0060] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in this specification and the claims are not to be construed as being limited to their ordinary and dictionary meanings. The inventor himself interprets them in accordance with the meaning and concept corresponding to the technical idea of the present invention in accordance with the principle that he can appropriately define the concept of the terms in order to explain the invention in the best way.

[0061] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical ideas of the present invention. Therefore, there may be various equivalents and modifications that can replace them at the time of this application.

[0062] Also, for the purpose of assisting in the understanding of the invention, the attached drawings are not illustrated at an actual scale, and the dimensions of some components may be exaggerated. Also, the same reference numerals may be assigned to the same components in different embodiments.

[0063] The expression that two comparison targets are the same means "substantially the same". Therefore, "substantially the same" may include cases having a deviation regarded as a low level in the industry, for example, a deviation within 5%. Also, the fact that a certain parameter is uniform in a predetermined region means that it is uniform from an average point of view in the corresponding region.

[0064] Also, terms such as "first", "second", etc. are used to indicate various components, but these terms are not intended to limit the components. These terms are merely used to distinguish one component from another, and unless otherwise specified, the first component can also be the second component.

[0065] Throughout the specification, unless otherwise specified, each component can be singular or plural.

[0066] When any configuration is arranged "above (or below)" a component or "on (or under)" a component, it means not only that any configuration is arranged in contact with the upper surface (or lower surface) of the component, but also that other configurations can be interposed between the component and any configuration arranged above (or below) the component.

[0067] Also, when it is said that a certain component is "connected", "coupled", or "joined" to another component, it includes not only the case where the components are directly connected or joined to each other, but also the case where other components are "interposed" between the components, or the case where each component is "connected", "coupled", or "joined" through other components.

[0068] Throughout the specification, unless otherwise specified, "A and / or B" means A, B, or A and B, and "C to D" means C or more and D or less.

[0069] In this specification, for convenience of explanation, the direction along the length direction of the winding axis of the electrode assembly wound in a jelly roll shape is referred to as the axial direction (Y-axis). Also, the direction surrounding the winding axis is referred to as the circumferential direction or the outer circumferential direction (X-axis). Further, the direction approaching or moving away from the winding axis is referred to as the radial direction. Among these, in particular, the direction approaching the winding axis is referred to as the centripetal direction, and the direction moving away from the winding axis is referred to as the centrifugal direction.

[0070] First, an electrode assembly according to an embodiment of the present invention will be described. The electrode assembly may be a jelly roll type electrode assembly having a structure in which a sheet-like first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are wound in one direction. However, the present invention is not limited by the type of the electrode assembly.

[0071] Preferably, at least one of the first electrode and the second electrode includes a plain portion where the active material is not coated at the long side end portion in the winding direction. At least a part of the plain portion is itself used as an electrode tab. The plain portion includes a core side plain portion adjacent to the core of the electrode assembly, an outer peripheral side plain portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate plain portion interposed between the core side plain portion and the outer peripheral side plain portion.

[0072] Preferably, at least one of the core side plain portion and the outer peripheral side plain portion is relatively lower in height than the intermediate plain portion.

[0073] FIG. 4 is a plan view showing the structure of an electrode 60 according to an embodiment of the present invention.

[0074] Referring to FIG. 4, the electrode 60 of the embodiment includes a current collector 41 made of a metal foil and an active material layer 42. The metal foil may be a conductive metal, such as aluminum or copper, and is appropriately selected according to the polarity of the electrode 60. The active material layer 42 is formed on at least one surface of the current collector 41. The active material layer 42 is formed along the winding direction (X axis). The electrode 60 includes a plain portion 43 at the long side end portion in the winding direction (X axis). The plain portion 43 is a partial region of the current collector 41 not coated with the active material. The region of the current collector 41 where the active material layer 42 is formed may be referred to as an active material portion.

[0075] In the electrode 60, the width of the active material portion in the short side direction of the current collector 41 may be 50 mm to 120 mm, and the length of the active material portion in the long side direction of the current collector 41 may be 3 m to 5 m. Therefore, the ratio of the short side to the long side of the active material portion may be 1.0% to 4.0%.

[0076] Preferably, in the electrode 60, the width of the active material portion in the short side direction of the current collector 41 can be 60 mm to 70 mm, and the length of the active material portion in the long side direction of the current collector 41 can be 3 m to 5 m. Therefore, the ratio of the short side to the long side of the active material portion can be 1.2% to 2.3%.

[0077] The ratio of the short side to the long side of the active material portion is significantly smaller than 6% to 11%, which is the ratio of the short side to the long side of the active material portion of the electrode used in a cylindrical battery having a form factor of 1865 or 2170.

[0078] Preferably, an insulating coating layer 44 can be formed at the boundary between the active material layer 42 and the blank portion 43. The insulating coating layer 44 is formed so as to overlap at least a part of the boundary between the active material layer 42 and the blank portion 43. The insulating coating layer 44 prevents a short circuit between two electrodes of opposite polarities facing each other with a separator interposed therebetween. The insulating coating layer 44 can cover the boundary portion between the active material layer 42 and the blank portion 43 with a width of 0.3 mm to 5 mm. The width of the insulating coating layer 44 can vary along the winding direction of the electrode 60. The insulating coating layer 44 contains a polymer resin and may contain an inorganic filler such as SiO 2 , Al 2 O 3 . The portion of the current collector 41 covered by the insulating coating layer 44 can be regarded as a blank portion because it is not a region coated with the active material layer.

[0079] The blank portion 43 includes a core-side blank portion B1 adjacent to the core side of the electrode assembly, an outer peripheral-side blank portion B3 adjacent to the outer peripheral side of the electrode assembly, and an intermediate blank portion B2 interposed between the core-side blank portion B1 and the outer peripheral-side blank portion B3.

[0080] The core-side blank portion B1, the outer peripheral-side blank portion B3, and the intermediate blank portion B2 can be defined as the blank portion of the region adjacent to the core side, the blank portion of the region adjacent to the outer peripheral side, and the blank portion of the other region excluding these when the electrode 60 is wound as a jelly roll type electrode assembly, respectively.

[0081] Hereinafter, the core-side blank portion B1, the outer peripheral-side blank portion B3, and the intermediate blank portion B2 are referred to as the first portion, the second portion, and the third portion, respectively.

[0082] As an example, the first portion B1 may be a blank portion of an electrode region including the innermost winding turn, and the second portion B3 may be a blank portion of an electrode region including the outermost winding turn. The winding turns can be counted based on the core-side end of the electrode assembly.

[0083] As another example, the boundary between B1 / B2 can be appropriately defined at a point where the height (or change pattern) of the blank portion substantially changes from the core side to the outer peripheral side of the electrode assembly, or at a point of a predetermined percentage (e.g., 5%, 10%, 15% of the radius, etc.) based on the radius of the electrode assembly.

[0084] The boundary between B2 / B3 can be defined at a point where the height (or change pattern) of the blank portion substantially changes from the outer peripheral side to the core side of the electrode assembly, or at a point of a predetermined percentage (e.g., 85%, 90%, 95% of the radius, etc.) based on the radius of the electrode assembly. If the boundaries between B1 / B2 and B2 / B3 are specified, the third portion B2 can be automatically specified.

[0085] If only the boundary between B1 / B2 is specified, the boundary between B2 / B3 can be appropriately selected at a point near the outer peripheral side of the electrode assembly. As an example, the second portion can be defined as a blank portion of an electrode region constituting the outermost winding turn. On the other hand, if only the boundary between B2 / B3 is specified, the boundary between B1 / B2 can be appropriately selected at a point near the core side of the electrode assembly. As an example, the first portion B1 can be defined as a blank portion of an electrode region constituting the innermost winding turn.

[0086] It does not exclude the intervention of other structures between the first portion B1 and the third portion B2. Also, it does not exclude the intervention of other structures between the third portion B2 and the second portion B3.

[0087] The height of the non-patterned portion 43 is not constant and is relatively different in the winding direction (X-axis). That is, the height (length in the Y-axis direction) of the second portion B3 is 0 or more and can be relatively lower than that of the first portion B1 and / or the third portion B2. Here, the height of each portion can be the average height or the maximum height, and the same applies hereinafter. In the winding direction, the length of the third portion B2 is even longer than that of the first portion B1 and the second portion B3.

[0088] The electrode 60 is such that the heights of the first portion B1 and the second portion B3 are 0 or more and are relatively lower than that of the third portion B2. Also, the height of the first portion B1 and the height of the second portion B3 can be the same or different.

[0089] The width d of the first portion B1 B1 is designed by applying the condition of not blocking the core of the electrode assembly when the non-patterned portion of the third portion B2 is bent toward the core side. The core means a cavity existing at the winding center of the electrode assembly.

[0090] As an example, the width d of the first portion B1 B1 can increase in proportion to the bending length of the non-patterned portion closest to the core.

[0091] Preferably, the width d of the first portion B1 B1 can be set such that the radial width of the winding turn formed by the first portion B1 is equal to or greater than the bending length of the non-patterned portion region closest to the core. In a modified example, the width d of the first portion B1 B1 can be set such that the value obtained by subtracting the radial width of the winding turn formed by the first portion B1 from the bending length of the non-patterned portion region closest to the core is less than 0 or 10% or less of the core radius.

[0092] In a specific example, when the electrode 60 is used to manufacture an electrode assembly of a cylindrical battery with a form factor 4680, the width d of the first portion B1 B1 can be set to 180 mm to 350 mm according to the diameter of the core of the electrode assembly and the bending length of the non-patterned portion region closest to the core.

[0093] The plain part of Part 3 B2 may include a plurality of segmented pieces 61 in at least a partial section. The plurality of segmented pieces 61 may have heights that increase stepwise from the core side toward the outer peripheral side. Alternatively, the heights of the plurality of segmented pieces 61 may be maintained the same from the core side toward the outer peripheral side. The plurality of segmented pieces 61 have the form of a geometric figure whose width decreases from the lower part to the upper part. Preferably, the geometric figure is a trapezoid. As will be described later, the form of the geometric figure can be variously deformed into a quadrilateral, a parallelogram, etc.

[0094] The segmented piece 61 may be notched with a laser. The segmented piece 61 can be formed by a known metal foil cutting process such as ultrasonic cutting or punching.

[0095] When bending the non-coated portion 43, in order to prevent damage to the active material layer 42 and / or the insulating coating layer 44, it is preferable to provide a predetermined gap between the lower end of the cutting groove between the divided segments 61 (G in Fig. 5a) and the active material layer 42. This is because when the non-coated portion 43 is bent, stress is concentrated near the lower end of the cutting groove 63. The gap can vary along the winding direction of the electrode 60. The gap is preferably 0.2 mm to 4 mm, more preferably 1.5 mm to 2.5 mm. By adjusting the gap within the above numerical range, it is possible to prevent the active material layer 42 and / or the insulating coating layer 44 near the lower end of the cutting groove 63 from being damaged by the stress generated during the bending process of the non-coated portion 43. Also, the gap can prevent damage to the active material layer 42 and / or the insulating coating layer 44 due to the tolerance during the notching or cutting of the divided segments 61. In one direction parallel to the winding direction, the gap can be substantially the same or can vary. In the latter case, the plurality of divided segments can have the gap vary individually, in group units, or in two or more group units along one direction parallel to the winding direction. The lower end of the cutting groove 63 and the insulating coating layer 44 can be separated by 0.5 mm to 2.0 mm. In one direction parallel to the winding direction, the separation distance between the lower end of the cutting groove 63 and the insulating coating layer 44 can be substantially the same or can vary. In the latter case, the plurality of divided segments can have the separation distance vary individually, in group units, or in two or more group units along one direction parallel to the winding direction. When the electrode 60 is wound, the end portion of the insulating coating layer 44 in the winding axis (Y-axis) direction can be positioned in the range of -2 mm to 2 mm along the winding axis direction with reference to the end portion of the separator. The insulating coating layer 44 can prevent short-circuiting between two electrodes of opposite polarities facing each other with the separator interposed therebetween, and can support the bending point when the divided segment 61 is bent. To improve the short-circuit prevention effect between the two electrodes, the insulating coating layer 44 can be exposed outside the separator. Also, to further maximize the short-circuit prevention effect between the two electrodes, the width of the insulating coating layer 44 can be increased so that the end portion of the insulating coating layer 44 in the winding axis (Y-axis) direction is positioned above the lower end of the cutting groove 63.In one example, the end of the insulating coating layer 44 in the winding axis direction may be located within the range of -2 mm to +2 mm with reference to the lower end of the cutting groove 63. The thickness of the insulating coating layer 44 may be thinner than that of the active material layer. In this case, a gap may exist between the surface of the insulating coating layer 44 and the separator.

[0096] In one form, the plurality of divided segments 61 may form a plurality of divided segment groups from the core side toward the outer peripheral side. At least one of the width, height, and separation pitch of the divided segments belonging to the same divided segment group may be substantially the same. Preferably, the width, height, and separation pitch of the divided segments belonging to the same divided segment group may be the same as each other.

[0097] Preferably, the width and height of the divided segments belonging to the same divided segment group may be substantially the same.

[0098] In other forms, the separation pitch of the plurality of divided segments may gradually or stepwise increase or vice versa from the core side toward the outer peripheral side in group units or in two or more group units.

[0099] In still other forms, the separation pitch of the plurality of divided segments may gradually or stepwise increase and then gradually or stepwise decrease or vice versa from the core side toward the outer peripheral side in group units or in two or more group units.

[0100] In still other forms, the gap between the lower end of the cutting groove 63 and the insulating coating layer 44 or the active material layer 42 of the plurality of divided segments may gradually or stepwise increase or vice versa from the core side toward the outer peripheral side.

[0101] In yet another form, in the plurality of segmented pieces, the gap between the lower end of the cutting groove 63 and the insulating coating layer 44 or the active material layer 42 may gradually or stepwise increase or gradually or stepwise decrease from the core side toward the outer peripheral side. Or, vice versa, it may be the case.

[0102] FIG. 5a is a diagram showing the definitions of the width D, height H, and separation pitch P of the trapezoidal segmented piece 61, and FIG. 5b is a partially enlarged view showing the lower part of the cutting groove 63.

[0103] Referring to FIGS. 5a and 5b, the width D, height H, and separation pitch P of the segmented piece 61 are designed to prevent the plain portion 43 near the bending point from being broken during the bending process of the plain portion 43 and to prevent abnormal deformation of the plain portion 43 while sufficiently increasing the number of overlapping layers of the plain portion 43 to ensure sufficient welding strength.

[0104] The bending of the segmented piece 61 is performed at line G passing through the lower end of the cutting groove 63 or above it. The cutting groove 63 enables smooth and easy bending of the segmented piece 61 in the radial direction of the electrode assembly.

[0105] The segmented pieces 61 are arranged on both sides of the cutting groove 63. The cutting groove 63 includes a side portion 63a and a round portion 63b of the segmented piece 61. The side portion 63a extends linearly. The side portion 63a forms an acute angle with the winding direction. The round portion 63b may have a radius of curvature. Both ends of the round portion 63b are smoothly connected to the side portion 63a.

[0106] The width D of the segmented piece 61 is defined as the length between two points where two straight lines extending from the side portion 63a of the segmented piece 61 and a straight line G extending in the winding direction passing through the lower end of the round portion 63b intersect.

[0107] The height H of the segmented piece 61 is defined as the shortest distance between the uppermost side of the segmented piece 61 and a straight line extending in the winding direction passing through the lower end of the round portion 63b.

[0108] The separation pitch P of the segmentation slice 61 is defined as the length between two points where a straight line L1 connecting both side ends of the round portion 63b and a straight line L2 extending from both side portions 63a on both sides of the cutting groove 63 intersect, as shown in FIG. 5b. That is, the distance between two points where the curvature radius starts to change at the lower part of the side portions 63a on both sides of the cutting groove 63 corresponds to the separation pitch P.

[0109] The separation pitch P of the segmentation slice 61 can be 0.05 mm to 2.0 mm, preferably 0.5 mm to 1.0 mm.

[0110] The round portion 63b can be substantially the same as a circle having the separation pitch P as the diameter. Alternatively, the round portion 63b can approximately follow the pattern of a circle having the separation pitch P as the diameter. Alternatively, the round portion 63b connects the side portions of the segmentation slice 61 located on both sides of the cutting groove 63, and the curvature radius of the round portion 63b can gradually increase and then gradually decrease from the side portion of one segmentation slice 61 toward the side portion of the other segmentation slice 61.

[0111] When a round portion 63b that is substantially the same as a circle having the separation pitch P as the diameter, a round portion 63b that approximately follows the circle, or a round portion 63b whose curvature radius gradually increases and then gradually decreases is provided at the lower part of the cutting groove 63, the notching quality can be improved during the notching process of the segmentation slice 61.

[0112] In the embodiment of the present invention, when the round portion 63b approximately follows a circle, it means that the curvature radius of the round portion 63b gradually changes within a range of 20% or less based on the radius of a circle having the separation pitch P as the diameter, and smoothly connects the lower ends of the side portions 63a on both sides of the cutting groove 63.

[0113] Referring further to FIG. 5a, preferably, the width D of the segmentation slice 61 is 1 mm or more. If D is less than 1 mm, when the segmentation slice 61 is bent toward the core side, there is a possibility that the segmentation slice 61 does not overlap enough to ensure sufficient welding strength, or an empty space (gap) may occur.

[0114] Preferably, the width D of the slit piece 61 can be adaptively adjusted according to the radius of the winding turn where the slit piece 61 is located so that the slit piece 61 can be easily overlapped in the radial direction when the slit piece 61 is bent toward the core side of the electrode assembly.

[0115] FIG. 6a is a view showing, with reference to the center O of the core of the electrode assembly, an arc A formed by the lower end of the slit piece 61 (line segment D in FIG. 5a) where the width D of the slit piece 61 is defined when the electrode 60 is wound according to an embodiment of the present invention. ab ) 1 A 2

[0116] Referring to FIG. 6a, the arc A 1 A 2 has a length corresponding to the width D of the slit piece 61 and has a circumferential angle Φ with reference to the center of the core of the electrode assembly. The circumferential angle Φ can be defined as the angle between two line segments connecting the two ends of the arc A 1 A 2 and the center O of the core on a plane perpendicular to the winding axis passing through the arc A 1 A 2 .

[0117] When the lengths of the arcs A 1 A 2 of the slit piece 61 are the same, the circumferential angle Φ decreases as the radius r of the winding turn where the slit piece 61 is located increases. Conversely, when the circumferential angles Φ of the slit piece 61 are the same, the lengths of the arcs A 1 A 2 increase proportionally as the radius r of the winding turn where the slit piece 61 is located increases.

[0118] The circumferential angle Φ affects the bending quality of the slit piece 61. In the drawing, the solid-line arrow indicates the direction of the force applied to bend the slit piece 61, and the dotted-line arrow indicates the direction in which the slit piece 61 is bent. The bending direction is the direction toward the center O of the core.

[0119] ​The circumferential angle Φ of the segment 61 can be 45° or less, preferably 30° or less, according to the radius r of the winding turn where the segment 61 is located, in order to improve the uniformity of bending and prevent the occurrence of cracks.

[0120] In one form, the circumferential angle Φ of the segment 61 can increase or decrease gradually or stepwise along the radial direction of the electrode assembly within the above numerical range. In another form, the circumferential angle Φ of the segment 61 can increase gradually or stepwise along the radial direction of the electrode assembly within the above numerical range and then decrease gradually or stepwise, and vice versa is also possible. In still another form, the circumferential angle Φ of the segment 61 can be substantially the same along the radial direction of the electrode assembly within the above numerical range.

[0121] According to experiments, when the circumferential angle Φ of the segment 61 exceeds 45°, the bending pattern of the segment 61 will not be uniform. The difference in the forces applied to the central part and the side part of the segment 61 becomes large, and the pressing of the segment 61 in the circumferential direction will not be uniform. Also, if the pressing force is increased for the sake of bending uniformity, there is a risk of cracks occurring in the plain part 43 near the cutting groove 63.

[0122] In one example, the circumferential angles Φ of the segments 61 included in the electrode 60 are substantially the same, and the width of the segment 61 can increase proportionally as the radius r of the winding turn where the segment 61 is located increases. Substantially the same means either completely the same or having a deviation of less than 5%.

[0123] For example, when the radius of the electrode assembly is 22 mm, the radius of the core is 4 mm, and the segment 61 is arranged from the winding turn located at the 7 - mm radius point, when the circumferential angle Φ of the segment 61 is constant at 28.6°, the width D of the segment 61 can increase proportionally according to the radius r of the winding turn where the segment 61 is located as shown in Table 1 below. That is, the width of the segment 61 can increase at substantially the same ratio by 0.5 mm each time the radius r of the winding turn increases by 1 mm.

[0124]

Table 1

[0125] Preferably, the width D(r) of the segment 61 located in the winding turn with a radius of r based on the center O of the core of the electrode assembly can be determined within a range that satisfies the following Equation 1. [Equation 1] 1 ≦ D(r) ≦ (2×π×r / 360°)×45°

[0126] Preferably, for each of the plurality of segments 61, as the radius r of the winding turn in which the segment 61 is located increases with respect to the center of the core of the electrode assembly, the width D(r) in the winding direction can gradually or stepwise increase, or vice versa.

[0127] In another form, for each of the plurality of segments 61, as the radius r of the winding turn in which the segment 61 is located increases with respect to the center of the core of the electrode assembly, the width D(r) in the winding direction can gradually or stepwise increase within the range of 1 mm to 11 mm, or vice versa.

[0128] In yet another form, for each of the plurality of segments 61, as the radius r of the winding turn in which the segment 61 is located increases with respect to the center of the core of the electrode assembly, the width D(r) in the winding direction can gradually or stepwise increase and then gradually or stepwise decrease, or vice versa.

[0129] In yet another form, for each of the plurality of segments 61, as the radius r of the winding turn in which the segment 61 is located increases with respect to the center of the core of the electrode assembly, the width D(r) in the winding direction can gradually or stepwise increase within the range of 1 mm to 11 mm and then gradually or stepwise decrease, or vice versa.

[0130] In yet another embodiment, as the radius r of the winding turn in which the segment 61 is located increases, the rate at which the width D(r) of the segment 61 changes can be the same or different.

[0131] In yet another embodiment, as the radius r of the winding turn in which the segment 61 is located increases, the rate at which the width D(r) of the segment 61 changes in the range of 1 mm to 11 mm can be the same or different.

[0132] Referring further to FIG. 5a, the height H of the segment 61 can be 2 mm or more. If D2 is less than 2 mm, when the segment 61 is bent toward the core side, there is a risk that the segment 61 will not overlap to ensure sufficient welding strength, or that an empty space (gap) will be generated.

[0133] The height H of the segment 61 can be determined by applying the condition that the core is not blocked when the segment 61 is bent toward the core side. Preferably, the height H of the segment 61 can be adjusted so that 90% or more of the diameter of the core is open to the outside.

[0134] Preferably, the height H of the segment 61 can gradually increase from the core side to the outer peripheral side according to the radius of the winding turn in which the segment 61 is located and the radius of the core.

[0135] In one example, if the height H of the segment 61 gradually increases in N steps from h 1 to h N as the radius of the winding turn increases, and the k-th height h k (where k is a natural number from 1 to N) of the segment 61, and the starting radius of the winding turn including the segment 61 having the height h k is r k , and the radius of the core is r c , then the height h 1 ~h N of the segment 61 can be determined so that the following formula 2 is satisfied. [Formula 2] 2 mm ≤ h k ≤ r k - α × r c(Preferably, α is 0.90 to 1)

[0136] The height h of the segmented piece 61 k When it satisfies Formula 2, even if the segmented piece 61 is bent toward the core side, 90% or more of the diameter of the core can be opened to the outside.

[0137] As an example, the overall winding turn radius of the electrode assembly is 22 mm, the height of the segmented piece 61 starts from 3 mm, and the height of the segmented piece 61 increases in order to 3 mm, 4 mm, 5 mm, 6 mm each time the radius of the winding turn including the segmented piece 61 increases by 1 mm, and the height can be substantially maintained at 6 mm in the remaining winding turns. That is, among the radii of the overall winding turns, the radial width of the height variable section of the segmented piece 61 is 3 mm, and the remaining radius section corresponds to the height uniform section.

[0138] In this case, the radius r of the core of the electrode assembly c The starting radii r 1 、r 2 、r 3 、r 3 of the winding turns including the segmented piece 61 having heights of 3 mm, 4 mm, 5 mm, and 6 mm according to are as shown in Table 2 below when α is 1 and the equal sign condition is applied in the right inequality.

[0139]

Table 2

[0140] When the segmented piece 61 is disposed at the radius positions shown in Table 2, even if the segmented piece 61 is bent toward the core side, the core is not blocked by the segmented piece 61. On the other hand, r 1 、r 2 、r 3 、r 3 shown in Table 2 can be shifted toward the core side according to the α value. In one example, when α is 0.90, r 1 、r 2 、r 3 、r 3can be shifted toward the core by 10% of the core radius. In this case, when the segment 61 is bent toward the core, 10% of the core radius is blocked by the segment 61. 1 , r 2 , r 3 , r 3 is the limit value of the position where the segment 61 starts. Therefore, the position of the segment 61 can be shifted a predetermined distance toward the outer periphery from the radius shown in Table 2. 1 , h 2 , h 3 , h 4 , core radius r c , the radius r of the winding turn where the segment 61 begins to appear 1 , r 2 , r 3 , r 3 FIG.

[0141] With reference to Table 2 and FIG. 6b, for example, the radius r c When is 3m, 3mm(h 1 ), 4mm(h 2 ), 5mm(h 3 ) and 6mm(h 4 ) the starting radius r of the winding turn that includes the segment 61 having a height 1 , r 2 , r 3 and r 3 may be 6 mm, 7 mm, 8 mm, and 9 mm, respectively, and the height of the segment 61 may be maintained at 6 mm from the radius of 9 mm to the last winding turn. 1 ) may not include the segment 61. In such an example, the segment 61 is adjacent to the core C and has a height of 3 mm (h 1 Since the portion 61 of the core C is located at a radius of 6 mm from the winding turn, even if the portion 61 is bent toward the core C, it covers only the radius section of 3 mm to 6 mm and does not substantially block the core C. The position of the portion 61 is determined according to the α value of the formula 2. c It can be shifted to the core C side within 10% of the

[0142] In other forms, the height of the segment 61 may increase at the same or different ratios as the starting radius r of the winding turn where the segment 61 is located increases with respect to the center of the core of the electrode assembly.

[0143] Preferably, the height H of the segment 61 satisfies Equation 2 and the maximum height of the segment 61 may be limited.

[0144] FIG. 6c is a conceptual diagram for determining the maximum value h with respect to the height H of the segment 61 in the variable height range of the segment 61. max

[0145] Referring to FIG. 6c, in the winding structure of the electrode assembly, the electrode E including the segment 61 1 is opposed to the electrode E of the opposite polarity with the separation membrane S interposed therebetween in the radial direction. 2 The electrode E 1 is coated with the active material layer E 1,active on both sides, and the electrode E 2 is also coated with the active material layer E 2,active on both sides. For electrical insulation, the end S end of the separation membrane S may further extend outward by a length corresponding to the insulation gap W 2 from the end E 2,end of the electrode E. Also, the end of the electrode E gap does not extend outward beyond the end of the electrode E 1 for electrical insulation. Therefore, a section corresponding to the insulation gap W 2 must be secured at the lower end of the plain portion 43. Also, when the electrodes E gap and the separation membrane S are wound, the end S 1 of the separation membrane S meanders. Therefore, in order for the segment 61 to be exposed outside the separation membrane S, a section W 2 corresponding to the minimum meandering margin of the separation membrane S must be allocated to the plain portion 43. Also, in order to cut the segment 61, a minimum cutting scrap margin W end is required at the end of the current collector foil. margin,min scrap,min ​​must be assigned. Therefore, the maximum height h of the segment 61 in the height variable range of the segment 61 max can be determined by the following Equation 3. In Equation 3, W foil corresponds to the width of the current collector foil before the current collector foil is cut. [Equation 3] h max =W foil -W scrap,min -W margin,min -W gap

[0146] Preferably, when the first electrode is the positive electrode, the insulation gap W gap can be 0.2 mm to 6 mm. Also, when the first electrode is the negative electrode, the insulation gap W gap can be 0.1 mm to 2 mm.

[0147] Preferably, the minimum cutting scrap margin W scrap,min can be 1.5 mm to 8 mm. The minimum cutting scrap margin W scrap,min may not be assigned depending on the process of forming the segment 61. For example, the cutting groove 63 can be formed so that the upper side of the segment 61 coincides with the upper side of the current collector foil. In this case, in Equation 3, W scrap,min can be 0.

[0148] Preferably, the minimum meandering margin W of the separation film margin,min can be 0 to 1 mm.

[0149] As an example, the minimum cutting scrap margin W scrap,min is 1.5 mm, and the minimum meandering margin W of the separation film S margin,min can be 0.5 mm. Under such conditions, when the width W of the current collector foil before forming the segment 61 foil is 8 mm to 12 mm and the insulation gap W gap is 0.6 mm, 0.8 mm, and 1.0 mm, the results of calculating the maximum height h of the segment 61 using Equation 3 max are as shown in Table 3 below.

[0150]

Table 3

[0151] Referring to Table 3, the maximum height h of the segmented slice 61 in the height variable range of the segmented slice 61 max can be set to 10 mm. Therefore, the height of the segmented slice 61 in the height variable range of the segmented slice 61 satisfies Equation 2 and can increase stepwise or gradually along the radial direction of the electrode assembly in the range of 2 mm to 10 mm. Further referring to FIG. 5a, the separation pitch P of the segmented slice 61 can be adjusted in the range of 0.05 to 2 mm, preferably 0.5 mm to 1.0 mm. When the separation pitch P is less than 0.05 mm, when the electrode 60 travels during a winding process or the like, there is a risk that cracks may occur in the non-patterned portion 43 near the lower end of the cutting groove 63 due to stress. On the other hand, when the separation pitch P exceeds 2 mm, when the segmented slice 61 is bent, there is a risk that the segmented slice 61 may not overlap to ensure sufficient welding strength, or an empty space (gap) may occur.

[0152] On the other hand, when the current collector 41 of the electrode 60 is made of aluminum, it is more preferable to set the separation pitch P to 0.5 mm or more. When the separation pitch P is 0.5 mm or more, even when the electrode 60 travels at a speed of 100 mm / sec or more under a tension of 300 gf or more in a winding process or the like, it is possible to prevent cracks from occurring at the lower part of the cutting groove 63.

[0153] According to the experimental results, when the current collector 41 of the electrode 60 is an aluminum foil with a thickness of 15 μm and the separation pitch P is 0.5 mm or more, when the electrode 60 travels under the above running conditions, cracks do not occur at the lower part of the cutting groove 63.

[0154] The plurality of segment pieces 61 may have a lower inner angle θ that increases from the core side toward the outer peripheral side. As an example, the plurality of segment pieces 61 may have a lower inner angle θ that gradually or stepwise increases from the core side toward the outer peripheral side. The lower inner angle θ is an angle between a straight line extending from the lower end of the cutting groove 63 and a straight line extending from the side portion 63a of the segment piece 61. When the segment piece 61 is symmetric about the left and right, the lower inner angles θ on the left and right sides are substantially the same.

[0155] If the radius of the electrode assembly increases, the radius of curvature increases. If the lower inner angle θ of the segment piece 61 increases as the radius of the electrode assembly increases, when the segment piece 61 is bent, the stress generated in the radial direction and the circumferential direction can be relaxed. Further, if the lower inner angle θ increases, when the segment piece 61 is bent, both the area overlapping with the inner segment piece 61 and the number of overlapping layers increase, so that the welding strength can be ensured uniformly in the radial direction and the circumferential direction, and the bent surface region can be formed flat.

[0156] Preferably, the lower inner angle θ may be determined by the radius of the winding turn in which the segment piece 61 is located and the width D of the segment piece 61.

[0157] FIG. 6d is a schematic diagram for explaining a mathematical formula for determining the lower inner angle θ of the segment piece 61.

[0158] Referring to FIG. 6d, it is ideal that the sides of the segment piece 61 coincide with the line segments AE and DE that connect the center E of the core with A and D, which are the two ends of the line segment AD corresponding to the width D of the segment piece 61.

[0159] When the sides of the segment piece 61 extend in the most ideal direction, the lower inner angle θ of the segment piece 61 refer can be approximately determined from the width D of the segment piece 61 and the radius r of the winding turn in which the segment piece 61 is located using the following mathematical formula 4, assuming that the line segment EF is approximately equal to the line segments AE and DE. [Mathematical formula 4] [Number]

[0160] The angle of Equation 4 is the ideal reference angle of the lower inner angle θ of the segment 61. On the other hand, there is a separation pitch P between adjacent segments 61 located in the same winding turn. The length of the separation pitch P is denoted as p. Since the separation pitch P exists between adjacent segments 61, a tolerance of 50% of the separation pitch P can be given to the lower inner angle θ. That is, the width of the upper end side BC of the segment 61 can increase by up to p / 2 to the upper end side B'C'. The lower inner angle θ' reflecting the tolerance can be expressed by the following Equation 5. The lower inner angle θ refer is the ideal reference angle ∠BAG, and the lower inner angle θ' is the angle ∠B'AG' reflecting the tolerance due to the separation pitch P. In Equation 5, H is the height of the segment 61, and p corresponds to the separation pitch. refer [Equation 5]

Number

[0161] Preferably, the lower inner angle θ of the segment 61 located in each winding turn of the electrode assembly can satisfy the following Equation 6. Thereby, when the segment 61 is bent toward the center of the core of the electrode assembly, adjacent segments 61 in the circumferential direction do not interfere with each other, and smooth bending is possible. [Equation 6]

Number

[0162] As an example, when the electrode 60 forms a winding structure with a diameter of 22 mm and a core radius of 4 mm, the lower inner angle of the segment 61 can gradually or stepwise increase in the range of 60° to 85° in the height variable section.

[0163] As another example, for a plurality of segments 61, the lower inner angle θ can gradually or stepwise increase from the core side to the outer peripheral side in one or two or more group units.

[0164] ​On one hand, the lower left inner corner and the lower right inner corner of the split piece 61 may not be equal. Even so, at least one lower inner corner θ on one side can be designed to satisfy the above-mentioned formula 6.

[0165] Referring further to FIG. 4, the width d of the first portion B1 B1 is designed such that when the split piece 61 of the third portion B2 is bent toward the core side, the core of the electrode assembly is opened outward by 90% or more based on its diameter. The width d of the first portion B1 B1 can increase in proportion to the bending length of the split piece 61 in Group 1. The bending length corresponds to the length from the bending point to the upper end side of the split piece 61. Preferably, when the electrode 60 is used to manufacture the electrode assembly of a cylindrical battery with a form factor of 4680, the width d of the first portion B1 B1 can be set to 180 mm to 350 mm according to the diameter of the core of the electrode assembly and the height of the split piece 61 included in Group 1.

[0166] The bending point of the split piece 61 can be set at a line passing through the lower end of the cutting groove 63 or a point separated from that line by a predetermined distance upward. If the split piece 61 is bent toward the core side at a point separated from the lower end of the cutting groove 63 by a predetermined distance, the overlapping of the split pieces in the radial direction becomes easier. When the split piece 61 is bent, the split piece on the outside presses against the split piece on the inside with reference to the center of the core. At this time, if the bending point is separated from the lower end of the cutting groove 63 by a predetermined distance, the overlapping of the split pieces is more easily performed while the inner split piece is pressed in the winding axis direction by the outer split piece. The separation distance of the bending point can preferably be 1 mm or less. Since the minimum height of the split piece is 2 mm, the ratio of the separation distance of the bending point to the minimum height can be 50% or less.

[0167] In one example, the width of each split piece group can be designed to constitute the same winding turn of the electrode assembly. Here, the winding turn can be counted based on the end of the first portion B1 in the state where the electrode 60 is wound.

[0168] In another modification, the width of each slit piece group can be designed to constitute at least one winding turn of the electrode assembly.

[0169] In yet another modification, the width and / or height and / or separation pitch of the slit pieces 61 belonging to the same slit piece group can increase or decrease gradually and / or stepwise and / or irregularly within the group or between adjacent groups.

[0170] Groups 1 to 8 are merely an example of the slit piece groups included in the third portion B2. The number of groups, the number of slit pieces 61 included in each group, and the width of the group can be preferably adjusted so that the slit pieces 61 overlap multiplicatively to maximize the dispersion of stress during the bending process of the non-patterned portion 43 and sufficiently ensure the welding strength with the current collector.

[0171] When there is one slit piece group, the height of the slit pieces 61 in the third portion B2 can be uniform.

[0172] The slit structure of the third portion B2 can be extended to the second portion B3 (see the dotted line). In this case, the second portion B3 can also include a plurality of slit pieces, similar to the third portion B2. Preferably, the slit structure of the second portion B3 can be substantially the same as the outermost slit piece group of the third portion B2. In this case, the slit pieces included in the second portion B3 and the third portion B2 can have substantially the same width, height, and separation pitch. As a modification, the slit pieces of the second portion B3 can have a width and / or height and / or separation pitch larger than that of the third portion B2.

[0173] In the third portion B2, with reference to the winding direction of the electrode 60, the section where the height of the slit pieces 61 increases stepwise (Groups 1 to 7) can be defined as the height variable section of the slit pieces, and the last slit piece group (Group 8) can be defined as the height uniform section where the height of the slit pieces is maintained uniformly.

[0174] That is, in the third portion B2, the height of the slit pieces 61 is h 1 to h NWhen increasing step by step up to h 1 ~h N-1 (where N is a high index and a natural number of 2 or more), the section where the segment 61 having a height is arranged corresponds to a height variable section, and h N The section where the segment 61 having a height corresponds to a height uniform section. The ratio of the height variable section to the height uniform section with respect to the length of the electrode 60 in the winding direction will be described later with reference to specific examples.

[0175] When the electrode 60 is used to manufacture the electrode assembly of a cylindrical battery with a form factor of 4680, the width d of the first part B1 B1 can be 180 to 350 mm. The width of group 1 can be 35 to 40% of the width of the first part B1. The width of group 2 can be 130 to 150% of the width of group 1. The width of group 3 can be 120 to 135% of the width of group 2. The width of group 4 can be 85 to 90% of the width of group 3. The width of group 5 can be 120 to 130% of the width of group 4. The width of group 6 can be 100 to 120% of the width of group 5. The width of group 7 can be 90 to 120% of the width of group 6. The width of group 8 can be 115 to 130% of the width of group 7. The width d of the second part B3 B3 can be 180 to 350 mm as well as the width of the first part B1.

[0176] The reason why the widths of groups 1 to 8 do not show a constant increase or decrease pattern is that although the width of the segment gradually increases from group 1 to group 8, the number of segments included in each group is limited to an integer, and the thickness of the electrode has a slight deviation in the winding direction. Therefore, the number of segments can decrease in a specific segment group. Therefore, the width of the group can show an irregular change pattern as exemplified above from the core side to the outer peripheral side.

[0177] That is, in the circumferential direction of the electrode assembly, when the winding widths for each of three continuously adjacent segment groups are W1, W2, and W3 respectively, it may include a combination of segment groups where W3 / W2 is smaller than W2 / W1.

[0178] In the above-described specific example, Groups 4 to 6 correspond to the above case. 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%, and the value is smaller than 120 to 130%.

[0179] On the other hand, referring to FIG. 5c, the height H of the plain portion of the first part B1 of the electrode 60 B1 may be relatively lower than the height H of the plain portion at the lower end of the cutting groove 63. The height H g and the height H B1 are relative differences. The reference point for height measurement can be set arbitrarily. Preferably, the height H g and the height H B1 can be measured with reference to the end of the insulating coating layer 44 or the end of the active material layer 42. When the height H of the plain portion at the lower end of the cutting groove 63 is not constant, the height H g can be the average value, median value, maximum value, or minimum value of the height of the plain portion at the lower end of the cutting groove 63. g When the height H g is lower than the height H of the plain portion at the lower end of the cutting groove 63

[0180] B1 g B1 g when the electrode 60 is wound as an electrode assembly, it is possible to prevent the shape of the core from collapsing while the plain portion of the first part B1 near the core is irregularly bent.

[0181] B1 g B1 g The height H can be 95% or less, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, or 63% or less compared to the height H.

[0182] B1 B1is 0% or more, 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, or 37% or more compared to the height H g and can be up to 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, or 37% or more compared to the height H

[0183] The height H B1 The upper and lower limits can be selectively combined from the ranges described above. If the height H g changes, the height H B1 can also change

[0184] In an embodiment, when the height H g is 0.8 mm based on the end of the active material layer 42 or the insulating coating layer 44, the height H B1 can be 0 or more, 0.1 mm (12.5%) or more, 0.15 mm (18.8%) or more, 0.2 mm (25.0%) or more, 0.25 mm (31.3%) or more, 0.3 mm (37.5%) or more, 0.35 mm (43.8%) or more, or 0.4 mm (50.0%) or more

[0185] In an embodiment, when the height H g is 0.8 mm based on the active material layer 42 or the insulating coating layer 44, the height H B1 can be 0.75 mm (93.8%) or less, 0.70 mm (87.5%) or less, 0.65 mm (81.3%) or less, 0.60 mm (75.0%) or less, 0.55 mm (68.8%) or less, 0.50 mm (62.5%) or less, or 0.45 mm (56.3%) or less

[0186] In an embodiment, the upper and lower limits of the height H B1 can be selectively combined from the ranges described above. If the height H g changes, the height H B1 can also change

[0187] In a preferred embodiment, when the height H g is 0.8 mm based on the end of the active material layer 42 or the insulating coating layer 44, the height H B1 can be 0.3 mm (37.5%) to 0.5 mm (62.5%)

[0188] Referring to FIG. 5d, selectively, the height H of the plain portion of the second portion B3 of the electrode 60 B3 is, similar to the first portion B1, the height H of the plain portion at the lower end of the cut groove 63 g can be lower. The height H B3 and the height H g The difference between them is a relative difference. The reference point for height measurement can be set arbitrarily. Preferably, the height H B3 and the height H g can be measured with reference to the end of the insulating coating layer 44 or the end of the active material layer 42.

[0189] The height H B3 is 95% or less, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, or 63% or less compared to the height H g can be.

[0190] The height H B3 is 0% or more, 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, or 37% or more compared to the height H g can be.

[0191] The height H B3 The upper and lower limits of can be selectively combined from the ranges described above. If the height H g changes, the height H B3 can also change.

[0192] In an embodiment, when the height H g is 0.8 mm with reference to the active material layer 42 or the insulating coating layer 44, the height H B3 is 0 or more, 0.1 mm (12.5%) or more, 0.15 mm (18.8%) or more, 0.2 mm (25.0%) or more, 0.25 mm (31.3%) or more, 0.3 mm (37.5%) or more, 0.35 mm (43.8%) or more, or 0.4 mm (50.0%) or more can be.

[0193] In an embodiment, when the height H g is 0.8 mm with reference to the active material layer 42 or the insulating coating layer 44, the height HB3 can be 0.75 mm (93.8%) or less, 0.70 mm (87.5%) or less, 0.65 mm (81.3%) or less, 0.60 mm (75.0%) or less, 0.55 mm (68.8%) or less, 0.50 mm (62.5%) or less, or 0.45 mm (56.3%) or less.

[0194] In the examples, the height H B3 The upper and lower limits can be selectively combined from the ranges described above. The height H g If it changes, the height H B3 can also change.

[0195] In a preferred example, when the height H g is 0.8 mm based on the active material layer 42 or the insulating coating layer 44, the height H B3 can be 0.3 mm (37.5%) to 0.5 mm (62.5%).

[0196] FIG. 5e is a photograph showing the winding state of the electrode assembly and the structure of the non-coated portion of the first portion B1 when the electrode 60 according to the embodiment of the present invention is a negative electrode and the height H of the non-coated portion at the lower end of the cutting groove 63 g is 0.8 mm based on the end of the active material layer, and the height H of the non-coated portion of the first portion B1 B1 is also 0.8 mm based on the end of the active material layer.

[0197] As shown in FIG. 5e, when the height H of the non-coated portion at the lower end of the cutting groove 63 g is equal to the height H of the non-coated portion of the first portion B1 B1 it can be confirmed that the shape of the core collapsed while the non-coated portion near the core was irregularly bent.

[0198] FIG. 5f is a photograph showing the winding state of the electrode assembly and the structure of the non-coated portion of the first portion B1 when the electrode 60 according to the embodiment of the present invention is a negative electrode and the height H of the non-coated portion at the lower end of the cutting groove 63 g is 0.8 mm based on the end of the active material layer, and the height H of the non-coated portion of the first portion B1 B1When it is 0.4 mm with reference to the end of the active material layer, it is a photograph showing the winding state of the electrode assembly and the structure of the plain part when the negative electrode near the core is unwound.

[0199] As shown in FIG. 5f, the height H of the plain part at the lower end of the cutting groove 63 g is lower than the height H of the plain part of the first portion B1 B1 It can be confirmed that the plain part near the core is not irregularly bent and the shape of the core has not collapsed.

[0200] Preferably, the height H of the plain part of the first portion B1 B1 is lower than the height H of the plain part at the lower end of the cutting groove 63 g The structure of making it lower is applicable to the negative electrode. When the current collector of the negative electrode and the current collector of the positive electrode are a copper foil and an aluminum foil, respectively, the thickness of the copper foil is designed to be thinner than the thickness of the aluminum foil. Also, since the length of the negative electrode is longer than that of the positive electrode and winding starts from the negative electrode, the radius of curvature of the winding start portion of the negative electrode is the smallest. Therefore, when the divided section 61 is bent, in the vicinity of the core of the electrode assembly, the plain part of the first portion B1 of the negative electrode is more vulnerable to the stress applied in the radial direction than the plain part of the first portion B1 of the positive electrode. Therefore, there is a possibility that the phenomenon that the plain part of the first portion B1 vulnerable to stress is irregularly bent may appear. However, by making the height H B1 of the first portion B1 lower than the height H g of the plain part at the lower end of the cutting groove 63, such a phenomenon can be prevented. On the other hand, the present invention does not exclude applying the structures shown in FIGS. 5c and 5d to the positive electrode.

[0201] According to still another modification, when the plain part 43 of the electrode 60 has a divided section structure, the electrode 60 may include a divided section omission section 64 in which a part of the plurality of divided sections is regularly or irregularly omitted, as shown in FIG. 7a.

[0202] Preferably, there may be a plurality of segment omission sections 64. As an example, the width of the segment omission section 64 may be constant from the core side toward the outer peripheral side. As another example, the width of the segment omission section 64 may increase or decrease regularly or irregularly from the core side toward the outer peripheral side. Preferably, the height of the plain portion existing in the segment omission section 64 may correspond to the height of the first portion B1 and / or the second portion B3.

[0203] The number of segments 61 existing between the segment omission sections 64 may be at least one. As shown in FIG. 7a, the electrode 60 may include a plain portion section in which the number of segments 61 existing between the segment omission sections 64 increases from the core toward the outer peripheral side.

[0204] Preferably, as shown in FIG. 7b, the width of the segment omission section 64 may be set such that when the electrode 60 is wound, the segments located in each winding turn are positioned within a preset independent region 66 with respect to the center C of the core of the electrode assembly 65.

[0205] That is, the plurality of segments 61 may be positioned within a plurality of independent regions 66 with respect to the center C of the core when the electrode assembly 65 is viewed in the winding axis direction. The number of independent regions 66 may vary to two, three, four, five, etc.

[0206] Preferably, the independent region 66 may be in a sector shape. In this case, the angles between the independent regions 66 may be substantially the same. Also, the circumferential angle δ of the independent region 66 may be 20° or more, optionally 25° or more, optionally 30° or more, optionally 35° or more, or optionally 40° or more.

[0207] In a modification, the independent region 66 may have a form of a geometric figure such as a square, a rectangle, a parallelogram, or a trapezoid.

[0208] In one embodiment of the present invention, the shape of the segment 61 can be variously deformed.

[0209] FIG. 8a is a plan view showing the structure of an electrode 70 according to another embodiment of the present invention.

[0210] Referring to FIG. 8a, the electrode 70 has substantially the same configuration except that the shape of the divided piece 61' is different from that of the above-described embodiment.

[0211] The divided piece 61' has a geometric shape in which the upper width and the lower width are substantially the same. Preferably, the divided piece 61' can be square-shaped.

[0212] FIG. 8b is a drawing showing the definition of the width, height, and separation pitch of the square-shaped divided piece 61', and FIG. 8c is a partial enlarged view showing an enlarged view of the lower part of the cutting groove 63.

[0213] Referring to FIGS. 8b and 8c, the width D, height H, and separation pitch P of the divided piece 61' are set so as to sufficiently increase the number of overlapping layers of the plain portion 43 and prevent abnormal deformation of the plain portion 43 in order to prevent the plain portion 43 from being torn during the bending process of the plain portion 43 and improve the welding strength with the current collector. Abnormal deformation means that the plain portion below the bending point cannot maintain a straight state and collapses and is deformed irregularly.

[0214] The width D of the divided piece 61' is defined as the length between two points where two straight lines L2 extending from the side portions 63a on both sides of the divided piece 61' intersect with a straight line G extending along the winding direction from the lower end of the rounded portion 63b of the cutting groove 63. The height H of the divided piece 61' is defined as the shortest distance between the uppermost end side of the divided piece 61' and the straight line G extending along the winding direction from the lower end of the rounded portion 63b of the cutting groove 63. The separation pitch P of the divided piece 61' is defined as the length between two points where a straight line L1 connecting both ends of the rounded portion 63b intersects with two straight lines L2 extending from the side portion 63a of the divided piece 61'.

[0215] Preferably, since the conditions regarding the width D, height H, and separation pitch P of the divided piece 61' are substantially the same as those of the above-described embodiment, repeated explanations are omitted. However, since the divided piece 61' is square-shaped, the lower inner angle of the divided piece 61' can be constant at 90°.

[0216] Meanwhile, as shown in FIG. 8d and FIG. 8e, the height H B1 and / or the height H of the blank portion of the second portion B3 B3 is the height H of the plain part at the bottom end of the cutting groove 63 g The effect obtained by adjusting the height of the non-coating portion in this manner is substantially the same as that of the above-described embodiment.

[0217] Height H of the plain area of ​​the first part B1 B1 and / or the height H of the blank portion of the second portion B3 B3 can be set substantially similarly to the above-described embodiment.

[0218] That is, the height H B1 and / or height H B3 is the height H g In comparison, it may be 95% or less, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, or 63% or less.

[0219] Height H B1 and / or height H B3 is the height H g In comparison, it may be 0% or more, 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, or 37% or more.

[0220] Height H B1 and / or height H B3 The upper and lower limits of the height H can be selectively combined from the above ranges. g If changes, the height H B1 and / or height H B3 may also change.

[0221] In the embodiment, the height H g is 0.8 mm based on the end of the active material layer 42 or the insulating coating layer 44, B1 and / or height H B3It can be 0 or more, 0.1 mm (12.5%) or more, 0.15 mm (18.8%) or more, 0.2 mm (25.0%) or more, 0.25 mm (31.3%) or more, 0.3 mm (37.5%) or more, 0.35 mm (43.8%) or more, or 0.4 mm (50.0%) or more.

[0222] In the embodiment, the height H g When it is 0.8 mm with reference to the end of the active material layer 42 or the insulating coating layer 44, the height H B1 and / or the height H B3 can be 0.75 mm (93.8%) or less, 0.70 mm (87.5%) or less, 0.65 mm (81.3%) or less, 0.60 mm (75.0%) or less, 0.55 mm (68.8%) or less, 0.50 mm (62.5%) or less, or 0.45 mm (56.3%) or less.

[0223] In the embodiment, the height H B1 and / or the height H B3 The upper and lower limits can be selectively combined from the ranges described above. If the height H g changes, the height H B1 and / or the height H B3 can also change.

[0224] In a preferred embodiment, when the height H g is 0.8 mm with reference to the end of the active material layer 42 or the insulating coating layer 44, the height H B1 and / or the height H B3 can be 0.3 mm (37.5%) to 0.5 mm (62.5%).

[0225] Similar to the electrode 60, the electrode 70 can also include a partial segment omission section 64 in which some of the plurality of segmented sections are regularly or irregularly omitted, as shown in FIG. 8f.

[0226] Also, when the electrode 70 including the partial segment omission section 64 is wound as an electrode assembly, the segmented sections can be located in a plurality of independent regions 66, as shown in FIG. 7b.

[0227] As in the above-described embodiments, when the third part B2 and the second part B3 include a plurality of segmented slices 61, 61', the shapes of the respective segmented slices 61, 61' can be variously deformed.

[0228] Preferably, the segmented slices can be deformed in various forms while satisfying at least one of the following conditions. Condition 1: The width of the lower part is wider than the width of the upper part. Condition 2: The width of the lower part is equal to the width of the upper part. Condition 3: The width is maintained the same from the lower part to the upper part. Condition 4: The width decreases from the lower part to the upper part. Condition 5: The width decreases and then increases from the lower part to the upper part. Condition 6: The width increases and then decreases from the lower part to the upper part. Condition 7: The width increases from the lower part to the upper part and then is maintained constant. Condition 8: The width decreases from the lower part to the upper part and then is maintained constant. Condition 9: One inner angle on the lower side of the segmented slice and the other inner angle are the same. Here, the inner angle can be defined as the angle formed by the side of the segmented slice with respect to the width direction of the lower part of the segmented slice. When the side is a curve, the inner angle is defined as the angle between the tangent line drawn at the lowermost point of the curve and the width direction of the lower part of the segmented slice. Condition 10: One inner angle on the lower side of the segmented slice and the other inner angle are different. Condition 11: One inner angle on the lower side of the segmented slice and the other inner angle on the lower side each have an acute angle, a right angle, or an obtuse angle. Condition 12: It is symmetric about the winding axis direction. Condition 13: It is asymmetric about the winding axis direction. Condition 14: The sides are linear. Condition 15: The sides are curved. Condition 16: The sides are convex outward. Condition 17: The sides are convex inward. Condition 18: The corners of the upper part and / or the lower part are of a structure where a straight line intersects a straight line. Condition 19: The corners of the upper part and / or the lower part are of a structure where a straight line intersects a curve. Condition 20: The upper and / or lower corners have a structure where curves intersect with curves. Condition 21: The upper and / or lower corners have a round structure.

[0229] FIG. 9 is a diagram exemplarily showing the form of a segmented piece according to a modification of the present invention.

[0230] As shown in the drawing, the segmented piece may have a form of various geometric figures with a dotted line connecting the bottoms of the cutting grooves on both sides as the base. The geometric figure has a structure in which at least one straight line, at least one curve, or a combination thereof is connected. As an example, the segmented piece may have a polygonal shape, a round pattern, or various forms in which these are combined.

[0231] Specifically, the segmented piece may be a trapezoid shape symmetrical about the left and right (round a); a trapezoid shape asymmetrical about the left and right (round b); a parallelogram shape (round c); a triangle shape (round l); a pentagon shape (round k); an arc shape (round e); or an ellipse shape (round f).

[0232] The form of the segmented piece is not limited to that shown in FIG. 9, and may be deformed into other polygonal shapes, other round shapes, or combinations thereof so as to satisfy at least one of the above-described Conditions 1 to 21.

[0233] In the polygonal shapes of the segmented piece, namely round a, round b, round c, round k, and round l, the upper and / or lower corners may have a shape where straight lines intersect with each other or a round shape (refer to the enlargement of the upper and lower corners of round a, see FIGS. 5b and 8b).

[0234] In the polygonal shapes of the segmented piece, namely round a, round b, round c, round k, and round l, and the round shapes of the segmented piece, namely round e and round f, one inner angle θ on the lower side 1 and the other inner angle θ 2 may be the same or different, and one inner angle θ on the lower side 1 and the other inner angle θ 2They can be acute angles, right angles, or obtuse angles respectively. An interior angle is an angle formed by the base and a side of a geometric figure. When the side is a curve, the straight line can be replaced by a tangent line extending from the intersection of the base and the side.

[0235] The shape of the side of a polygonal segment can be variously deformed.

[0236] As an example, the side of the segment in form circle a can be deformed into a curve bulging outward like form circle d, or into a curve concave inside the segment like form circle g or circle j.

[0237] As another example, the side of the segment in form circle a can be deformed into a broken line concave inside the segment like form circle h or circle i. Although not shown, the side of the segment in form circle a can be deformed into a broken line bulging outward.

[0238] In segments in form circles d, g, j, h, and i with variously deformed sides, the lower one - side interior angle θ 1 and the other - side interior angle θ 2 are the same or different, and the lower one - side interior angle θ 1 and the other - side interior angle θ 2 can be an acute angle, a right angle, or an obtuse angle respectively.

[0239] The width of the segment can have various change patterns from the lower part to the upper part.

[0240] As an example, the width of the segment pieces can be maintained constant from the lower part to the upper part (form round c). As another example, the width of the segment pieces can gradually decrease from the lower part to the upper part (forms round a, round b, round d, round e, round f, and round g). As yet another example, the width of the segment piece 61 can gradually decrease from the lower part to the upper part and then increase (forms round i and round j). As yet another example, the width of the segment pieces can gradually increase from the lower part to the upper part and then decrease (form round k). As yet another example, the width of the segment pieces can gradually decrease from the lower part to the upper part and then be maintained constant (form round h). Although not shown, the width of the segment pieces can gradually increase from the lower part to the upper part and then be maintained constant.

[0241] On the other hand, among the forms of the segment pieces illustrated in FIG. 9, the upper flat polygonal shape can be rotated 180°. As an example, when the form of the segment piece such as round a, round b, round d, or round g is rotated 180°, the width of the segment piece can gradually increase from the lower part to the upper part. As another example, when the form of the segment piece round h is rotated 180°, the width of the segment piece can be maintained constant from the lower part to the upper part and then gradually increase.

[0242] In the above-described embodiments (modifications), according to another form of the present invention, it is also possible to change the shape of the segment pieces 61, 61' along the region of the third part B2. As an example, a round shape (for example, semi-circular, elliptical, etc.) advantageous for stress dispersion can be applied to the section where stress is concentrated, and a polygonal shape (for example, quadrilateral, trapezoid, parallelogram, etc.) with the largest possible area can be applied to the section where stress is relatively low.

[0243] In yet another form, the plurality of segment pieces can have different forms individually, in group units, or in two or more group units along a direction parallel to the winding direction of the electrode assembly.

[0244] In the above-described embodiments (modification examples), the slitting structure of the third part B2 can also be applied to the first part B1. However, if the slitting structure is applied to the first part B1, depending on the radius of curvature of the core, when the slitting pieces 61, 61' of the third part B2 are bent, there may be a reverse forming phenomenon in which the end of the first part B1 bends to the outer peripheral side. Therefore, it is preferable not to apply the slitting structure to the first part B1, or, even if the slitting structure is applied, to consider the radius of curvature of the core and adjust the width and / or height and / or separation pitch of the slitting pieces 61, 61' to a level at which reverse forming does not occur.

[0245] Also, according to still another embodiment of the present invention, after the electrodes 60, 70 are wound as an electrode assembly, the slitting pieces exposed on the upper and lower sides of the electrode assembly can form a bent surface region while overlapping multiple times along the radial direction of the electrode assembly.

[0246] FIG. 10a is a schematic cross-sectional view showing a bent surface region F formed while the slitting piece 61 is bent toward the core C side of the electrode assembly 80. In FIG. 10a, only the left side of the cross-section of the bent surface region F is shown with reference to the winding axis of the electrode assembly 80. The bent surface region F can be formed on both the upper and lower portions of the electrode assembly 80. FIG. 10b is a perspective view schematically showing the electrode assembly 80 in which the bent surface region F is formed.

[0247] Referring to FIGS. 10a and 10b, the bent surface region F has a structure in which the slitting pieces 61 overlap in a plurality of layers in the winding axis direction. The overlapping direction is the winding axis direction (Y-axis). Section circle 1 is a slitting piece omission section (first part B1) without slitting pieces, and section circles 2 and 3 are sections where the winding turns including the slitting pieces are located. Section circle 2 is a height variable section where the height of the slitting piece 61 changes, and section circle 3 is a height uniform section where the height of the slitting piece is maintained uniformly up to the outer periphery of the electrode assembly. As will be described later, the radial lengths of section circle 2 and section circle 3 can vary. On the other hand, at least one winding turn including the outermost winding turn may not include the slitting structure in the plain part (second part B3). In this case, the second part B3 can be excluded from section circle 3.

[0248] In the circular section 2, the height of the segment 61 is the radius r of the electrode assembly 80 1 ~r N in the section with the minimum height h 1 (=h min ) to the maximum height h N (=h max ) and can change step by step. The height variable section where the height of the segment 61 changes is r 1 ~r N . From the radius r N to the radius R of the electrode assembly 80, the height of the segment 61 is maintained uniformly at h N . That the height is uniform means that the deviation of the height is within 5%.

[0249] At any radius position in the circular section 2 and the circular section 3, the number of layers of the segment 61 changes depending on the radius position. Also, the number of layers of the segment 61 can change depending on the width of the circular section 2, the minimum height h of the segment in the height variable section of the segment 61 1 and the maximum height h N , and the height change amount Δh of the segment 61. The number of layers of the segment 61 is the number of segments intersecting the virtual line when a virtual line is drawn in the winding axis direction from any radius position of the electrode assembly 80

[0250] Preferably, by adjusting the height, width and separation pitch of the segment 61 according to the radius of the winding turn including the segment 61, the number of layers of the segment 61 at each position in the bent surface region F can be optimized according to the required welding strength of the current collector

[0251] First, when the minimum height h of the segment in the height variable section (circular section 2) of the segment 61 is the same, how the number of layers of the segment 61 changes along the radial direction of the bent surface region F due to the change in the maximum height h 1 of the segment 61 will be described with specific examples N .

[0252] Electrode assemblies of Examples 1-1 to 1-7 were prepared. The electrode assembly of the example has a radius of 22 mm and a core diameter of 4 mm. The positive and negative electrodes included in the electrode assembly have the electrode structure shown in FIG. 4. That is, the form of the segmented piece is trapezoidal. The second portions B3 of the positive and negative electrodes do not include segmented pieces. The length of the second portion B3 is 3% to 4% of the total length of the electrode. The positive electrode, negative electrode, and separator were wound by the method described with reference to FIG. 2. The number of winding turns is between 48 turns and 56 turns, but the number of winding turns in the example is 51 turns. The thicknesses of the positive electrode, negative electrode, and separator are 149 μm, 193 μm, and 13 μm, respectively. The thicknesses of the positive and negative electrodes are the thicknesses including the thickness of the active material layer. The thicknesses of the positive current collector and the negative current collector are 15 μm and 10 μm, respectively. The lengths of the positive and negative electrodes in the winding direction are 3948 mm and 4045 mm, respectively.

[0253] In each example, for the height variable range (circle 2) of the segmented piece 61, the minimum height of the segmented piece 61 was set to 3 mm so as to start from a radius of 5 mm. Also, in each example, the height of the segmented piece 61 was increased by 1 mm each time the radius increased by 1 mm, and the maximum height of the segmented piece 61 was variously changed from 4 mm to 10 mm.

[0254] Specifically, in Example 1-1, the height variable range (circle 2) of the segmented slice 61 is 5 mm to 6 mm, and the height of the segmented slice 61 changes from a radius of 3 mm to 4 mm. In Example 1-2, the height variable range (circle 2) of the segmented slice 61 is 5 mm to 7 mm, and the height of the segmented slice 61 changes from 3 mm to 5 mm. In Example 1-3, the height variable range (circle 2) of the segmented slice 61 is 5 mm to 8 mm, and the height of the segmented slice 61 changes from 3 mm to 6 mm. In Example 1-4, the height variable range (circle 2) of the segmented slice 61 is 5 mm to 9 mm, and the height of the segmented slice 61 changes from 3 mm to 7 mm. In Example 1-5, the height variable range (circle 2) of the segmented slice 61 is 5 mm to 10 mm, and the height of the segmented slice 61 changes from 3 mm to 8 mm. In Example 1-6, the height variable range (circle 2) of the segmented slice 61 is 5 mm to 11 mm, and the height of the segmented slice 61 changes from 3 mm to 9 mm. In Example 1-7, the height variable range (circle 2) of the segmented slice 61 is 5 mm to 12 mm, and the height of the segmented slice 61 changes from 3 mm to 10 mm. In Examples 1-1 to 1-7, the height of the segmented slice 61 is uniform from the radius corresponding to the upper limit of the height variable range (circle 2) to the outer circumference. As an example, in Example 1-7, the height of the segmented slice 61 is uniform at 10 mm from a radius of 12 mm to 22 mm. On the other hand, in the electrode assembly of the comparative example, the height of the segmented slice 61 was maintained at a single height of 3 mm from a radius of 5 mm to a radius of 22 mm.

[0255] Figure 11a is a graph showing the result of counting the number of stacked segmented slices along the radial direction in the bent surface region F of the positive electrode formed on the upper part of the electrode assemblies according to Examples 1-1 to 1-7 and the comparative example. Substantially the same result is shown in the bent surface region of the negative electrode. The horizontal axis of the graph is the radius based on the center of the core, and the vertical axis of the graph is the number of stacked segmented slices counted at each radius point. The same applies to FIGS. 11b and 11c described later.

[0256] Referring to Fig. 11a, the average layer number interval b1 of the segmented slices commonly appears in Examples 1-1 to 1-7 and Comparative Example 1. The average layer number interval b1 is the radius interval of the flat region in each graph. The length of the average layer number interval b1 increases as the maximum height of the segmented slice decreases, and the average layer number interval b1' of the comparative example is the longest. On the other hand, the layer number of the segmented slice increases as the maximum height h N of the segmented slice increases. That is, if the maximum height h N of the segmented slice increases and the width of the height variable interval (circle 2) of the segmented slice increases, the layer number of the segmented slice increases while the width of the average layer number interval b1 decreases. Outside the average layer number interval b1, a layer number decreasing interval b2 appears where the layer number of the segmented slice decreases as the radius increases. The layer number decreasing interval b2 is the radius interval where the layer number of the segmented slice decreases as the radius of the electrode assembly increases. The average layer number interval b1 and the layer number decreasing interval b2 are adjacent in the radial direction and are complementary to each other. That is, if the length of one interval increases, the length of the other interval decreases. Also, in the layer number decreasing interval b2, the amount of decrease in the layer number is proportional to the distance from the average layer number interval b1.

[0257] From the side of the layer number of the segmented slice, in Examples 1-1 to 1-7, the layer number of the segmented slice in the average layer number interval b1 of the segmented slice is 10 or more. The region where the layer number of the segmented slice is 10 or more can be set as a preferable welding target region. The welding target region is the section where at least a part of the current collector is welded.

[0258] In Examples 1-1 to 1-7, the average layer number interval b1 starts from the radius point where the height variable interval (circle 2) of the segmented slice starts. That is, the height variable interval (circle 2) starts from a radius of 5 mm and extends to the outer peripheral side.

[0259] Table 4 below shows the results of calculating, for Examples 1-1 to 1-7 and Comparative Example 1, the ratio of the length of the segment-omitted section (c, circle 1 in Fig. 10a) to the radius (b - a) of the electrode assembly excluding the core with respect to the positive electrode, the ratio (e / f) of the length of the layer-number average section b1 to the length (f) from the radius point (5 mm) where the layer-number average section starts to the outermost point (22 mm) of the electrode assembly, the ratio (d / f) of the length of the height-variable section (d) of the segment to the length (f) from the radius point (5 mm) where the layer-number average section starts to the outermost point (22 mm) of the electrode assembly, the ratio (h) of the length of the electrode region corresponding to the segment-omitted section (first part B1) to the total length of the electrode, the ratio (i) of the length of the electrode region corresponding to the height-variable section to the total length of the electrode, and the ratio (j) of the electrode region corresponding to the height-uniform section to the total length of the electrode, etc.

[0260] The negative electrode is substantially the same as the positive electrode in other parameters except that it shows a difference of 0.1 to 1.2% with respect to the parameter h. The sum of the ratios h, i, and j is slightly different from 100%. The reason is that there is a section without a segment in the second part B3 corresponding to the non-patterned part on the outer peripheral side of the electrode. For example, in the case of Example 1-1, there is no segment in the second part B3 corresponding to about 4% of the total length of the electrode. In Table 4, a to f are parameters based on the length in the radial direction, and h, i, and j are parameters based on the longitudinal direction of the electrode before the electrode is wound as an electrode assembly. Also, the parameters corresponding to the ratio (%) are values rounded off to the first decimal place. These are substantially the same in Tables 5 and 6 described later.

[0261]

Table 4

[0262] Referring to Examples 1-1 to 1-7 in Table 4, the number of laminations of the segmented slices is 11 to 26, and the ratio (d / f) of the height variable interval (d) to the radius interval (f) containing the segmented slices is 6% to 41%. Also, the ratio (e / f) of the lamination number uniform interval (e) to the radius interval (f) containing the segmented slices is 47% to 82%. Further, the ratio (c / (b-a)) of the segmented slice omission interval (c, circle 1 in Fig. 10a) to the radius (b-a) of the electrode assembly excluding the core is 15%. Also, the ratio of the length of the electrode region corresponding to the segmented slice omission interval (first part B1) to the total length of the electrode is 6%, the ratio of the length of the electrode region corresponding to the height variable interval to the total length of the electrode is 3% to 32%, and the ratio of the length of the electrode region corresponding to the height uniform interval to the total length of the electrode is 59% to 87%. The number of laminations (g) in the lamination number uniform interval is 10 or more for all of Examples 1-1 to 1-7. The lamination number uniform interval (e) decreases as the height variable interval (d) of the segmented slices increases, but the number of laminations (g) of the segmented slices increases in the lamination number uniform interval (e). Preferably, the lamination number uniform interval (e) in which the number of laminations (g) of the segmented slices is 10 or more can be set as the welding target region.

[0263] Cylindrical batteries having form factors of 1865 and 2170 have a radius of the electrode assembly of about 9 mm to 10 mm. Therefore, for conventional cylindrical batteries, as in Examples 1-1 to 1-7, the radial length of the segmented section (f) cannot be ensured at the 17 mm level, and the length of the lamination number uniform interval (e) in which the number of laminations of the segmented slices is 10 or more cannot be ensured at the 8 mm to 14 mm level. In a conventional cylindrical battery, when the radius of the core is designed to be 2 mm, the same as in Examples 1-1 to 1-7, the radius interval in which the segmented slices can be arranged is only substantially 7 mm to 8 mm. Also, in a conventional cylindrical battery, the length in the winding direction of the electrode is at the 600 mm to 980 mm level. Such a short electrode length is only about 15% to 24% of the electrode lengths (positive electrode 3948 mm, negative electrode 4045 mm) used in Examples 1-1 to 1-7. Therefore, the numerical ranges for parameters h, i, and j cannot be easily derived from the design specifications of conventional cylindrical batteries.

[0264] Next, when the maximum height h of the segmented slice in the height variable range of the segmented slice (circle 2 in Fig. 10a) is the same, how the number of stacked layers of the segmented slice changes along the radial direction of the bent surface region F will be described with specific examples according to the change in the minimum height h of the segmented slice. N of the segmented slice. 1 will be described with specific examples.

[0265] The electrode assemblies of Examples 2-1 to 2-5 have a radius of 22 mm and the core C has a diameter of 4 mm. The minimum height h in the height variable range of the segmented slice 61 (circle 2 in Fig. 10a) 1 is the same as 4 mm, and the maximum height h N was changed in 1 mm increments from 6 mm to 10 mm. Therefore, the electrode assemblies of Examples 2-1 to 2-5 have widths of the height variable range of the segmented slice (circle 2 in Fig. 10a) of 2 mm, 3 mm, 4 mm, 5 mm, and 6 mm, respectively, and the segmented slice omission range (circle 1 in Fig. 10a) is a radial range from a radius of 2 mm to 6 mm.

[0266] The electrode assemblies of Examples 3-1 to 3-4 have a radius of 22 mm and the core C has a diameter of 4 mm. The minimum height h in the height variable range of the segmented slice 61 (circle 2 in Fig. 10a) 1 is the same as 5 mm, and the maximum height h N was changed in 1 mm increments from 7 mm to 10 mm. Therefore, the electrode assemblies of Examples 3-1 to 3-4 have widths of the height variable range of the segmented slice (circle 2 in Fig. 10a) of 2 mm, 3 mm, 4 mm, and 5 mm, respectively, and the segmented slice omission range (circle 1 in Fig. 10a) is a radial range from a radius of 2 mm to 7 mm.

[0267] The electrode assemblies of Examples 4-1 to 4-3 have a radius of 22 mm and the core C has a diameter of 4 mm. The minimum height h in the height variable range of the segmented slice 61 (circle 2 in Fig. 10a) 1 is the same as 6 mm, and the maximum height h NIt was changed in 1 mm units from 8 mm to 10 mm. Therefore, in the electrode assemblies of Examples 4-1 to 4-3, the widths of the height variable sections (circle 2 in Fig. 10a) of the segmented slices are 2 mm, 3 mm, and 4 mm respectively, and the segmented slice omission section (circle 1 in Fig. 10a) is a radius section from a radius of 2 mm to 8 mm.

[0268] The electrode assemblies of Examples 5-1 to 5-2 have a radius of 22 mm and the core C has a diameter of 4 mm. The minimum height h in the height variable section (circle 2 in Fig. 10a) of the segmented slice 61 1 is the same as 7 mm, and the maximum height h N was changed in 1 mm units from 9 mm to 10 mm. Therefore, in the electrode assemblies of Examples 5-1 to 5-2, the widths of the height variable sections (circle 2 in Fig. 10a) of the segmented slices are 2 mm and 3 mm respectively, and the segmented slice omission section (circle 1 in Fig. 10a) is a radius section from a radius of 2 mm to 9 mm.

[0269] Fig. 11b is a graph showing the result of counting the number of stacked segmented slices measured along the radial direction in the bent surface region F of the positive electrode formed on the upper part of the electrode assemblies according to Examples 2-1 to 2-5, Examples 3-1 to 3-4, Examples 4-1 to 4-3, Examples 5-1 and 5-2. Substantially the same result is shown in the bent surface region of the negative electrode.

[0270] In Fig. 11b, graph (a) shows the result of counting the number of stacked segmented slices along the radial direction in the bent surface region F for Examples 2-1 to 2-5, graph (b) for Examples 3-1 to 3-4, graph (c) for Examples 4-1 to 4-3, and graph (d) for Examples 5-1 and 5-2.

[0271] Referring to Fig. 11b, a stacked number uniform section b1 of the segmented slices commonly appears in all examples. The stacked number uniform section b1 is a radius section of a flat region in the graph. The length of the stacked number uniform section b1 is the minimum height h of the segmented slice 1 is the same, and increases as the maximum height h of the segmented slice N decreases. Also, the length of the stacked number uniform section b1 is the maximum height h of the segmented slice NWhen they are the same, the minimum height h of the segmented slice 1 increases as it decreases. On the other hand, in the uniform lamination number interval b1, the lamination number of the segmented slice is the maximum height h of the segmented slice N increases as it increases. Also in the examples, a lamination number decreasing interval b2 appears adjacent to the uniform lamination number interval b1.

[0272] In the examples, the lamination number of the segmented slice in the uniform lamination number interval b1 is all 10 or more. Preferably, the region where the lamination number of the segmented slice is 10 or more can be set as a preferable welding target region.

[0273] In the examples, the uniform lamination number interval b1 starts from the radius point where the height variable interval of the segmented slice (circle 2 in FIG. 10a) starts. In Examples 2-1 to 2-5, the height variable interval of the segmented slice (circle 2 in FIG. 10a) starts from 6 mm and extends to the outer peripheral side. In Examples 3-1 to 3-4, the height variable interval of the segmented slice (circle 2 in FIG. 10a) starts from 7 mm and extends to the outer peripheral side. In Examples 4-3 to 4-3, the height variable interval of the segmented slice (circle 2 in FIG. 10a) starts from 8 mm and extends to the outer peripheral side. In Examples 5-1 and 5-2, the height variable interval of the segmented slice (circle 2 in FIG. 10a) starts from 9 mm and extends to the outer peripheral side.

[0274] In Table 5 below, for Examples 2-1 to 2-5, Examples 3-1 to 3-4, Examples 4-1 to 4-3, Examples 5-1 and 5-2, the ratio (e / f) of the length of the uniform lamination number interval to the length from the radius point (6 mm, 7 mm, 8 mm, 9 mm) where the uniform lamination number interval starts to the outermost point (22 mm) of the electrode assembly, and the ratio (d / f) of the length of the height variable interval (circle 2) of the segmented slice to the length from the radius point (6 mm, 7 mm, 8 mm, 9 mm) where the uniform lamination number interval starts to the outermost point (22 mm) of the electrode assembly, etc. The results of calculating various parameters including are shown.

[0275]

Table 5

[0276] Referring to Examples 2-5, 3-4, 4-3, and 5-2 in Table 5 together with FIGS. 10a and 11b, the maximum height h of the segmented slice in the height variable section (circle 2) N is the same at 10 mm, but the minimum height h of the segmented slice 1 is 4 mm, 5 mm, 6 mm, 7 mm, increasing by 1 mm each time, and the length of the height variable section (circle 2) is 6 mm, 5 mm, 4 mm, 3 mm, decreasing by 1 mm each time. In the four examples, the ratio (e / f) of the layer number uniform section is the largest at 69% in Example 2-5 and the smallest at 38% in Example 5-2, and the number of layers in the layer number uniform section is all equal. From the results shown in Table 5, when the maximum height h of the segmented slice N is the same, it can be seen that as the minimum height h of the segmented slice 1 decreases and the width of the height variable section (circle 2) of the segmented slice increases, the width of the layer number uniform section also proportionally increases. The reason is that the smaller the minimum length h of the segmented slice 1 is, the closer the radius point where the segmented slice starts is to the core side while the region where the segmented slice is laminated expands to the core side.

[0277] Referring to Table 5, it can be seen that the number of layers of the segmented slice is 16 - 26, the ratio (d / f) of the height variable section (circle 2) of the segmented slice is 13% - 38%, and the ratio (e / f) of the layer number uniform section is 31% - 69%. Also, the ratio (c / (b - a)) of the segmented slice omission section (circle 1) to the radius (b - a) of the electrode assembly excluding the core is 20% - 35%. Also, the ratio of the length of the electrode region corresponding to the segmented slice omission section (circle 1) to the total length of the electrode is 10% - 20%, the ratio of the length of the electrode region corresponding to the height variable section (circle 2) to the total length of the electrode is 6% - 25%, and the ratio of the length of the electrode region corresponding to the height uniform section (circle 3) to the total length of the electrode is 62% - 81%.

[0278] Cylindrical batteries having form factors of 1865 and 2170 have an electrode assembly with a radius of approximately 9 mm to 10 mm. Therefore, as in the embodiment, the radial length of the cut section interval (f) cannot be ensured at a level of 13 mm to 16 mm, and while ensuring the length of the cut section omission interval (c, circle 1) to be about 4 mm to 7 mm, it is impossible to ensure the length of the layer number uniform interval (e) where the number of layers of the cut sections is 10 or more at a level of 5 mm to 11 mm. In a conventional cylindrical battery, when the radius of the core is designed to be 2 mm as in the embodiment, the radius interval where the cut sections can be arranged is only substantially 7 mm to 8 mm. Also, in a conventional cylindrical battery, the length in the winding direction of the electrode is at a level of 600 mm to 980 mm. Such a short electrode length is only about 15% to 24% of the electrode lengths in the embodiment (positive electrode 3948 mm, negative electrode 4045 mm). Therefore, the numerical ranges for parameters h, i, and j cannot be easily derived from the design specifications of the conventional cylindrical battery.

[0279] Next, when the minimum height h 1 and the maximum height h N of the cut sections are the same in the height variable interval (circle 2) of the cut sections, how the number of layers of the cut sections changes along the radial direction of the bent surface region F will be described with specific examples based on the core C diameter of the electrode assembly.

[0280] The electrode assemblies of Examples 6-1 to 6-6 have a radius of 22 mm and the core C has a radius of 4 mm. The minimum height h 1 of the cut sections in the height variable interval (circle 2) of the cut sections 61 is the same as 3 mm, and the maximum height h N of the cut sections was changed in 1 mm increments from 5 mm to 10 mm. Therefore, the electrode assemblies of Examples 6-1 to 6-6 have widths of the height variable intervals (circle 2) of the cut sections of 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm respectively, and the cut section omission interval (circle 1) is the radius interval from a radius of 4 mm to 7 mm.

[0281] The electrode assemblies of Examples 7-1 to 7-6 have a radius of 22 mm, and the radius of the core C is 2 mm. The minimum height h of the segment in the height variable section (circle 2) of the segment 61 1 is the same as 3 mm, and the maximum height h of the segment N was changed in 1-mm increments from 5 mm to 10 mm. Therefore, in the electrode assemblies of Examples 7-1 to 7-6, the widths of the height variable sections (circle 2) of the segments are 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm, respectively, and the segment omission section (circle 1) is the same for all radius sections from a radius of 2 mm to 5 mm.

[0282] FIG. 11c is a graph showing the result of counting the number of stacked segments measured along the radial direction in the bent surface region F of the positive electrode formed on the upper part of the electrode assemblies according to Examples 6-1 to 6-6 and Examples 7-1 to 7-6. Substantially the same results appear in the bent surface region of the negative electrode.

[0283] In FIG. 11c, graph (a) shows the result of counting the number of stacked segments measured along the radial direction in the bent surface region F for Examples 6-1 to 6-6, and graph (b) shows the result for Examples 7-1 to 7-6.

[0284] Referring to FIG. 11c, a stacked segment number uniform section b1 commonly appears in all examples. The stacked segment number uniform section b1 is the radius section of the flat region in the graph. The length in the radial direction of the stacked segment number uniform section b1 increases as the maximum height h of the segment 1 decreases when the minimum height h of the segment N is the same. On the other hand, in the stacked segment number uniform section b1, the number of stacked segments increases as the maximum height h of the segment N increases. In the examples, a stacked segment number decreasing section b2 is confirmed adjacent to the stacked segment number uniform section b1.

[0285] In the examples, the number of stacked segments in the stacked segment number uniform section b1 is all 10 or more. Preferably, the region where the number of stacked segments is 10 or more can be set as a preferable welding target region.

[0286] In the examples, the stacked number average section b1 starts from the radial position where the height variable section (circle 2) of the sliced section starts. In the cases of Examples 6-1 to 6-6, the radius where the height variable section (circle 2) of the sliced section starts is 7 mm, and in the cases of Examples 7-1 to 7-6, the radius where the height variable section (circle 2) of the sliced section starts is 5 mm.

[0287] In Table 6 below, for Examples 6-1 to 6-6 and Examples 7-1 to 7-6, the ratio (e / f) of the length of the stacked number average section to the length from the radial position (7 mm, 5 mm) where the stacked number average section starts to the outermost position (22 mm) of the electrode assembly, the ratio (d / f) of the length of the height variable section (circle 2) of the sliced section to the length from the radial position (7 mm, 5 mm) where the stacked number average section starts to the outermost position (22 mm) of the electrode assembly, and other calculation results of various parameters are shown.

[0288]

Table 6

[0289] Referring to FIG. 10a and Examples 6-6 and 7-6 in Table 6, the minimum height h of the sliced section in the height variable section (circle 2) of the sliced section 1 and the maximum height h NThey are the same at 3 mm and 10 mm respectively. However, in Example 6-6, the radius of the core is 2 mm larger than that in Example 7-6. Therefore, compared with Example 7-6, the lamination number average section (e) and the cut section (f) in Example 6-6 are 2 mm smaller, and the lamination number of the cut sections in the lamination number average section is the same. Such a result is due to the difference in the radius of the core. From the results shown in Table 6, when the width of the height variable section (circle 2) of the cut section is the same, it can be seen that the smaller the radius (a) of the core, the smaller the ratio (d / f) of the height variable section (circle 2), while the ratio (e / f) of the lamination number average section increases. Referring to Table 6, it can be seen that the lamination number of the cut section is 13-26, the ratio (d / f) of the height variable section (circle 2) of the cut section is 12%-47%, and the ratio (e / f) of the length of the lamination number average section is 40%-76%. Also, the ratio (c / (b-a)) of the cut section omission section (circle 1) to the radius (b-a) of the electrode assembly excluding the core is 15%-17%. Also, the ratio of the length of the electrode region corresponding to the cut section omission section (circle 1) to the total length of the electrode is 6%, the ratio of the length of the electrode region corresponding to the height variable section (circle 2) to the total length of the electrode is 7%-32%, and the ratio of the length of the electrode region corresponding to the height uniform section (circle 3) to the total length of the electrode is 59%-83%.

[0290] Cylindrical batteries having form factors of 1865 and 2170 have a radius of the electrode assembly of approximately 9 mm to 10 mm. Therefore, as in the embodiment, it is not possible to ensure a radial length of the slit section (f) at a level of 15 mm to 17 mm, and while ensuring a length of the slit omission section (circle 1) of about 3 mm, it is not possible to ensure a length of the layer number uniform section (e) where the number of layers of the slices is 10 or more at a level of 6 mm to 13 mm. In a conventional cylindrical battery, when the radius of the core is designed to be the same as 2 mm to 4 mm in the embodiment, the radial section where the slit sections can be arranged is only substantially 5 mm to 8 mm. Also, in a conventional cylindrical battery, the length in the winding direction of the electrode is at a level of 600 mm to 980 mm. Such a short electrode length is only about 15% to 24% of the electrode lengths (positive electrode 3948 mm, negative electrode 4045 mm) in the embodiment. Therefore, the numerical ranges for parameters h, i, and j cannot be easily derived from the design specifications of the conventional cylindrical battery.

[0291] Taking into comprehensive consideration the data in Tables 4 to 6, the number of layers of the slit sections in the layer number uniform section of the slit sections can be 11 to 26. Also, the ratio (d / f) of the height variable section (circle 2) of the slit sections can be 6% to 47%. Also, the ratio (e / f) of the layer number uniform section can be 31% to 82%. Also, the ratio of the length of the slit omission section (circle 1) to the radius of the electrode assembly excluding the core (c / (b - a)) can be 15% to 35%. Also, the ratio of the length of the electrode region corresponding to the slit omission section (circle 1) to the total length of the electrode (length in the winding direction) can be 6% to 20%. Also, the ratio of the length of the electrode region corresponding to the height variable section (circle 2) of the slit sections to the total length of the electrode can be 3% to 32%. Also, the ratio of the length of the electrode region corresponding to the height uniform section (circle 3) of the slit sections to the total length of the electrode can be 59% to 87%.

[0292] On the other hand, the parameters described through Tables 4 to 6 are the radius of the core (a); the radius of the electrode assembly (b); the minimum height h 1 and the maximum height h N; The change amount Δh of the height of the sub-slice per 1 mm increase in radius; It can vary depending on design factors including the thicknesses of the positive electrode, negative electrode, and separator.

[0293] Therefore, the number of sub-slice layers in the number-average interval of sub-slice layers can be extended from 10 to 35. The ratio (d / f) of the height variable interval (circle 2) of the sub-slice can be extended to 1% - 50%. Also, the ratio (e / f) of the number-average interval of layers can be extended to 30% - 85%. Also, the ratio of the length of the sub-slice omission interval (circle 1) to the radius of the electrode assembly excluding the core (c / (b - a)) can be extended to 10% - 40%. Also, the ratio of the length of the electrode region corresponding to the sub-slice omission interval (circle 1) to the total length of the electrode (length in the winding direction) can be extended to 1% - 30%. Also, the ratio of the length of the electrode region corresponding to the height variable interval (circle 2) of the sub-slice to the total length of the electrode can be extended to 1% - 40%. Also, the ratio of the length of the electrode region corresponding to the height uniform interval (circle 3) of the sub-slice to the total length of the electrode can be extended to 50% - 90%. In the above-described embodiments, the maximum height h of the sub-slices included in the height variable interval (circle 2) and the height uniform interval (circle 3) N The height index N is 2 - 8. For example, referring to Table 4, the height indices N for Example 1-1 and Example 1-7 are 2 and 8 respectively. However, the height index N can vary depending on the change amount Δh of the height of the sub-slice in the radial direction of the electrode assembly. When the radial length of the height variable interval (circle 2) is fixed, as the change amount Δh of the height of the sub-slice decreases, the height index N increases accordingly, and vice versa is also possible. Preferably, the height index N is 2 - 20, and optionally, it can be further extended up to 2 - 30.

[0294] In the bent surface region F formed at the upper and lower parts of the electrode assembly, the number-average interval of layers can be used as the welding target region of the current collector.

[0295] Preferably, the welding region of the current collector preferably overlaps with the number-average interval of layers in the radial direction of the electrode assembly by at least 50%, and the higher the overlapping ratio, the more preferable.

[0296] Preferably, other regions of the welding region of the current collector that do not overlap with the uniform lamination number region may overlap with a lamination number decreasing region adjacent to the uniform lamination number region in the radial direction.

[0297] More preferably, other regions of the welding region of the current collector that do not overlap with the uniform lamination number region may overlap with a region where the number of overlapping segments in the lamination number decreasing region is 10 or more.

[0298] Welding the current collector to a region where the number of laminations of the segments is 10 or more is preferable in terms of welding strength and preventing damage to the separator film and the active material layer during welding. In particular, it is useful when welding the current collector using a high-output laser with high transmission characteristics.

[0299] If the uniform lamination number region where 10 or more segments are laminated and the current collector are welded by laser, even if the output of the laser is increased to improve the welding quality, since the uniform lamination number region mostly absorbs the energy of the laser to form a weld bead, it is possible to prevent the phenomenon that the separator film and the active material layer below the bent surface region F are damaged by the laser.

[0300] Also, since the number of laminations of the segments in the region irradiated with the laser is 10 or more, a weld bead is formed with sufficient volume and thickness. Therefore, the welding strength is sufficiently ensured, and the resistance of the welding interface can be lowered to a level suitable for rapid charging.

[0301] The output of the laser during welding of the current collector can be determined by the desired welding strength between the bent surface region F and the current collector. The welding strength increases in proportion to the number of laminations of the segments. This is because as the number of laminations increases, the volume of the weld bead formed by the laser becomes larger. The weld bead is formed while the material of the current collector and the material of the segments are melted together. Therefore, when the volume of the weld bead is large, the current collector and the bent surface region are more strongly bonded, and the contact resistance of the welding interface becomes lower.

[0302] Preferably, the welding strength is 2 kgf / cm 2 or more, more preferably 4 kgf / cm 2 or more. The maximum welding strength can vary according to the output of the laser welding apparatus. As an example, the welding strength is preferably 8 kgf / cm 2 or less, more preferably 6 kgf / cm 2 or less. However, the present invention is not limited thereto.

[0303] When the welding strength satisfies the above numerical range, even if intense vibration is applied to the electrode assembly along the winding axis direction and / or the radial direction, the physical properties of the welding interface do not deteriorate, and since the volume of the welding bead is sufficient, the resistance of the welding interface can also be reduced.

[0304] The output of the laser for satisfying the conditions of the welding strength varies depending on the laser apparatus, but can be appropriately adjusted in the range of 250 W to 320 W or in the range of 40% to 100% of the maximum laser output specification provided by the corresponding apparatus.

[0305] The welding strength can be defined as the tensile force per unit area (kgf / cm 2 ) of the current collector when the current collector begins to separate from the bent surface region F. Specifically, after the welding of the current collector is completed, a tensile force is applied to the current collector and its magnitude is gradually increased. When the tensile force exceeds the critical value, the segmented piece begins to separate from the welding interface. At this time, the value obtained by dividing the tensile force applied to the current collector by the area of the current collector corresponds to the welding strength.

[0306] In the bent surface region F, the segmented pieces are laminated in a plurality of layers, and according to the above-described embodiment, the number of laminated segmented pieces can increase from a minimum of 10 to a maximum of 35.

[0307] The thickness of the positive current collector (foil) constituting the non-patterned portion 43 is 10 μm to 25 μm, and the thickness of the negative current collector (foil) constituting the non-patterned portion 43 can be 5 μm to 20 μm. Therefore, the bent surface region F of the positive electrode can include a region where the total laminated thickness of the segmented pieces is 100 μm to 875 μm. Also, the bent surface region F of the negative electrode can include a region where the total laminated thickness of the segmented pieces is 50 μm to 700 μm.

[0308] FIG. 12 is a top view of an electrode assembly showing a uniform lamination number interval b1 and a decreasing lamination number interval b2 in the bent surface region F of the segmented pieces 61, 61' according to an embodiment of the present invention.

[0309] Referring to FIG. 12, the region between the two circles shown by the thick solid line corresponds to the bent surface region F of the segmented piece, the region between the two circles shown by the one-dot chain line corresponds to the uniform lamination number interval b1 where the lamination number of the segmented piece is 10 or more, and the outer region of the uniform lamination number interval b1 corresponds to the decreasing lamination number interval b2.

[0310] As an example, if the current collector P c is welded to the bent surface region F, a welding pattern W c is generated on the surface of the current collector P. The welding pattern W p can be an array of line patterns or dot patterns. The welding pattern W p corresponds to the welding region and can overlap with the uniform lamination number interval b1 of the segmented piece by 50% or more along the radial direction. Therefore, a part of the welding pattern W p is included in the uniform lamination number interval b1, and the remaining welding pattern W p can be included in the decreasing lamination number interval b2 outside the uniform lamination number interval b1. Of course, in order to maximize the welding strength and reduce the resistance of the welding region, the entire welding pattern W p can overlap with the uniform lamination number interval b1. p The whole can overlap with the uniform lamination number interval b1.

[0311] The area of the bent surface region F can be defined as the sum of the area of the average number of stacked layers section b1 and the area of the decreasing number of stacked layers section b2 of the segmented slice. Since the ratio (e / f) of the average number of stacked layers section b1 is 30% to 85%, preferably 31% to 82%, the ratio of the area of the average number of stacked layers section b1 to the area of the bent surface region F is 9% (30 2 / 100 2 ) to 72% (85 2 / 100 2 ), preferably 10% (31 2 / 100 2 ) to 67% (82 2 / 100 2 ).

[0312] Preferably, the end of the portion where the current collector P c contacts the bent surface region F can cover the ends of the segmented slices 61, 61' bent toward the core C side at the last winding turn of the height uniform section (round 3). In this case, with the segmented slices 61, 61' pressed by the current collector P c , a welding pattern W p is formed, so that the current collector P c and the bent surface region F are strongly bonded. As a result, the segmented slices 61, 61' stacked in the winding axis direction are closely adhered to each other, so that the resistance at the welding interface is also reduced, and the phenomenon of the segmented slices 61, 61' floating up can be prevented.

[0313] On the other hand, the bending direction of the segmented slice may be opposite to the above-described direction. That is, the segmented slice may be bent from the core side to the outer peripheral side. In this case, the pattern in which the height of the segmented slice changes along the winding direction (X-axis direction) may be opposite to the above-described embodiment (modified example). For example, the height of the segmented slice may gradually decrease from the core to the outer peripheral side. Also, the structure applied to the first portion B1 and the structure applied to the second portion B3 may be substituted for each other. Preferably, the height of the segmented slice is gradually decreased from the core side to the outer peripheral side, and when the segmented slice closest to the outer periphery of the electrode assembly is bent to the outer peripheral side, the height change pattern of the segmented slice is designed so that the end of the segmented slice does not protrude outside the outer periphery of the electrode assembly.

[0314] The electrode structure of the above-described embodiment (modification) can be applied to at least one of the first electrode and the second electrode having different polarities included in a jelly roll type or other types of electrode assemblies well-known in the art. Further, when the electrode structure of the embodiment (modification) is applied to one of the first electrode and the second electrode, a conventional electrode structure can be applied to the other. Further, the electrode structures applied to the first electrode and the second electrode may not be the same and may be different.

[0315] As an example, when the first electrode and the second electrode are a positive electrode and a negative electrode, respectively, any one of the embodiments (modifications) can be applied to the first electrode, and a conventional electrode structure (see FIG. 1) can be applied to the second electrode.

[0316] As another example, when the first electrode and the second electrode are a positive electrode and a negative electrode, respectively, any one of the embodiments (modifications) can be selectively applied to the first electrode, and another one of the embodiments (modifications) can be selectively applied to the second electrode.

[0317] In one embodiment of the present invention, the positive electrode active material coated on the positive electrode and the negative electrode active material coated on the negative electrode can be used without limitation as long as they are active materials known in the art.

[0318] As an example, the positive electrode active material may include an alkali metal compound represented by the general chemical formula A[A x M y O 2+z (A includes at least one element of Li, Na, and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≧0, 1≦x + y≦2, -0.1≦z≦2; the stoichiometric coefficients x, y, and z are selected so that the compound maintains electrical neutrality).

[0319] As another example, the positive electrode active material is an alkali metal compound xLiM disclosed in U.S. Patent No. 6,677,082, U.S. Patent No. 6,680,143, etc. 1 O 2-(1-x)Li 2 M 2 O 3 (M 1 contains at least one element having an average oxidation state of 3; M 2 contains at least one element having an average oxidation state of 4; 0 ≦ x ≦ 1).

[0320] As another example, the positive electrode active material has the general chemical formula Li a M 1 x Fe 1-x M 2 y P 1-y M 3 z O 4-z (M 1 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, and Al; M 2 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V, and S; M 3 contains a halogen group element selectively containing F; 0 < a ≦ 2, 0 ≦ x ≦ 1, 0 ≦ y < 1, 0 ≦ z < 1; the stoichiometric coefficients a, x, y, and z are selected so that the compound maintains electrical neutrality), or Li 3 M 2 (PO 4 ) 3 [M contains at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and Al] and can be a lithium metal phosphate represented by.

[0321] Preferably, the positive electrode active material may contain primary particles and / or secondary particles formed by aggregation of primary particles.

[0322] As an example, as the negative electrode active material, a carbon material, a lithium metal or a lithium metal compound, silicon or a silicon compound, tin or a tin compound, etc. can be used. TiO 2 where the potential is less than 2V, SnO 2Metal oxides such as this can also be used as the negative electrode active material. As the carbon material, any of low-crystalline carbon, high-crystalline carbon, etc. can be used.

[0323] As the separation membrane, a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as a homopolymer of ethylene, a homopolymer of propylene, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., can be used alone or these can be laminated and used. As another example, the separation membrane can use a normal porous non-woven fabric, for example, a non-woven fabric made of high-melting glass fibers, polyethylene terephthalate fibers, etc.

[0324] At least one surface of the separation membrane may include a coating layer of inorganic particles. Also, the separation membrane itself may consist of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound to a binder so that an interstitial volume exists between adjacent particles.

[0325] The inorganic particles can be made of an inorganic substance having a dielectric constant of 5 or more. As a non-limiting example, the inorganic particles are Pb(Zr,Ti)O 3 (PZT), Pb 1-x La x ZR 1-y Ti y O 3 (PLZT), PB(Mg 3 Nb 2 / 3 )O 3 -PbTiO 3 (PMN-PT), BaTiO 3 , hafnia (HfO 2 ), SrTiO 3 , TiO 2 , Al 2 O 3 , ZrO 2 , SnO 2 , CeO 2 , MgO, CaO, ZnO and Y 2 O 3 and may contain at least one substance selected from the group consisting of.

[0326] Hereinafter, the structure of the electrode assembly according to an embodiment of the present invention will be described in detail.

[0327] FIG. 13 is a cross-sectional view of a jelly roll type electrode assembly 100 in which the electrode 60 of the embodiment is applied to the first electrode (positive electrode) and the second electrode (negative electrode), cut along the Y-axis direction (winding axis direction).

[0328] Referring to FIG. 13, the plain portion 43a of the first electrode includes a first portion B1 adjacent to the core of the electrode assembly 100, a second portion B3 adjacent to the outer peripheral surface of the electrode assembly 100, and a third portion B2 interposed between the first portion B1 and the second portion B3.

[0329] The height of the plain portion of the first portion B1 is relatively lower than the height of the segment 61. Also, the height of the first portion B1 is lower than the height of the plain portion at the lower end of the cutting groove between the segments. Also, in the third portion B2, the bending length of the innermost segment 61 is the same as or shorter than the radial length R of the first portion B1. The bending length H corresponds to the distance from the point where the innermost segment 61 is bent to the upper end of the segment 61. In a modified example, the bending length H can be smaller than the value obtained by adding the radial length R of the winding turn formed by the first portion B1 and 10% of the radius of the core 102.

[0330] Therefore, even when the segment 61 is bent, 90% or more of the diameter of the core 102 of the electrode assembly 100 is open to the outside. The core 102 is a cavity at the center of the electrode assembly 100. If the core 102 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Also, a welding jig can be inserted through the core 102 to easily perform the welding process between the current collector plate on the negative electrode (or positive electrode) side and the battery housing (or rivet terminal).

[0331] The height of the non-patterned portion of the second part B3 is relatively lower than the height of the segmented piece 61. Therefore, in the process of the beading portion of the battery housing being pressed near the winding turn of the second part B3, it is possible to prevent the phenomenon of internal short circuit while the beading portion and the upper end periphery of the electrode assembly 100 are in contact. Optionally, the height of the second part B3 can be lower than the height of the non-patterned portion at the lower end of the cutting groove between the segmented pieces.

[0332] In a modification, the second part B3 may include the segmented piece 61, and the height of the segmented piece 61 of the second part B3 may decrease gradually or stepwise, different from the illustration in FIG. 13. Also, in FIG. 13, although the height of the segmented piece 61 is equal in a part on the outer peripheral side, the height of the segmented piece 61 may increase gradually or stepwise from the boundary between the first part B1 and the third part B2 to the boundary between the third part B2 and the second part B3. The section where the height of the segmented piece 61 changes corresponds to the height variable section of the segmented piece (circle 2 in FIG. 10a).

[0333] The second non-patterned portion 43b has the same structure as the first non-patterned portion 43a. In a modification, the second non-patterned portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (modifications).

[0334] The end portion 101 of the segmented piece 61 can be bent from the radial direction of the electrode assembly 100, for example, from the outer peripheral side to the core side. At this time, the non-patterned portions of the first part B1 and the second part B3 are not substantially bent. Also, the height of the first part B1 is lower than the height of the non-patterned portion at the lower part of the cutting groove between the segmented pieces. Therefore, when the segmented piece 61 is bent, it is possible to prevent the non-patterned portion of the first part B1 from being deformed.

[0335] Since the third part B2 includes a plurality of segments 61 arranged radially, bending stress can be relaxed to prevent the plain portions 43a and 43b near the bending point from being torn or abnormally deformed. Further, when the width and / or height and / or separation pitch of the segments 61 are adjusted within the numerical range of the above-described embodiments, the segments 61 are overlapped multiple times to ensure sufficient welding strength while being bent toward the core side, and no space (gap) is formed in the bent surface region F.

[0336] FIG. 14 is a cross-sectional view of an electrode assembly 110 according to still another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0337] Referring to FIG. 14, the electrode assembly 110 includes segments 61 also in the second part B3, and other configurations are substantially the same as those of the electrode assembly 100 in FIG. 13, except that the height of the segments 61 in the second part B3 is substantially the same as the height of the outermost segments 61 in the third part B2.

[0338] In the electrode assembly 110, the height of the plain portion in the first part B1 is relatively lower than the height of the segments 61 included in the third part B2. Also, the bending length H of the innermost segments 61 in the third part B2 is the same as or shorter than the radial length R of the winding turn formed by the first part B1. Preferably, the winding turn formed by the first part B1 may be a segment omission section (circle 1 in FIG. 10a) without segments. In a modified example, the bending length H may be smaller than the value obtained by adding the radial length R of the winding turn formed by the first part B1 and 10% of the radius of the core 112.

[0339] Therefore, even when the segments 61 included in the third part B2 are bent, 90% or more of the diameter of the core 112 of the electrode assembly 110 is opened to the outside. If the core 112 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Further, a welding jig can be inserted through the core 112 to easily perform a welding process between the current collector plate on the negative electrode (or positive electrode) side and the battery housing (or rivet terminal).

[0340] In a modified example, the structure in which the height of the segmented piece 61 included in the third portion B2 gradually or stepwise increases from the core side toward the outer peripheral side can be extended to the winding turns formed by the second portion B3. In this case, the height of the segmented piece 61 can gradually or stepwise increase from the boundary between the first portion B1 and the third portion B2 to the outermost surface of the electrode assembly 110.

[0341] The second non-textured portion 43b has the same structure as the first non-textured portion 43a. In a modified example, the second non-textured portion 43b can have a conventional electrode structure or an electrode structure of other embodiments (modified examples).

[0342] The end portion 111 of the segmented piece 61 included in the third portion B2 can be bent from the radial direction of the electrode assembly 110, for example, from the outer peripheral side toward the core side. At this time, the non-textured portion of the first portion B1 is not substantially bent.

[0343] Since the third portion B2 includes a plurality of segmented pieces 61 arranged in the radial direction, it is possible to prevent the bending stress from being relaxed and the non-textured portions 43a and 43b near the bending point from being torn or abnormally deformed. Further, when the width and / or height and / or separation pitch of the segmented piece 61 are adjusted within the numerical range of the above-described embodiment, the segmented pieces 61 are folded toward the core side while overlapping multiple times to such an extent that sufficient welding strength can be ensured, and no space (gap) is formed in the bent surface region.

[0344] FIG. 15 is a cross-sectional view of an electrode assembly 120 according to still another embodiment of the present invention, cut along the Y-axis direction (winding axis direction).

[0345] Referring to FIG. 15, the electrode assembly 120 has substantially the same configuration as the electrode assembly 100 in FIG. 13, except that the height of the segmented piece 61 included in the third portion B2 has a pattern of gradually or stepwise increasing and then decreasing. The radius interval in which the height of the segmented piece 61 changes can be regarded as the height variable interval of the segmented piece (circle 2 in FIG. 10a). Also in this case, the height variable interval of the segmented piece 61 can be designed such that in the bending surface region F formed while the segmented piece 61 is bent, the number-of-layers uniform interval in which the number of layers of the segmented piece 61 is 10 or more appears within the above-described preferable numerical range.

[0346] In the electrode assembly 120, the height of the plain portion of the first portion B1 is relatively lower than the height of the segmented piece 61. Also, the bending length H of the segmented piece 61 closest to the core 122 is the same as or shorter than the radial length R of the winding turn formed by the first portion B1. The interval corresponding to the winding turn formed by the first portion B1 corresponds to the segmented-piece omission interval (circle 1 in FIG. 10a) where there is no segmented piece. In a modified example, the bending length H can be made smaller than the value obtained by adding the radial length R of the winding turn formed by the first portion B1 and 10% of the radius of the core 102.

[0347] Therefore, even if the segmented piece 61 included in the third portion B2 is bent toward the core side, 90% or more of the diameter of the core 122 of the electrode assembly 120 is open to the outside. If the core 122 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Also, a welding jig can be inserted through the core 122, and the welding process between the current collector plate on the negative electrode (or positive electrode) side and the battery housing (or rivet terminal) can be easily performed.

[0348] Further, the height of the non-patterned portion of the second portion B3 is relatively lower than the height of the segment 61, and preferably, the segment 61 may not be formed in the second portion B3. Therefore, in the process of the beading portion of the battery housing being pressed in the vicinity of the winding turn formed by the second portion B3, it is possible to prevent the phenomenon of internal short circuit occurring while the beading portion and the periphery of the electrode assembly 120 come into contact with each other. In a modified example, the second portion B3 may include a segment, and the height of the segment of the second portion B3 may gradually or stepwise decrease toward the outer peripheral side.

[0349] The second non-patterned portion 43b has the same structure as the first non-patterned portion 43a. In a modified example, the second non-patterned portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (modified examples).

[0350] The end portion 121 of the segment 61 included in the third portion B2 can be bent from the outer peripheral side to the core side of the electrode assembly 120. At this time, the non-patterned portions of the first portion B1 and the second portion B3 are not substantially bent.

[0351] Since the third portion B2 includes a plurality of segments 61 arranged in the radial direction, it is possible to prevent the bending stress from being relaxed and the non-patterned portions 43a and 43b from being torn or abnormally deformed. Further, when the width and / or height and / or separation pitch of the segment 61 are adjusted within the numerical range of the above-described embodiment, the segments 61 are bent toward the core side and overlap multiple times to ensure sufficient welding strength, and do not form a space (gap) in the bent surface region F.

[0352] FIG. 16 is a cross-sectional view of an electrode assembly 130 according to still another embodiment of the present invention, cut along the Y-axis direction (winding axis direction).

[0353] Referring to FIG. 16, the electrode assembly 130 includes segments 61 in the second portion B3 as compared with the electrode assembly 120 of FIG. 15, and the other configurations are substantially the same except that the height of the segments 61 has a pattern of gradually or stepwise decreasing from the boundary point between the second portion B3 and the third portion B2 toward the outermost surface of the electrode assembly 130.

[0354] In the electrode assembly 130, the height of the plain portion of the first portion B1 is relatively lower than the height of the segment 61. Also, the bending length H of the segment 61 closest to the core 132 is the same as or shorter than the radial length R of the winding turn formed by the first portion B1. The winding turn formed by the first portion B1 corresponds to a segment omission section without segments (circle 1 in FIG. 10a). In a modified example, the bending length H can be smaller than the value obtained by adding the radial length R of the winding turn formed by the first portion B1 and 10% of the radius of the core 102.

[0355] Therefore, even if the segment 61 included in the third portion B2 is bent toward the core side, 90% or more of the diameter of the core 132 of the electrode assembly 130 is opened to the outside. If the core 132 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Also, a welding jig can be inserted through the core 132, and the welding process between the current collector plate on the negative electrode (or positive electrode) side and the battery housing (or rivet terminal) can be easily performed.

[0356] The second plain portion 43b has the same structure as the first plain portion 43a. In a modified example, the second plain portion 43b can have a conventional electrode structure or an electrode structure of other embodiments (modified examples).

[0357] The end portion 131 of the segment 61 included in the third portion B2 can be bent from the outer peripheral side to the core side of the electrode assembly 130. At this time, the plain portion of the first portion B1 is not substantially bent.

[0358] Since the third portion B2 includes a plurality of segments 61 arranged in the radial direction, the bending stress can be relaxed, and it is possible to prevent the plain portions 43a and 43b near the bending point from being torn or abnormally deformed. Also, when the width and / or height and / or separation pitch of the segment 61 are adjusted within the numerical range of the above-described embodiment, the segments 61 are overlapped multiple times to ensure sufficient welding strength while being bent toward the core side, and no space (gap) is formed in the bent surface region F.

[0359] On the one hand, in the above-described embodiments (modifications), the end portion of the segmented piece 61 included in the third portion B2 may be bent from the core side to the outer peripheral side. In this case, the winding turn formed by the second portion B3 is designed as a segmented piece omission section (circle 1 in FIG. 10a) without a segmented piece, and it is preferable that it is not bent to the outer peripheral side. Further, the radial width of the winding turn formed by the second portion B3 can be the same as or larger than the length at which the outermost segmented piece is bent. Thereby, when the outermost segmented piece is bent to the outer peripheral side, the end portion of the bending portion does not protrude beyond the outer peripheral surface of the electrode assembly toward the inner surface of the battery housing. Also, the structural change pattern of the segmented pieces included in the third portion B2 may be opposite to that of the above-described embodiments (modifications). For example, the height of the segmented pieces can gradually or gradually decrease from the core side to the outer peripheral side. That is, by arranging a segmented piece omission section (circle 1 in FIG. 10a), a segmented piece height variable section (circle 2 in FIG. 10a), and a segmented piece height uniform section (circle 3 in FIG. 10) in order from the outer peripheral side to the core side of the electrode assembly, a stacked number uniform section in which the number of stacked segmented pieces in the bending surface region F is 10 or more may appear within a preferable numerical range.

[0360] The structures of various electrode assemblies according to the embodiments of the present invention can be applied to jelly roll type cylindrical batteries.

[0361] Preferably, the cylindrical battery can be, for example, a cylindrical battery having a form factor ratio (a value obtained by dividing the diameter of the cylindrical battery by the height, that is, a ratio of the height (H) to the diameter (Φ)) greater than about 0.4. Here, the form factor means a value indicating the diameter and height of the cylindrical battery.

[0362] Preferably, the diameter of the cylindrical battery is 35 mm or more, preferably 40 mm to 50 mm. The height of the cylindrical battery can be 70 mm or more, preferably 75 mm to 90 mm. The cylindrical battery according to an embodiment can be, for example, 46110 battery, 4875 battery, 48110 battery, 4880 battery, 4680 battery. In the numerical value indicating the form factor, the first two digits indicate the diameter of the battery, and the remaining digits indicate the height of the battery.

[0363] When applying an electrode assembly having a tabless structure to a cylindrical battery with a form factor ratio exceeding 0.4, the stress applied in the radial direction during bending of the plain part is large, and the plain part is likely to break. Also, when welding a current collector plate to the bent surface area of the plain part, in order to sufficiently ensure the welding strength and reduce the resistance, the number of laminations of the plain part in the bent surface area must be sufficiently increased. Such requirements can be achieved by the electrodes and electrode assemblies according to the embodiments (modifications) of the present invention.

[0364] The battery according to an embodiment of the present invention can be a substantially cylindrical battery having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0365] The battery according to another embodiment can be a substantially cylindrical battery having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of 0.640.

[0366] The battery according to still another embodiment can be a substantially cylindrical battery having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.436.

[0367] The battery according to still another embodiment can be a substantially cylindrical battery having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0368] Batteries according to still other embodiments may be substantially cylindrical batteries, which may be cylindrical batteries having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0369] Conventionally, batteries having a form factor ratio of about 0.4 or less have been used. That is, conventionally, for example, 1865 batteries, 2170 batteries, etc. have been used. In the case of 1865 batteries, the diameter is about 18 mm, the height is about 65 mm, and the form factor ratio is 0.277. In the case of 2170 batteries, the diameter is about 21 mm, the height is about 70 mm, and the form factor ratio is 0.300.

[0370] Hereinafter, the cylindrical battery according to the embodiment of the present invention will be described in detail.

[0371] FIG. 17 is a cross-sectional view of a cylindrical battery 190 according to an embodiment of the present invention cut along the Y-axis direction.

[0372] Referring to FIG. 17, a cylindrical battery 190 according to an embodiment of the present invention includes an electrode assembly 110 including a first electrode, a separator, and a second electrode, a battery housing 142 for housing the electrode assembly 110, and a sealing body 143 for sealing the open end of the battery housing 142.

[0373] The battery housing 142 is a cylindrical container having an opening formed upward. The battery housing 142 is made of a conductive metal material such as aluminum, steel, or stainless steel. A nickel coating layer may be formed on the surface of the battery housing 142. The battery housing 142 houses the electrode assembly 110 in the inner space through the upper end opening, and also houses the electrolyte together.

[0374] The electrolyte may be a salt having a structure such as A + B - . Here, A + is Li + , Na+ and contains ions consisting of alkali metal cations such as K + or combinations thereof. And B - is F - ,Cl - ,Br - ,I - ,NO 3 - ,N(CN) 2 - ,BF 4 - ,ClO 4 - ,AlO 4 - ,AlCl 4 - ,PF 6 - ,SbF 6 - ,AsF 6 - ,BF 2 C 2 O 4 - ,BC 4 O 8 - ,(CF 3 ) 2 PF 4 - ,(CF 3 ) 3 PF 3 - ,(CF 3 ) 4 PF 2 - ,(CF 3 ) 5 PF - ,(CF 3 ) 6 P - ,CF 3 SO 3 - ,C 4 F 9 SO 3 - ,CF 3 CF 2 SO 3 - ,(CF 3 SO 2 ) 2 N -, (FSO 2 ) 2 N - , CF 3 CF 2 (CF 3 ) 2 CO - , (CF 3 SO 2 ) 2 CH - , (SF 5 ) 3 C - , (CF 3 SO 2 ) 3 C - , CF 3 (CF 2 ) 7 SO 3 - , CF 3 CO 2 - , CH 3 CO 2 - , SCN - and (CF 3 CF 2 SO 2 ) 2 N - contains any one or more anions selected from the group consisting of.

[0375] Also, the electrolyte can be used by dissolving it in an organic solvent. As the organic solvent, propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or a mixture thereof can be used.

[0376] The electrode assembly 110 can have a jelly-roll structure. As shown in FIG. 2, the electrode assembly 110 can be manufactured by winding a laminate formed by laminating at least once in order a lower separator, a first electrode, an upper separator, and a second electrode around a winding center C.

[0377] The first electrode and the second electrode have different polarities. That is, if one has a positive polarity, the other has a negative polarity. At least one of the first electrode and the second electrode may have the electrode structure according to the above-described embodiments (modifications). Further, the other of the first electrode and the second electrode may have a conventional electrode structure or an electrode structure according to an embodiment (modification). The number of electrode pairs included in the electrode assembly 110 is not limited to one, and may be two or more.

[0378] The segmented pieces included in the third portion B2 form a bent surface region F while being bent from the radial direction of the electrode assembly 110, for example, from the outer peripheral side to the core side.

[0379] The first portion B1 is lower in height than the other portions and corresponds to the segment omission section a1 without segmented pieces, and thus is not bent toward the core side. The height of the plain portion of the first portion B1 may be lower than the plain portion at the lower part of the cutting groove between the segmented pieces.

[0380] Preferably, the bent surface region F may include, in order from the core side to the outer peripheral side, a segment omission section a1, a segment height variable section a2, and a segment height uniform section a3.

[0381] As shown in FIGS. 11a, 11b, and 11c, the bent surface region F includes a layer number uniform section b1 adjacent to the segment omission section a1 and having 10 or more layers of stacked segmented pieces.

[0382] The bent surface region F may also include a layer number decreasing section b2 adjacent to the outer periphery of the electrode assembly 110 and having the number of stacked segmented pieces decreasing toward the outer peripheral side. Preferably, the layer number uniform section b1 may be set as a welding target region.

[0383] In the bent surface region F, the ratio (a2 / c) of the height variable range a2 of the segment pieces based on the radial length (c) where the segment pieces exist, the ratio (b1 / c) of the layer number average region b1 of the segment pieces, and the preferable numerical range of the ratio of the area of the layer number average region b1 to the area of the bent surface region F have been described above, so repeated explanations are omitted.

[0384] The first current collector plate 144 can be laser welded to the bent surface region F of the first plain portion 146a, and the second current collector plate 145 can be laser welded to the bent surface region F of the second plain portion 146b. The welding method can be replaced with ultrasonic welding, resistance welding, spot welding, etc.

[0385] Preferably, 50% or more of the region of the welding region W of the first current collector plate 144 and the second current collector 145 can overlap with the layer number average region b1 of the bent surface region F. Optionally, the remaining region of the welding region W can overlap with the layer number decreasing region b2 of the bent surface region F. In terms of high welding strength, low resistance at the welding interface, and prevention of damage to the separator membrane and the active material layer, it is more preferable that the entire welding region W overlaps with the layer number average region b1.

[0386] Preferably, in the layer number average region b1 overlapping with the welding region W and optionally in the layer number decreasing region b2, the layer number of the segment pieces can be 10 to 35.

[0387] Optionally, when the layer number of the segment pieces in the layer number decreasing region b2 overlapping with the welding region W is less than 10, the laser output of the layer number decreasing region b2 can be reduced compared to the laser output of the layer number average region b1. That is, when the welding region W overlaps with both the layer number average region b1 and the layer number decreasing region b2, the output of the laser can be changed according to the layer number of the segment pieces. In this case, the welding strength of the layer number average region b1 can be greater than the welding strength of the layer number decreasing region b2.

[0388] In the bent surface regions F formed on the upper and lower portions of the electrode assembly 110, the radial lengths of the segment omission intervals a1 and / or the segment height variable intervals a2 and / or the segment height uniform intervals a3 may be the same or different.

[0389] Also, the bent surface regions F formed on the upper and lower portions of the electrode assembly 110 may form a plane-symmetric structure. Therefore, when the upper bent surface region F is projected onto the lower bent surface region F, they may substantially overlap each other.

[0390] In the electrode assembly 110, the height of the plain portion of the first portion B1 is relatively lower than that of the other portions. Also, as shown in FIG. 14, the bending length H of the segment closest to the core is smaller than the value obtained by adding the radial length R of the winding turn formed by the first portion B1 and 10% of the radius of the core 112.

[0391] Therefore, even if the segments included in the third portion B2 are bent toward the core side, 90% or more of the diameter of the core 112 of the electrode assembly 110 can be opened to the outside. If the core 112 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Also, a welding jig can be inserted through the core 112 to easily perform the welding process between the second current collector plate 145 and the battery housing 142.

[0392] When the width and / or height and / or separation pitch of the segments are adjusted to satisfy the numerical ranges of the above-described embodiments, when the segments are bent, the segments overlap multiple times to such an extent that sufficient welding strength can be ensured, and no space (gap) is formed in the bent surface region F.

[0393] Preferably, the first current collector 144 and the second current collector 145 may have an outer diameter that covers the ends of the cut pieces (see 61 in FIG. 12) bent at the last winding turns of the first electrode and the second electrode. In this case, welding is possible with the cut pieces forming the bent surface region F being uniformly pressed by the current collectors, and the tight stacked state of the cut pieces can be maintained even after welding. The tight stacked state means a state where there is substantially no gap between the cut pieces, as shown in FIG. 10a. The tight stacked state contributes to reducing the resistance of the cylindrical battery 190 to a level suitable for rapid charging (e.g., 4 mΩ) or less.

[0394] The sealing body 143 may include a cap plate 143a, a first gasket 143b that provides airtightness and has insulation between the cap plate 143a and the battery housing 142, and a connection plate 143c electrically and mechanically coupled to the cap plate 143a.

[0395] The cap plate 143a is a component made of a conductive metal material and covers the upper end opening of the battery housing 142. The cap plate 143a is electrically connected to the bent surface region F of the first electrode and is electrically insulated from the battery housing 142 through the first gasket 143b. Therefore, the cap plate 143a can function as the first electrode terminal (e.g., the positive electrode) of the cylindrical battery 190.

[0396] The cap plate 143a is placed on the beading portion 147 formed on the battery housing 142 and fixed by the crimping portion (148). A first gasket 143b may be interposed between the cap plate 143a and the crimping portion 148 for ensuring the airtightness of the battery housing 142 and the electrical insulation between the battery housing 142 and the cap plate 143a. The cap plate 143a may include a protruding portion 143d formed to protrude upward from its central portion.

[0397] The battery housing 142 is electrically connected to the bent surface region F of the second electrode. Therefore, the battery housing 142 has the same polarity as the second electrode. If the second electrode has a negative polarity, the battery housing 142 also has a negative polarity.

[0398] The battery housing 142 includes a beading portion 147 and a crimping portion 148 at the upper end. The beading portion 147 is formed by pushing it in around the outer peripheral surface of the battery housing 142. The beading portion 147 can function as a support portion on which the sealing body 143 is placed so that the electrode assembly 110 housed inside the battery housing 142 does not come out from the upper end opening of the battery housing 142.

[0399] The second portion B3 of the first electrode does not include a segmented piece and can be notched with the same structure as the first portion B1. Preferably, the inner peripheral surface of the beading portion 147 is separated from the winding turn formed by the second portion B3 of the first electrode by a predetermined interval. This is because the second portion B3 is notched like the first portion B1. More specifically, the lower end of the inner peripheral surface of the beading portion 147 is separated from the winding turn formed by the second portion B3 of the first electrode by a predetermined interval. Also, since the plain portion of the second portion B3 has a low height, the winding turn of the second portion B3 is not substantially affected even when the battery housing 142 is pushed in from the outside to form the beading portion 147. Therefore, the winding turn of the second portion B3 is not pressed by other components such as the beading portion 147, thereby preventing the occurrence of partial deformation of the electrode assembly 110 and preventing an internal short circuit of the cylindrical battery 190.

[0400] Preferably, if the pushing depth of the beading portion 147 is D1 and the radial length from the inner peripheral surface of the battery housing 142 to the boundary point between the second portion B3 and the third portion B2 is D2, the relational expression D1 ≤ D2 can be satisfied. In this case, when the battery housing 142 is pushed in to form the beading portion 147, damage to the winding turn formed by the second portion B3 is substantially prevented.

[0401] The crimping portion 148 is formed on the upper part of the beading portion 147. The crimping portion 148 has a form that extends and is bent so as to wrap the outer peripheral surface of the cap plate 143a disposed on the beading portion 147 and a part of the upper surface of the cap plate 143a.

[0402] The cylindrical battery 190 may further include the first current collector 144 and / or the second current collector 145 and / or the insulator 146.

[0403] The first current collector 144 is coupled to the upper part of the electrode assembly 110. The first current collector 144 is made of a metallic material having conductivity such as aluminum, copper, steel, nickel, etc., and is electrically connected to the bent surface region F of the first electrode. The electrical connection can be made through welding. A lead 149 may be connected to the first current collector 144. The lead 149 may extend above the electrode assembly 110 and be coupled to the connection plate 143c, or may be directly coupled to the lower surface of the cap plate 143a. The connection between the lead 149 and other components can be made through welding.

[0404] Preferably, the first current collector 144 may be integrally formed with the lead 149. In this case, the lead 149 may have a long plate shape extending outward from near the central portion of the first current collector 144.

[0405] The connection between the first current collector 144 and the bent surface region F of the first electrode can be made, for example, by laser welding. Laser welding can be performed in a manner that partially melts the base material of the current collector. In a modified example, the welding between the first current collector 144 and the bent surface region F can be performed with solder interposed therebetween. In this case, the solder may have a melting point lower than that of the first current collector 144 and the first plain portion 146a. Laser welding can be replaced by resistance welding, ultrasonic welding, spot welding, etc.

[0406] A second current collector plate 145 can be coupled to the lower surface of the electrode assembly 110. One surface of the second current collector plate 145 can be coupled to the bent surface region F of the second electrode by welding, and the other surface can be coupled to the inner bottom surface of the battery housing 142 by welding. The coupling structure between the second current collector plate 145 and the bent surface region F of the second electrode can be substantially the same as the coupling structure between the first current collector plate 144 and the bent surface region F of the first electrode.

[0407] The insulator 146 can cover the first current collector plate 144. By covering the first current collector plate 144 on the upper surface of the first current collector plate 144, direct contact between the first current collector plate 144 and the inner peripheral surface of the battery housing 142 can be prevented.

[0408] The insulator 146 is provided with a lead hole 151 so that a lead 149 extending upward from the first current collector plate 144 can be drawn out. The lead 149 is drawn upward through the lead hole 151 and coupled to the lower surface of the connection plate 143c or the lower surface of the cap plate 143a.

[0409] The peripheral region of the insulator 146 is interposed between the first current collector plate 144 and the beading portion 147, and can fix the combined body of the electrode assembly 110 and the first current collector plate 144. Thereby, the movement of the combined body of the electrode assembly 110 and the first current collector plate 144 in the height direction of the battery 140 is restricted, and the assembly stability of the battery 140 can be improved.

[0410] The insulator 146 can be made of an insulating polymer resin. As an example, the insulator 146 can be made of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0411] The battery housing 142 may further include a venting portion 152 formed on its lower surface. The venting portion 152 corresponds to a region having a thickness thinner than that of the peripheral region on the lower surface of the battery housing 142. The venting portion 152 is structurally weaker than the peripheral region. Therefore, if an abnormality occurs in the cylindrical battery 190 and the internal pressure increases above a certain level, the venting portion 152 may rupture and the gas generated inside the battery housing 142 may be discharged to the outside. The internal pressure at which the venting portion 152 ruptures may be about 15 kgf / cm 2 ~35 kgf / cm 2 It can be.

[0412] The venting portion 152 may be formed continuously or discontinuously while drawing a circle on the lower surface of the battery housing 142. As a modification, the venting portion 152 may be formed in a straight line pattern or other pattern other than that.

[0413] FIG. 18 is a cross-sectional view of a cylindrical battery 200 cut along the Y-axis direction according to another embodiment of the present invention.

[0414] Referring to FIG. 18, the cylindrical battery 200 is substantially the same in the structure of the electrode assembly as the cylindrical battery 190 shown in FIG. 17, and is different in that other structures except for the electrode assembly are changed.

[0415] Specifically, the cylindrical battery 200 includes a battery housing 171 through which a rivet terminal 172 is provided. The rivet terminal 172 is attached through a through hole formed in the closing surface (upper surface in the drawing) of the battery housing 171. The rivet terminal 172 is riveted to the through hole of the battery housing 171 with a second gasket 173 made of an insulating material interposed therebetween. The rivet terminal 172 is exposed outward in the direction opposite to the direction of gravity.

[0416] The rivet terminal 172 includes a terminal exposed portion 172a and a terminal insertion portion 172b. The terminal exposed portion 172a is exposed outside the closing surface of the battery housing 171. The terminal exposed portion 172a may be located at a substantially central portion of the closing surface of the battery housing 171. The maximum diameter of the terminal exposed portion 172a may be formed larger than the maximum diameter of the through hole formed in the battery housing 171. The terminal insertion portion 172b may penetrate through a substantially central portion of the closing surface of the battery housing 171 and be electrically connected to the plain portion 146a of the first electrode. The lower peripheral edge of the terminal insertion portion 172b may be rivet-coupled to the inner surface of the battery housing 171. That is, the lower peripheral edge of the terminal insertion portion 172b may have a form bent toward the inner surface of the battery housing 171. A flat portion 172c is included inside the lower peripheral edge of the terminal insertion portion 172b. The maximum diameter of the lower portion of the riveted terminal insertion portion 172b may be larger than the maximum diameter of the through hole of the battery housing 171.

[0417] The flat portion 172c of the terminal insertion portion 172b may be welded to the central portion of the first current collector plate 144 connected to the bent surface region F of the first electrode. As the welding method, laser welding is preferable, but other welding methods such as ultrasonic welding can be substituted.

[0418] An insulator 174 made of an insulating material may be interposed between the first current collector plate 144 and the inner surface of the battery housing 171. The insulator 174 covers the upper portion of the first current collector plate 144 and the upper end peripheral portion of the electrode assembly 110. Thereby, it is possible to prevent the second portion B3 of the electrode assembly 110 from contacting the inner surface of the battery housing 171 having an opposite polarity and causing a short circuit.

[0419] The thickness of the insulator 174 corresponds to or is slightly larger than the distance between the upper surface of the first current collector plate 144 and the inner surface of the closing portion of the battery housing 171. Therefore, the insulator 174 may contact the upper surface of the first current collector plate 144 and the inner surface of the closing portion of the battery housing 171.

[0420] The terminal insertion part 172b of the rivet terminal 172 can be welded to the first current collector plate 144 through the through hole of the insulator 174. The diameter of the through hole formed in the insulator 174 can be larger than the diameter of the riveting part at the lower end of the terminal insertion part 172b. Preferably, the through hole can expose the lower part of the terminal insertion part 172b and the second gasket 173.

[0421] The second gasket 173 is interposed between the battery housing 171 and the rivet terminal 172 to prevent the battery housing 171 and the rivet terminal 172 having opposite polarities from being in electrical contact. Thereby, the upper surface of the battery housing 171 having a substantially flat shape can function as the second electrode terminal (for example, the negative electrode) of the cylindrical battery 200.

[0422] The second gasket 173 includes a gasket exposed part 173a and a gasket insertion part 173b. The gasket exposed part 173a is interposed between the terminal exposed part 172a of the rivet terminal 172 and the battery housing 171. The gasket insertion part 173b is interposed between the terminal insertion part 172b of the rivet terminal 172 and the battery housing 171. The gasket insertion part 173b can be deformed together during the riveting of the terminal insertion part 172b and be in close contact with the inner surface of the battery housing 171. The second gasket 173 can be made of, for example, an insulating polymer resin.

[0423] The gasket exposed part 173a of the second gasket 173 can have a form extending so as to cover the outer peripheral surface of the terminal exposed part 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 in the process of connecting an electrical connection component such as a bus bar to the upper surface of the battery housing 171 and / or the rivet terminal 172. Although not shown, the gasket exposed part 173a may have a form extending so as to cover not only the outer peripheral surface of the terminal exposed part 172a but also a part of the upper surface.

[0424] When the second gasket 173 is made of a polymer resin, the second gasket 173 can be joined to the battery housing 171 and the rivet terminal 172 by heat fusion. In this case, the airtightness at the joint interface between the second gasket 173 and the rivet terminal 172 and at the joint interface between the second gasket 173 and the battery housing 171 is enhanced. On the other hand, when the gasket exposed portion 173a of the second gasket 173 has a form extending to the upper surface of the terminal exposed portion 172a, the rivet terminal 172 may be integrally joined to the second gasket 173 by insert injection molding.

[0425] On the upper surface of the battery housing 171, another region 175 excluding the regions 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.

[0426] The second current collector 176 is coupled to the lower portion of the electrode assembly 141. The second current collector 176 is made of a conductive metal material such as aluminum, steel, copper, nickel, etc., and is electrically connected to the bent surface region F of the second electrode.

[0427] Preferably, the second current collector 176 is electrically connected to the battery housing 171. Therefore, at least a part of the peripheral portion of the second current collector 176 can be interposed and fixed between the inner surface of the battery housing 171 and the first gasket 178b. As an example, at least a part of the peripheral portion of the second current collector 176 can be fixed to the beading portion 180 by welding while being supported by the lower end surface of the beading portion 180 formed at the lower end of the battery housing 171. In a modified example, at least a part of the peripheral portion of the second current collector 176 can be directly welded to the inner wall surface of the battery housing 171.

[0428] Preferably, the second current collector 176 and the bent surface region F of the second electrode can be joined, for example, by laser welding. Also, the welding site between the second current collector 176 and the bent surface region F is separated by a predetermined distance to the core C side with reference to the inner peripheral surface of the beading portion 180.

[0429] The sealing body 178 that seals the lower open end of the battery housing 171 includes a cap plate 178a and a first gasket 178b. The first gasket 178b electrically isolates the cap plate 178a and the battery housing 171. The crimping portion 181 fixes the peripheral edge 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 that of the above-described embodiment (modification). The lower surface of the cap plate 178a may be located above the lower end of the crimping portion 181. In this case, a space is formed below the cap plate 178a, and venting is performed smoothly. In particular, this is useful when the cylindrical battery 200 is installed such that the crimping portion 181 faces the direction of gravity.

[0430] Preferably, the cap plate 178a is made of a conductive metal material. However, since the first gasket 178b is interposed between the cap plate 178a and the battery housing 171, the cap plate 178a does not have an electric polarity. The sealing body 178 mainly functions to seal the lower open end of the battery housing 171 and discharge gas when the internal pressure of the battery 200 increases above a critical value. The critical value of the internal pressure is 15 kgf / cm 2 ~35 kgf / cm 2 is.

[0431] Preferably, the rivet terminal 172 electrically connected to the bent surface region F of the first electrode is used as the first electrode terminal. Also, a portion 175 of the upper surface of the battery housing 171, excluding the rivet terminal 172, that is electrically connected to the bent surface region F of the second electrode through the second current collector plate 176 is used as the second electrode terminal having a polarity opposite to that of the first electrode terminal. In this way, when the two electrode terminals are located at the upper part of the cylindrical battery 200, it is possible to arrange electrical connection components such as a bus bar only on one side of the cylindrical battery 200. This can lead to the simplification of the battery pack structure and the improvement of the energy density. Also, since the portion 175 used as the second electrode terminal has a substantially flat form, a sufficient bonding area for bonding electrical connection components such as a bus bar can be ensured. Thereby, the cylindrical battery 200 can reduce the resistance at the bonding site of the electrical connection components to a preferable level.

[0432] FIG. 19 is a cross-sectional view of a cylindrical battery 210 cut along the Y-axis direction according to still another embodiment of the present invention.

[0433] Referring to FIG. 19, the cylindrical battery 210 includes the electrode assembly 100 shown in FIG. 13, and other configurations excluding the electrode assembly 100 are substantially the same as those of the cylindrical battery 190 shown in FIG. 17. Therefore, the configurations described with reference to FIGS. 13 and 17 can be substantially similarly applied in this embodiment as well.

[0434] Preferably, the first non-coated portion 146a and the second non-coated portion 146b of the electrode assembly 100 include a plurality of divided sections 61. The divided sections 61 are bent from the radial direction of the electrode assembly 100, for example, from the outer peripheral side to the core side. At this time, the non-coated portions of the first part B1 and the second part B3 of the first non-coated portion 146a have a lower height than other portions and do not include divided sections, and thus are not substantially bent. The same applies to the second non-coated portion 146b.

[0435] Also in this embodiment, the bent surface region F formed by the segment 61 may include a segment omission section a1, a segment height variable section a2, and a segment height uniform section a3 in order from the core side to the outer peripheral side. However, since the plain portion of the second portion B3 is not bent, the radial length of the bent surface region F may be shorter than that in the above-described embodiment.

[0436] As shown in FIGS. 11a, 11b, and 11c, the bent surface region F includes a lamination number uniform section b1 adjacent to the segment omission section a1 and having a lamination number of 10 or more.

[0437] The bent surface region F may also include a lamination number decreasing section b2 adjacent to the winding turn of the second portion B3 of the electrode assembly 100 and having the lamination number decreasing toward the outer peripheral side. Preferably, the lamination number uniform section b1 can be set as a welding target region.

[0438] In the bent surface region F, the preferred numerical ranges of the ratio (a2 / c) of the segment height variable section a2, the ratio (b1 / c) of the lamination number uniform section b1, and the ratio of the area of the lamination number uniform section b1 to the area of the bent surface region F with respect to the radial length (c) where the segment exists have been described above, and repeated explanations are omitted.

[0439] The first current collector plate 144 may be welded to the bent surface region F of the first plain portion 146a, and the second current collector plate 145 may be welded to the bent surface region F of the second plain portion 146b.

[0440] The overlapping relationship between the lamination number uniform section b1 and the lamination number decreasing section b2 and the welding region W, the outer diameters of the first current collector plate 144 and the second current collector plate 145, the configuration in which the first portion B1 does not block the core, etc. are substantially the same as described above.

[0441] On the other hand, the second part B3 does not include a slit piece, and the height of the plain part is lower than that of the slit piece of the third part B2. Therefore, when the slit piece of the third part B2 is bent, the second part B3 is not substantially bent. Further, since the winding turns of the second part B3 are sufficiently separated from the beading part 147, it is possible to solve the problem that the winding turns of the second part B3 are damaged during the process of pushing in the beading part 147.

[0442] FIG. 20 is a cross-sectional view of a cylindrical battery 220 cut along the Y-axis direction according to still another embodiment of the present invention.

[0443] Referring to FIG. 20, the cylindrical battery 220 includes the electrode assembly 100 shown in FIG. 13, and other configurations except for the electrode assembly 100 are substantially the same as those of the cylindrical battery 200 shown in FIG. 18. Therefore, the configurations described with reference to FIGS. 13 and 18 can be substantially similarly applied also in the present embodiment.

[0444] Preferably, the first plain part 146a and the second plain part 146b of the electrode assembly 100 include a plurality of slit pieces 61. Further, the slit pieces 61 are bent from the outer peripheral side to the core side of the electrode assembly 100 to form a bent surface region F. At this time, the first part B1 and the second part B3 of the first plain part 146a have a lower height of the plain part than other parts and do not include slit pieces, so they are not substantially bent toward the core side. The same applies to the second plain part 146b.

[0445] Therefore, also in the present embodiment, similar to the embodiment of FIG. 19, the bent surface region F may include a slit piece omission section a1, a slit piece height variable section a2, and a slit piece height uniform section a3 in order from the core side to the outer peripheral side. However, since the plain part of the second part B3 is not bent, the radial length of the bent surface region F may be shorter than that of the above-described embodiment.

[0446] The bent surface region F includes a lamination number uniform section b1 adjacent to the slit piece omission section a1 and having a lamination number of 10 or more as shown in FIGS. 11a, 11b, and 11c.

[0447] The bent surface region F may also include a lamination number reduction section b2 where the number of laminated segments decreases toward the outer peripheral side adjacent to the winding turns of the second portion B3 of the electrode assembly 100. Preferably, the lamination number uniform section b1 can be set as a welding target region.

[0448] In the bent surface region F, the ratio (a2 / c) of the height variable section a2 of the segmented piece, the ratio (b1 / c) of the lamination number uniform section b1 of the segmented piece, and the preferable numerical range of the ratio of the area of the lamination number uniform section b1 to the area of the bent surface region F are as described above, so repeated explanations are omitted.

[0449] The first current collector plate 144 can be welded to the bent surface region F of the first plain portion 146a, and the second current collector plate 176 can be welded to the bent surface region F of the second plain portion 146b.

[0450] The overlapping relationship between the lamination number uniform section b1 and the lamination number reduction section b2 and the welding region W, the outer diameters of the first current collector plate 144 and the second current collector plate 176, the configuration where the first portion B1 does not block the core, etc. are substantially as described above.

[0451] In the above-described embodiments (modifications), the first current collector plate 144 and the second current collector plate 176 included in the cylindrical batteries 200 and 220 including the rivet terminals 172 may have an improved structure as shown in FIGS. 21 and 22.

[0452] The improved structures of the first current collector plate 144 and the second current collector plate 176 can contribute to reducing the resistance of the cylindrical battery, improving the vibration resistance, and improving the energy density. In particular, the first current collector plate 144 and the second current collector plate 176 are effective when applied to a large cylindrical battery having a ratio of height to diameter greater than 0.4.

[0453] FIG. 21 is a top view showing the structure of the first current collector plate 144 according to an embodiment of the present invention.

[0454] Referring to FIGS. 20 and 21, the first current collector 144 may include a peripheral portion 144a, a first non-textured portion coupling portion 144b, and a terminal coupling portion 144c. The peripheral portion 144a is disposed on the upper portion of the electrode assembly 100. The peripheral portion 144a has a substantially rim-shaped form with an empty space S formed therein. open It may have a substantially rim (rim) form with an empty space S formed therein. Although the drawings show only the case where the peripheral portion 144a has a substantially circular rim form, the present invention is not limited thereby. The peripheral portion 144a may have a substantially square rim form, a hexagonal rim form, an octagonal rim form, or other rim forms different from the illustration. The number of the peripheral portions 144a may be increased to two or more. In this case, still other peripheral portions in the form of a rim may be included inside the peripheral portion 144a.

[0455] The terminal coupling portion 144c may have a diameter that is the same as or larger than the diameter of the flat portion 172c formed on the bottom surface of the rivet terminal 172 in order to secure a welding area for coupling with the flat portion 172c formed on the bottom surface of the rivet terminal 172.

[0456] The first non-textured portion coupling portion 144b extends inward from the peripheral portion 144a and is coupled to the bent surface region F of the non-textured portion 146a by welding. The terminal coupling portion 144c is located inside the peripheral portion 144a at a distance from the first non-textured portion coupling portion 144b. The terminal coupling portion 144c may be coupled to the rivet terminal 172 by welding. The terminal coupling portion 144c may be located, for example, at a substantially central portion of the inner space S open surrounded by the peripheral portion 144a. The terminal coupling portion 144c may be provided at a position corresponding to a hole formed in the core C of the electrode assembly 100. The terminal coupling portion 144c may be configured to cover the hole formed in the core C of the electrode assembly 100 so that the hole formed in the core C of the electrode assembly 100 does not expose outside the terminal coupling portion 144c. Therefore, the terminal coupling portion 144c may have a diameter or width larger than the hole formed in the core C of the electrode assembly 100.

[0457] The first non-ground portion coupling part 144b and the terminal coupling part 144c are not directly connected but are spaced apart and can be indirectly connected by the peripheral part 144a. Thus, the first current collector plate 144 has a structure in which the first non-ground portion coupling part 144b and the terminal coupling part 144c are not directly connected but are connected through the peripheral part 144a. When impact and / or vibration occur in the cylindrical battery 220, the impact applied to the coupling site between the first non-ground portion coupling part 144b and the first non-ground portion 146a and the coupling site between the terminal coupling part 144c and the rivet terminal 172 can be dispersed. Although four first non-ground portion coupling parts 144b are shown in the drawing, the present invention is not limited thereby. The number of the first non-ground portion coupling parts 144b can be determined variously in consideration of the manufacturing difficulty due to the complexity of the shape, the electrical resistance, the inner space S of the peripheral part 144a considering the electrolyte impregnation property, etc. open can be determined variously in consideration of such factors.

[0458] The first current collector plate 144 may further include a bridge part 144d that extends inward from the peripheral part 144a and is connected to the terminal coupling part 144c. At least a part of the cross-sectional area of the bridge part 144d may be formed smaller than that of the first non-ground portion coupling part 144b and the peripheral part 144a. For example, at least a part of the bridge part 144d may be formed to have a smaller width and / or thickness than the first non-ground portion coupling part 144b. In this case, the electrical resistance increases in the bridge part 144d. As a result, when current flows through the bridge part 144d, a relatively large resistance causes melting by overcurrent heating in a part of the bridge part 144d, which irreversibly shuts off the overcurrent. The cross-sectional area of the bridge part 144d can be adjusted to an appropriate level in consideration of such an overcurrent cutoff function.

[0459] The bridge portion 144d may include a tapered portion 144e whose width gradually narrows from the inner surface of the peripheral portion 144a toward the terminal connection portion 144c. When the tapered portion 144e is provided, the rigidity of the component is improved at the connection site between the bridge portion 144d and the peripheral portion 144a. When the tapered portion 144e is provided, in the manufacturing process of the cylindrical battery 220, for example, by a transfer device and / or an operator gripping the tapered portion 144e, the first current collector 144 and / or the combined body of the first current collector 144 and the electrode assembly 100 can be transferred easily and safely. That is, when the tapered portion 144e is provided, defects of the product generated by gripping the portions welded to other components such as the first plain portion connection portion 144b and the terminal connection portion 144c can be prevented.

[0460] A plurality of the first plain portion connection portions 144b may be provided. The plurality of the first plain portion connection portions 144b may be arranged at the same interval along the extending direction of the peripheral portion 144a. The lengths by which the plurality of the first plain portion connection portions 144b extend may be substantially the same as each other. The first plain portion connection portion 144b may be joined to the bent surface region F of the plain portion 146a by laser welding. The welding may be replaced by ultrasonic welding, spot welding, or the like.

[0461] The welding pattern 144f formed by welding the first plain portion connection portion 144b and the bent surface region F may have a structure extending along the radial direction of the electrode assembly 100. The welding pattern 144f may be an array of a line pattern or a dot pattern.

[0462] The welding pattern 144f corresponds to the welding area. Therefore, it is preferable that the welding pattern 144f overlaps with the average lamination number section b1 of the bent surface area F by 50% or more. The welding pattern 144f that does not overlap with the average lamination number section b1 may overlap with the lamination number decreasing section b2. More preferably, the entire welding pattern 144f may overlap with the average lamination number section b1 of the bent surface area F. The average lamination number section b1, and optionally the lamination number decreasing section b2, of the bent surface area F below the point where the welding pattern 144f is formed preferably have a lamination number of 10 or more for the segmented slice.

[0463] The terminal connection part 144c may be arranged so as to be surrounded by a plurality of the first plain part connection parts 144b. The terminal connection part 144c may be joined to the flat part 172c of the rivet terminal 172 by welding. The bridge part 144d may be located between a pair of adjacent first plain part connection parts 144b. In this case, the distance from the bridge part 144d to one of the pair of first plain part connection parts 144b along the extension direction of the peripheral part 144a may be substantially the same as the distance from the bridge part 144d to the other of the pair of first plain part connection parts 144b along the extension direction of the peripheral part 144a. The cross-sectional area of each of the plurality of first plain part connection parts 144b may be formed to be substantially the same. The width and thickness of each of the plurality of first plain part connection parts 144b may be formed to be substantially the same.

[0464] Although not shown, a plurality of the bridge parts 144d may be provided. Each of the plurality of bridge parts 144d may be arranged between a pair of adjacent first plain part connection parts 144b. The plurality of bridge parts 144d may be arranged at substantially the same interval along the extension direction of the peripheral part 144a. The distance from each of the plurality of bridge parts 144d to one of the pair of adjacent first plain part connection parts 144b along the extension direction of the peripheral part 144a may be substantially the same as the distance to the other first plain part connection part 144b.

[0465] As described above, when a plurality of the first non-patterned portion coupling portions 144b and / or the bridge portions 144d are provided, if the distance between the first non-patterned portion coupling portions 144b and / or the distance between the bridge portions 144d and / or the distance between the first non-patterned portion coupling portion 144b and the bridge portion 144d are formed to be constant, the flow of current from the first non-patterned portion coupling portion 144b toward the bridge portion 144d or the flow of current from the bridge portion 144d toward the first non-patterned portion coupling portion 144b is smoothly formed.

[0466] The bridge portion 144d may include a notching portion N formed so as to partially reduce the cross-sectional area of the bridge portion 144d. Adjustment of the cross-sectional area of the notching portion N can be realized, for example, through a partial reduction in the width and / or thickness of the bridge portion 144d. When the notching portion N is provided, the electrical resistance in the region where the notching portion N is formed increases, thereby enabling rapid current interruption when an overcurrent occurs.

[0467] The notching portion N is preferably provided in a region corresponding to the stacked number uniform section of the electrode assembly 100 in order to prevent foreign matter generated at the time of breakage from flowing into the inside of the electrode assembly 100. In this region, the stacked number of the divided sections of the non-patterned portion 146a is maintained at a maximum, and thus the overlapping divided sections can function as a mask.

[0468] The notching portion N can be covered with an insulating tape. Then, since the heat generated at the notching portion N is not dissipated to the outside, when an overcurrent flows through the bridge portion 144d, the notching portion N breaks more rapidly.

[0469] FIG. 22 is a top view showing the structure of the second current collector plate 176 according to an embodiment of the present invention.

[0470] Referring to FIGS. 20 and 22, the second current collector 176 is disposed at the lower part of the electrode assembly 100. Further, the second current collector 176 may be configured to electrically connect the plain portion 146b of the electrode assembly 100 and the battery housing 171. The second current collector 176 is made of a conductive metal material and is electrically connected to the bent surface region F of the plain portion 146b. Further, the second current collector 176 is electrically connected to the battery housing 171. The second current collector 176 may be fixed with its peripheral portion interposed between the inner surface of the battery housing 171 and the first gasket 178b. Specifically, the peripheral portion of the second current collector 176 may be interposed between the lower surface of the beading portion 180 of the battery housing 171 and the first gasket 178b. However, the present invention is not limited thereto, and alternatively, the peripheral portion of the second current collector 176 may be welded to the inner wall surface of the battery housing 171 in a region where the beading portion 180 is not formed.

[0471] The second current collector 176 may include a support portion 176a disposed at the lower part of the electrode assembly 100, a second non-textured portion coupling portion 176b extending substantially along the radial direction of the electrode assembly 100 from the support portion 176a and coupled to the bent surface region F of the non-textured portion 146b, and a housing coupling portion 176c extending obliquely from the support portion 176a toward the inner surface of the battery housing 171 with reference to the radial direction of the electrode assembly 100 and coupled to the inner surface. The second non-textured portion coupling portion 176b and the housing coupling portion 176c are indirectly connected through the support portion 176a and are not directly connected to each other. Therefore, when an external impact is applied to the cylindrical battery 220 according to an embodiment of the present invention, damage generated at the coupling site between the second current collector 176 and the electrode assembly 100 and at the coupling site between the second current collector 176 and the battery housing 171 can be minimized. However, the second current collector 176 according to an embodiment of the present invention is not limited only to the case having a structure in which the second non-textured portion coupling portion 176b and the housing coupling portion 176c are indirectly connected in this way. For example, the second current collector 176 may have a structure that does not include the support portion 176a for indirectly connecting the second non-textured portion coupling portion 176b and the housing coupling portion 176c and / or a structure in which the non-textured portion 146b and the housing coupling portion 176c are directly connected.

[0472] The support portion 176a and the second non-textured portion coupling portion 176b are disposed at the lower part of the electrode assembly 100. The second non-textured portion coupling portion 176b is coupled to the bent surface region F of the non-textured portion 146b. Not only the second non-textured portion coupling portion 176b but also the support portion 176a may be coupled to the non-textured portion 146b. The second non-textured portion coupling portion 176b and the bent surface region F of the non-textured portion 146b may be coupled by laser welding. The welding can be replaced by ultrasonic welding, spot welding, etc. The support portion 176a and the second non-textured portion coupling portion 176b are located above the beading portion 180 when the beading portion 180 is formed on the battery housing 171.

[0473] The support portion 176a includes a current collector plate hole 176d formed at a position corresponding to a hole formed in the core C of the electrode assembly 100. The core C of the electrode assembly 100 and the current collector plate hole 176d that communicate with each other can function as a passage for inserting a welding rod for welding between the rivet terminal 172 and the terminal coupling portion 144c of the first current collector plate 144 or for irradiating a laser beam.

[0474] The current collector plate hole 176d has a radius of 0.5r c or more with respect to the radius r of the hole formed in the core C of the electrode assembly 100. When the radius of the current collector plate hole 176d is 0.5r c ~1.0r c When the radius of the current collector plate hole 176d is 0.5r c ~1.0r, when a vent occurs in the cylindrical battery 220, a phenomenon in which the separator or the winding structure of the electrode near the core C of the electrode assembly 100 is pushed out to the outside of the core C due to the vent pressure is prevented. When the radius of the current collector plate hole 176d is greater than 1.0r c the core C is maximally opened, so that the injection of the electrolyte in the electrolyte injection step becomes easy.

[0475] When a plurality of the second plain portion coupling portions 176b are provided, the plurality of second plain portion coupling portions 176b may have a form extending from the support portion 176a of the second current collector plate 176 substantially radially toward the side wall of the battery housing 171. Each of the plurality of second plain portion coupling portions 176b may be spaced apart from each other along the circumference of the support portion 176a.

[0476] A plurality of the housing coupling portions 176c may be provided. In this case, the plurality of housing coupling portions 176c may be configured to extend radially from the central portion of the second current collector 176 toward the side wall of the battery housing 171. As a result, the electrical connection between the second current collector 176 and the battery housing 171 may be made at a plurality of points. By making the coupling for electrical connection at such a plurality of points, the coupling area can be maximized and the electrical resistance can be minimized. Each of the plurality of housing coupling portions 176c may be spaced apart from each other along the periphery of the support portion 176a. At least one housing coupling portion 176c may be located between adjacent second plain portion coupling portions 176b. The plurality of housing coupling portions 176c may be coupled to, for example, the beading portion 180 on the inner surface of the battery housing 171. The housing coupling portion 176c may be coupled to the lower surface of the beading portion 180 by laser welding in particular. The welding can be replaced by ultrasonic welding, spot welding, or the like. By welding and coupling a plurality of housing coupling portions 176c on the beading portion 180 in this way, the current path can be radially dispersed to limit the resistance level of the cylindrical battery 220 to about 4 mΩ or less. Further, by forming the lower surface of the beading portion 180 to extend in a direction substantially parallel to the upper surface of the battery housing 171, that is, in a direction substantially perpendicular to the side wall of the battery housing 171, and forming the housing coupling portion 176c also in the same direction, that is, in a radially extending and circumferentially extending form, the housing coupling portion 176c can be stably brought into contact with the beading portion 180. Further, by stably bringing the housing coupling portion 176c into contact with the flat portion of the beading portion 180 in this way, welding between the two components is smoothly performed, whereby the coupling force between the two components is improved and an increase in resistance at the coupling site is minimized.

[0477] The housing coupling portion 176c may include a contact portion 176e coupled to the inner surface of the battery housing 171 and a connecting portion 176f connecting between the support portion 176a and the contact portion 176e.

[0478] The contact portion 176e is coupled to the inner surface of the battery housing 171. When the beading portion 180 is formed on the battery housing 171, the contact portion 176e can be coupled onto the beading portion 180 as described above. More specifically, the contact portion 176e can be electrically coupled to a flat portion formed on the lower surface of the beading portion 180 formed on the battery housing 171 and can be interposed between the lower surface of the beading portion 180 and the first gasket 178b. In this case, for stable contact and coupling, the contact portion 176e can have a form extending by a predetermined length along the circumferential direction of the battery housing 171 in the beading portion 180.

[0479] The connecting portion 176f can be bent at an obtuse angle. The bending point can be above the middle point of the connecting portion 176f. When the connecting portion 176f is bent, the contact portion 176e is stably supported on the flat surface of the beading portion 180. The connecting portion 176f is divided into a lower part and an upper part with the bending point as a reference, and the length of the lower part can be greater than that of the upper part. Also, the inclination angle based on the surface of the support portion 176a can be greater in the lower part of the bending point than in the upper part. When the connecting portion 176f is bent, it is possible to buffer the pressure (force) applied in the vertical direction of the battery housing 171. As an example, when pressure is transmitted to the contact portion 176e in the sizing process of the battery housing 171 and the contact portion 176e moves vertically toward the support portion 176a, the bending point of the connecting portion 176f moves upward while the connecting portion 176f is deformed, and through this, stress can be buffered.

[0480] On the other hand, the maximum distance from the central portion of the second current collector plate 176 along the radial direction of the electrode assembly 100 to the end of the second plain portion coupling portion 176b is preferably the same as or smaller than the inner diameter of the battery housing 171 in the region where the beading portion 180 is formed, that is, the minimum inner diameter of the battery housing 171. This is to prevent the phenomenon that the end of the second plain portion coupling portion 176b presses against the end of the electrode assembly 100 during the sizing process of compressing the battery housing 171 in the height direction.

[0481] The second non-coated portion joint 176b includes a hole 176g. The hole 176g can be used as a passage for the electrolyte to move. The welding pattern 176h formed by welding the second non-coated portion joint 176b and the bent surface region F may have a structure extending along the radial direction of the electrode assembly 100. The welding pattern 176h can be an array of line patterns or dot patterns.

[0482] The welding pattern 176h corresponds to a welding region. Therefore, it is preferable that the welding pattern 176h overlaps with the average number of laminations section b1 of the bent surface region F located at the lower part of the electrode assembly 100 by 50% or more. The welding pattern 176h that does not overlap with the average number of laminations section b1 may overlap with the decreasing number of laminations section b2. More preferably, the entire welding pattern 176h can overlap with the average number of laminations section b1 of the bent surface region F. The average number of laminations section b1 and, optionally, the decreasing number of laminations section b2 of the bent surface region F above the point where the welding pattern 176h is formed preferably have 10 or more laminations in the segment.

[0483] The above-described first current collector 144 and second current collector 176 have different outer diameters. The outer diameter is the outer diameter of the contact region between the bent surface region F and the current collector. The outer diameter is defined as the maximum value among the distances between two points where a straight line passing through the center of the core C of the electrode assembly intersects the end of the contact region. Since the second current collector 176 is located inside the beading portion, its outer diameter is smaller than the outer diameter of the first current collector 144. Also, the length of the welding pattern 144f of the first current collector 144 is even longer than the length of the welding pattern 176h of the second current collector 176. Preferably, the welding pattern 144f and the welding pattern 176h can extend from substantially the same point to the outer peripheral side with respect to the center of the core C.

[0484] The cylindrical batteries 200, 220 according to the embodiments of the present invention can be electrically connected at the upper part.

[0485] FIG. 23 is a top view showing a state in which a plurality of cylindrical batteries 200 are electrically connected, and FIG. 24 is a partially enlarged view of FIG. 23. The cylindrical battery 200 can be replaced with a cylindrical battery 220 having another structure.

[0486] Referring to FIGS. 23 and 24, a plurality of cylindrical batteries 200 can be connected in series and in parallel at the upper part of the cylindrical battery 200 using a bus bar 210. The number of the cylindrical batteries 200 can be increased or decreased in consideration of the capacity of the battery pack.

[0487] In each cylindrical battery 200, the rivet terminal 172 may have a positive polarity, and the flat surface 171a around the rivet terminal 172 of the battery housing 171 may have a negative polarity. Of course, the opposite is also possible.

[0488] Preferably, the plurality of cylindrical batteries 200 can be arranged in a plurality of rows and columns. In the drawing, the columns are in the vertical direction and the rows are in the horizontal direction. Also, in order to maximize the space efficiency, the cylindrical batteries 200 can be arranged in a closest packing structure. The closest packing structure is formed when an equilateral triangle is drawn when the centers of the rivet terminals 172 exposed outside the battery housing 171 are connected to each other. Preferably, the bus bar 210 connects the cylindrical batteries 200 arranged in the same column in parallel to each other, and connects the cylindrical batteries 200 arranged in two adjacent columns in series to each other.

[0489] Preferably, the bus bar 210 may include a body portion 211, a plurality of first bus bar terminals 212, and a plurality of second bus bar terminals 213 for series and parallel connection.

[0490] The body portion 211 may extend along the column of the cylindrical battery 200 between adjacent rivet terminals 172. Alternatively, the body portion 211 may extend along the column of the cylindrical battery 200, but may be regularly bent like a zigzag.

[0491] The plurality of first bus bar terminals 212 can extend from one side of the body portion 211 and be electrically coupled to the rivet terminal 172 of the cylindrical battery 200 located on one side. The electrical coupling between the first bus bar terminal 212 and the rivet terminal 172 can be performed by laser welding, ultrasonic welding, or the like.

[0492] The plurality of second bus bar terminals 213 can extend from the other side of the body portion 211 and be electrically coupled to the flat surface 171a around the rivet terminal 172 located on the other side. The electrical coupling between the second bus bar terminal 213 and the flat surface 171a can be performed by laser welding, ultrasonic welding, or the like.

[0493] Preferably, the body portion 211, the plurality of first bus bar terminals 212, and the plurality of second bus bar terminals 213 can be formed from a single conductive metal plate. The metal plate can be, for example, an aluminum plate or a copper plate, but the present invention is not limited thereto. As a modification, the body portion 211, the plurality of first bus bar terminals 212, and the second bus bar terminals 213 may be manufactured in separate piece units and then joined together by welding or the like.

[0494] The cylindrical battery 200 according to an embodiment of the present invention described above has a structure in which resistance is minimized through an increase in the welding area through the bent surface region F, multiplexing of the current path using the second current collector plate 176, minimization of the current path length, and the like. The AC resistance of the cylindrical battery 200 measured by a resistance measuring device between the positive electrode and the negative electrode, that is, between the rivet terminal 172 and the flat surface 171a around it, can be about 4 mΩ or less, which is suitable for rapid charging.

[0495] In the cylindrical battery 200 according to an embodiment of the present invention, since the rivet terminal 172 having a positive polarity and the flat surface 171a having a negative polarity are located in the same direction, electrical connection between the cylindrical batteries 200 can be easily realized using the bus bar 210.

[0496] In addition, since the rivet terminal 172 of the cylindrical battery 200 and the flat surface 171a around it have a large area, a sufficient bonding area of the bus bar 210 can be ensured, and the resistance of the battery pack including the cylindrical battery 200 can be sufficiently reduced.

[0497] Also, since electrical wiring can be performed at the upper part of the cylindrical battery 200, the energy density per unit volume of the battery module / pack can be maximized.

[0498] The cylindrical battery according to the above-described embodiment (modification) is used for manufacturing a battery pack.

[0499] FIG. 25 is a diagram schematically showing the configuration of a battery pack according to an embodiment of the present invention.

[0500] Referring to FIG. 25, a battery pack 300 according to an embodiment of the present invention includes an assembly in which cylindrical batteries 301 are electrically connected, and a pack housing 302 that houses the same. The cylindrical battery 301 can be any one of the batteries according to the above-described embodiment (modification). For convenience of illustration, components such as a bus bar, a cooling unit, and external terminals for electrical connection of the cylindrical battery 301 are not shown.

[0501] The battery pack 300 is mounted on an automobile. The automobile can be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The automobile includes a four-wheel vehicle or a two-wheel vehicle.

[0502] FIG. 26 is a diagram for explaining an automobile including the battery pack 300 of FIG. 25.

[0503] Referring to FIG. 26, 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 power supply from the battery pack 300 according to an embodiment of the present invention.

[0504] According to an embodiment of the present invention, by using the plain portions protruding above and below the electrode assembly itself as electrode tabs, the internal resistance of the battery can be reduced and the energy density can be increased.

[0505] Further, according to an embodiment of the present invention, by improving the structure of the plain portion of the electrode assembly, the electrode assembly and the inner peripheral surface of the battery housing do not interfere with each other during the process of forming the beading portion of the battery housing, and an internal short circuit of the cylindrical battery due to partial deformation of the electrode assembly can be prevented.

[0506] Further, according to an embodiment of the present invention, by improving the structure of the plain portion of the electrode assembly, it is possible to prevent the phenomenon that the plain portion is torn when the plain portion is bent, and to sufficiently increase the number of overlapping layers of the plain portion to improve the welding strength of the current collector.

[0507] Further, according to an embodiment of the present invention, a plurality of slitting sections are formed in the plain portion of the electrode. When the electrode is wound, the plurality of slitting sections are aligned and arranged in a predetermined direction, and the ends of the active material layer formed on the electrode in the region where the slitting sections are not arranged are exposed from between the winding turns of the separator, so that the electrolyte impregnation property (speed and uniformity) can be increased.

[0508] Further, according to an embodiment of the present invention, by applying a slitting section structure to the plain portion of the electrode and optimizing the dimensions (width, height, separation pitch) of the slitting sections, and sufficiently increasing the number of stacked slitting sections in the region used as the welding target region, the physical properties of the region where the current collector plate is welded can be improved.

[0509] Further, according to an embodiment of the present invention, when a plurality of slitting section structures are formed by repeatedly forming cutting grooves along the winding direction in the plain portion of the electrode, by optimizing the lower structure of the cutting grooves, it is possible to provide an electrode assembly with improved notching quality of the cutting grooves.

[0510] Further, according to one embodiment of the present invention, when forming a plurality of segmented pieces by repeatedly forming cutting grooves along the winding direction in the non-patterned portion of the electrode, by relatively adjusting the height of the non-patterned portion at the lower part of the cutting groove and the height of the non-patterned portion in the region adjacent to the core of the electrode assembly, it is possible to provide an electrode assembly capable of preventing the shape of the core from collapsing during the process of bending the segmented pieces.

[0511] Further, according to one embodiment of the present invention, by applying a structure in which a current collector plate is welded to a wide area on the bent surface region formed by bending the segmented pieces, it is possible to provide an electrode assembly with improved energy density and reduced resistance.

[0512] Further, according to one embodiment of the present invention, it is possible to provide a cylindrical battery with an improved design for electrical wiring at the upper part.

[0513] Further, according to one embodiment of the present invention, by improving the structure of the non-patterned portion adjacent to the core of the electrode assembly, it is possible to prevent the cavities in the core of the electrode assembly from being blocked when the non-patterned portion is bent, and to easily perform the electrolyte injection process and the welding process between the battery housing (or rivet terminal) and the current collector plate.

[0514] Further, according to one embodiment of the present invention, it is possible to provide a cylindrical battery having a structure with low internal resistance, prevention of internal short circuit, and improved welding strength between the current collector plate and the non-patterned portion, a battery pack including the same, and an automobile.

[0515] In particular, one aspect of the present invention can provide a cylindrical battery with a ratio of height to diameter of 0.4 or more and a resistance of 4 mΩ or less, a battery pack including the same, and an automobile.

[0516] As described above, the present invention has been described with reference to limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations are possible within the equivalent scope of the technical idea and claims of the present invention by those with ordinary knowledge in the technical field to which the present invention pertains.

Description of Symbols

[0517] 41 Current collector 42 Active material layer 43 Plain part 43a First plain part 43b Second plain part 44 Insulating coating layer 60 Electrode 61 Divided slice 63 Cutting groove 63a Side part 63b Round part 65 Electrode assembly 66 Independent region 70 Electrode 80 Electrode assembly 140 Battery 141 Electrode assembly 142 Battery housing 143 Sealing body 143a Cap plate 143b First gasket 143c Connecting plate 143d Protrusion 144 First current collecting plate 145 Second current collecting plate 146 Insulator 146a First plain part 146b Second plain part 147 Beading part 148 Crimping part 149 Lead 150 Width ratio 151 Lead hole 152 Bending part 171 Battery housing 172 Rivet terminal 173 Second gasket 174 Insulator 176 Second current collecting plate 178 Sealing body 178a Cap plate 178b First gasket 179 Vent part 180 Beading part 181 Crimping part 190 Cylindrical battery 200 Cylindrical battery 210 Cylindrical battery 210 Bus bar 211 Body part 212 First bus bar terminal 213 Second bus bar terminal 220 Cylindrical battery 300 Battery pack 301 Cylindrical battery 302 Pack housing

Claims

1. An electrode assembly in which a first electrode, a second electrode, and a separation membrane interposed between the first electrode and the second electrode are wound around a winding axis to define a core and an outer peripheral surface, wherein the first electrode includes a first active material portion coated with an active material layer along the winding direction, and a first plain portion not coated with the active material layer and exposed outside the separation membrane, the first plain portion includes a first portion adjacent to the core of the electrode assembly, a second portion adjacent to the outer peripheral surface of the electrode assembly, and a third portion between the first portion and the second portion, the third portion includes a plurality of segmented pieces spaced apart in the winding direction by a plurality of cutting grooves extending in the winding axis direction, the height of the first portion is relatively lower than the height of the plain portion at the lower end of the cutting groove, the electrode assembly.

2. Based on the end of the active material layer, the height of the first portion is 0% to 95% compared to the height of the plain portion at the lower end of the cutting groove, the electrode assembly according to claim 1.

3. The height of the first portion is 37.5% to 62.5% compared to the height of the plain portion at the lower end of the cutting groove, the electrode assembly according to claim 2.

4. further comprising an insulating coating layer covering the boundary between the first plain portion and the active material layer, Based on the end of the insulating coating layer, the height of the first portion is 0% to 95% compared to the height of the plain portion at the lower end of the cutting groove, the electrode assembly according to any one of claims 1 to 3.

5. The height of the first portion is 37.5% to 62.5% compared to the height of the plain portion at the lower end of the cutting groove, the electrode assembly according to claim 4.

6. The height of the second portion is relatively lower than the height of the plain portion at the lower end of the cutting groove, the electrode assembly according to any one of claims 1 to 3.

7. Based on the end of the active material layer, the height of the second portion is 0% to 95% compared to the height of the plain portion at the lower end of the cutting groove, the electrode assembly according to claim 6.

8. The height of the second portion is 37.5% to 62.5% compared to the height of the plain portion at the lower end of the cutting groove, the electrode assembly according to claim 7.

9. further comprising an insulating coating layer covering the boundary between the first plain portion and the active material layer, The electrode assembly according to claim 6, wherein, with reference to the end of the insulating coating layer, the height of the second portion is 0% to 95% compared to the height of the unpatterned portion at the lower end of the cutting groove.

10. The electrode assembly according to claim 9, wherein the height of the second portion is 37.5% to 62.5% compared to the height of the unpatterned portion at the lower end of the cutting groove.

11. The electrode assembly according to any one of claims 1 to 3, wherein the current collector of the first electrode is thinner than the current collector of the second electrode.

12. The electrode assembly according to claim 11, wherein the current collector of the first electrode is a copper foil and the current collector of the second electrode is an aluminum foil.

13. The electrode assembly according to any one of claims 1 to 3, wherein the first electrode is a negative electrode.

14. An electrode assembly according to any one of claims 1 to 3, a battery housing including an open end and a bottom opposing the open end, accommodating the electrode assembly in a space between the open end and the bottom, and having a first polarity electrically connected to one of the first electrode and the second electrode, a sealing body for sealing the open end of the battery housing, a battery including a terminal having a second polarity electrically connected to the other of the first electrode and the second electrode and having a surface exposed to the outside.

15. The sealing body includes a cap plate for sealing the open end portion of the battery housing and a gasket wrapped around the periphery of the cap plate and crimped to the open end portion of the battery housing. The battery according to claim 14, wherein the terminal having the second polarity is the cap plate.

16. Further including a current collector electrically connected to the unpatterned portion of the first electrode having the first polarity and having at least a part of its periphery coupled to the side wall of the battery housing. The sealing body includes a cap plate and a gasket wrapped around the periphery of the cap plate and crimped to the open end portion of the battery housing. The battery according to claim 14, wherein the battery housing is insulatingly attached to a through hole formed in the central portion of the bottom and includes a rivet terminal electrically connected to the second electrode and having the second polarity.

17. The battery according to claim 16, wherein the cap plate has no polarity.

18. A battery pack including a plurality of the batteries according to claim 14.

19. An automobile comprising the battery pack according to claim 18.

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