Cylindrical battery, battery pack, and motor vehicle

Abstract

The present invention discloses a cylindrical battery, a battery pack including the cylindrical battery, and an automobile. The cylindrical battery includes an electrode assembly in which a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are wound around a winding axis to define a core and an outer peripheral surface, and a cylindrical battery housing for housing the electrode assembly. When a first sector region surrounded by a first straight line passing through the core-side end portion of the first electrode from the center of the core, a second straight line passing through the core-side end portion of the second electrode from the center of the core, and the outer peripheral surface is defined as a stress vulnerable region, and a second sector region surrounded by a third straight line passing through the outer peripheral-side end portion of the first electrode from the center of the core, a fourth straight line passing through the outer peripheral-side end portion of the second electrode from the center of the core, and the outer peripheral surface is defined as a stress amplification region, the electrode assembly has a winding structure in which at least the outer peripheral-side end portion of the first electrode in the stress amplification region is separated from the inside of the stress vulnerable region along the circumferential direction.

Description

Technical Field

[0001] The present invention relates to a cylindrical battery, a battery pack, and a vehicle, and more particularly, to a cylindrical battery capable of maintaining the symmetry and circularity of the core of an electrode assembly even when the charge-discharge cycle increases by adjusting the positions of the ends of the positive electrode and the negative electrode in the winding direction, a battery pack including the same, and a vehicle.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0089226 filed on July 19, 2022, and all of the contents disclosed in the specification and drawings of the application are incorporated herein.

Background Art

[0003] Secondary batteries (batteries) with high applicability for each product group and electrical characteristics such as high energy density are generally applied not only to portable devices but also to electric vehicles (EVs) driven by motors, hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), etc.

[0004] Hereinafter, the term "electric vehicle" is used as a term referring to a vehicle including a motor driven by electricity such as an EV, an HEV, a PHEV, etc.

[0005] Secondary batteries have not only the primary advantage of significantly reducing the use of fossil fuels but also the advantage of generating no by-products due to energy use, and thus are attracting attention as an environmentally friendly new energy source for improving energy efficiency.

[0006] 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 a single secondary battery is about 2.5V to 4.5V. Therefore, when a higher output voltage is required, multiple batteries are connected in series to form a battery pack. Also, depending on the charge and discharge capacity required for the battery pack, multiple batteries may be connected in parallel to form a battery pack. Therefore, the number of batteries included in the battery pack and the electrical connection form can be variously set according to the required output voltage and / or charge and discharge capacity.

[0007] On the other hand, as types of secondary batteries, cylindrical, prismatic, 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 together with an electrolyte into the interior of a battery housing to constitute a battery. 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, in a cylindrical battery having a form factor such as 1865, 2170, etc., 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.

[0008] However, according to the conventional cylindrical battery, since current is concentrated on the strip-shaped electrode tab combined with 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.

[0009] In small cylindrical batteries having a form factor such as 1865, 2170, etc., resistance and heat generation are not much of a problem. However, when increasing the form factor for applying a cylindrical battery to an electric vehicle, a problem may occur that the cylindrical battery catches fire while generating a large amount of heat around the electrode tab during the rapid charging process.

[0010] To solve such problems, a cylindrical battery (so-called tab-less cylindrical battery) is presented, which is designed such that a positive electrode non-coated portion and a negative electrode non-coated portion are located at the upper and lower ends of a jelly roll type electrode assembly, respectively, and a current collector is welded to such non-coated portions to have a structure with improved current collection efficiency.

[0011] Figs. 1a to 1c are diagrams showing the manufacturing process of a tab-less cylindrical battery. Fig. 1a shows the structure of the electrode, Fig. 1b shows the electrode winding process, and Fig. 1c shows the process in which a current collector is welded to the folded surface of the non-coated portion. Fig. 1d is a cross-sectional view of the tab-less cylindrical battery cut in the longitudinal direction (Y-axis).

[0012] Referring to Figs. 1a to 1d, 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 non-coated portion 22 on one long side along the winding direction (X-axis).

[0013] The electrode assembly A is manufactured by laminating the positive electrode 10 and the negative electrode 11 in order together with two separator films 12 as shown in Fig. 1b, and then winding them in one direction (X-axis direction). At this time, the non-coated portion of the positive electrode 10 and the non-coated portion of the negative electrode 11 are arranged in opposite directions.

[0014] After the winding process, the non-coated portion 10a of the positive electrode 10 and the non-coated 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 non-coated portions 10a and 11a, respectively.

[0015] No separate electrode tabs are joined to the positive electrode non-coated portion 10a and the negative electrode non-coated portion 11a, and the current collectors 30 and 31 are connected to external electrode terminals. Since the current path is formed with a large cross-sectional area along the winding axis direction (see arrow) of the electrode assembly A, 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.

[0016] The electrode assembly A is inserted into the battery housing 32. The current collector 31 is welded to the bottom surface of the battery housing 32. On the upper side of the periphery of the current collector 30, a beading portion 33 is formed while the outer peripheral surface of the battery housing 32 is being pushed in. The inner surface of the beading portion 33 presses against the periphery of the current collector 30. Thereby, the electrode assembly A is firmly fixed inside the battery housing 32.

[0017] After the electrode assembly A is fixed within the battery housing 32, an electrolyte is injected into the interior of the battery housing 32. Thereafter, a cap assembly 34 is coupled to the open portion of the battery housing 32.

[0018] The cap assembly 34 may include a cap 34a, a connection plate 34c coupled to the lower portion of the cap 34a, and a sealing gasket 34b that seals the periphery of the cap 34a and the open portion of the battery housing 32.

[0019] A crimping portion 35 is provided above the beading portion 33. The crimping portion 35 is formed by bending the open portion of the battery housing 32 inward, and seals the open portion of the battery housing 32 by pressing the sealing gasket 34b against the surface of the periphery of the cap 34a.

[0020] The current collector 30 and the connection plate 34c may be electrically connected by a lead 30a. The lead 30a may be manufactured as a separate component and coupled to the current collector 30, or may be manufactured integrally with the current collector 30 and extend to and be coupled to the connection plate 34c.

[0021] An insulator 36 is disposed on the upper portion of the current collector 30. The periphery of the insulator 36 may be interposed between the beading portion 33 and the current collector 30. Thereby, the beading portion 33 presses the electrode assembly A toward the bottom of the battery housing 32 via the insulator 36.

[0022] On the one hand, as the number of charge-discharge cycles of the cylindrical battery 37 increases, a swelling phenomenon occurs and the internal pressure increases. The swelling phenomenon refers to the phenomenon in which the volume of the active material coated on the positive electrode 10 and the negative electrode 11 increases while charge and discharge are repeated. The degree of swelling is relatively large on the negative electrode 11 side. In the core of the electrode assembly A manufactured through the winding process, there is a cavity as a trace where the winding core member was inserted. Therefore, if the internal pressure of the cylindrical battery 37 increases due to the swelling phenomenon, stress is concentrated in the core direction of the electrode assembly A. This is because the battery housing is made of a highly rigid metal, and most of the stress is concentrated in the core direction of the electrode assembly A where there is an empty space.

[0023] If stress is generated in the electrode assembly A due to the swelling phenomenon, stress also acts in the circumferential direction. As a result, the positive electrode 10 and the negative electrode 11 rotate slightly while sliding with the separator interposed therebetween. Also, as the number of charge-discharge cycles increases, the amount of rotation of the positive electrode 10 and the negative electrode 11 accumulates, and the curvature changes locally while a fine gap is generated between the positive electrode 10 and the negative electrode 11 near the core. Therefore, even if the electrode assembly A immediately after winding has good symmetry and roundness, if the swelling phenomenon occurs, the symmetry and roundness of the electrode assembly A will change, different from the initial state.

[0024] Moreover, when the swelling phenomenon deepens in a state where the symmetry and roundness of the electrode assembly A have changed, a partial region of the core of the electrode assembly A collapses due to being unable to withstand the stress. In the process, the separator near the collapsed region is torn or fine cracks occur in the electrodes, which causes an internal short circuit, attracting attention as the main cause of a fire accident occurring inside the cylindrical battery.

[0025] Figs. 2a to 2c are cross-sectional views of the electrode assembly A schematically showing the process of collapse of the core of the electrode assembly A. These cross-sectional views show the surface obtained by cutting the electrode assembly A perpendicular to the axial direction.

[0026] Figure 2a shows the core structure of the electrode assembly A when the cylindrical battery 37 is in the BOL (Beginning of Life) state. Since steps are formed at the ends of the negative electrode and the positive electrode, the roundness decreases near the ends. Also, when straight lines L1 and L2 passing through the ends of the positive electrode and the negative electrode respectively are drawn from the center of the core, the winding turns of the electrodes located between L1 and L2 along the circumferential direction do not have a constant curvature and are changing.

[0027] Figure 2b shows a state where the charge-discharge cycle for the cylindrical battery 37 has proceeded several times, and the negative electrode and the positive electrode have rotated near the core while the volume of the electrodes, particularly the negative electrode, has increased. The change in the volume of the negative electrode is the largest when it is first charged during the activation process for the cylindrical battery 37. This is because the chemical substances causing the electrochemical reaction move from the positive electrode to the negative electrode and are inserted into the negative electrode.

[0028] The core of the electrode assembly A has a hollow part. Therefore, the rotation of the electrodes mainly occurs in the core. Of course, the electrodes also rotate slightly on the outer periphery of the electrode assembly A, but the degree is not at a significant level compared to the core side. This is because there is a hollow part in the core of the electrode assembly A, so the rotational freedom of the electrodes when rotational stress occurs is greater than that on the outer periphery of the electrode assembly A.

[0029] The increase in the volume of the negative electrode is relatively larger than that of the positive electrode. Also, in the vicinity of the core of the electrode assembly A, since the positive electrode is sandwiched between the winding turns of the negative electrode, a relatively larger frictional force acts on the surface of the positive electrode than on the surface of the negative electrode. Therefore, the amount of rotation of the negative electrode is larger than that of the positive electrode. This is because the larger the volume increase, the more rotational stress is generated, and the smaller the frictional force, the more it slides. In Figure 2b, it can be seen that the rotation of the positive electrode and the negative electrode is due to the fact that the core-side ends of the positive electrode and the negative electrode rotate clockwise. The direction in which the electrode ends rotate in the core of the electrode assembly is opposite to the winding direction.

[0030] Figure 2c shows the core structure when the charge-discharge cycle of the cylindrical battery 37 is performed hundreds of times and the swelling phenomenon deepens. Due to the deepening of the swelling condition, the end of the negative electrode has rotated to the point where the end of the positive electrode is located. As a result, a collapse phenomenon occurs in the core part. If the core collapses, the structure of the winding turn, which was in the shape of an arc swelling outward like the winding turns of the electrodes located from the 3 o'clock direction to the 6 o'clock direction, deforms into a shape swelling toward the core.

[0031] If the core of the electrode assembly A collapses as shown in Figure 2c, the close contact state between the positive electrode 10 and the negative electrode 11 cannot be maintained, and fine gaps are generated at the interface between the electrodes while the capacity of the battery suddenly decreases. Also, near the collapse region, the electrode and the separator sink toward the core side, and the separator is torn or fine cracks are generated in the electrode, whereby the positive electrode 10 and the negative electrode 11 come into contact with each other and an internal short circuit occurs.

[0032] The phenomenon of the core of the electrode assembly A collapsing becomes more serious as the diameter of the electrode assembly A increases. This is because as the diameter of the electrode assembly A increases, the rotational force in the circumferential direction generated by the increase in the volume of the electrodes further increases. Therefore, when manufacturing a large-diameter cylindrical battery such as the form factor 4680 (diameter: 46 mm, height: 80 mm), a special design capable of preventing the phenomenon of the core of the electrode assembly from collapsing is required.

Summary of the Invention

Problems to be Solved by the Invention

[0033] The present invention was devised to solve the above-described problems. The rotation of the positive and negative electrodes due to the swelling phenomenon of the cylindrical battery affects the symmetry and roundness of the electrode assembly. Therefore, in order to prevent the core of the electrode assembly from collapsing, it is necessary to optimally design the relative positions of the positive and negative electrodes in the electrode assembly in consideration of the rotation of the positive and negative electrodes.

[0034] When manufacturing a cylindrical battery, by adjusting the relative positions of the ends of the positive electrode and the ends of the negative electrode on the core side and the outer peripheral side of the electrode assembly, even if a swelling phenomenon occurs, during the use of the cylindrical battery, the symmetry and roundness of the core of the electrode assembly can be maintained, and one object of the present invention is to derive a design structure capable of preventing the collapse of the core.

[0035] Another object of the present invention is to provide a cylindrical battery including an electrode assembly optimally designed to improve the core collapse phenomenon, a battery pack including the cylindrical battery, and an automobile.

[0036] The technical problems of the present invention are not limited to the above-mentioned problems, and other objects and advantages can be understood from the following description and will be more clearly understood from the embodiments of the present invention. Also, the objects and advantages of the present invention can be realized by the means and combinations thereof shown in the claims.

Means for Solving the Problems

[0037] To achieve the above problems, a cylindrical battery according to one aspect of the present invention includes a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode, and an electrode assembly in which the core and the outer peripheral surface are defined by being wound around a winding axis, and a cylindrical battery housing for housing the electrode assembly.

[0038] On the cross-section of the electrode assembly perpendicular to the winding axis direction, a first fan-shaped region surrounded by a first straight line passing through the core-side end of the first electrode from the center of the core, a second straight line passing through the core-side end of the second electrode from the center of the core, and the outer peripheral surface is defined as a stress-vulnerable region, and a third straight line passing through the outer peripheral-side end of the first electrode from the center of the core, a fourth straight line passing through the outer peripheral-side end of the second electrode from the center of the core, and the outer peripheral surface can define a second fan-shaped region as a stress-amplifying region.

[0039] The electrode assembly may have a winding structure in which at least the outer peripheral side end portion of the first electrode among the stress amplification regions is separated from the inside of the stress vulnerable region along the circumferential direction.

[0040] The electrode assembly may have a winding structure in which the stress amplification region is separated from the stress vulnerable region along the circumferential direction on the cross section.

[0041] The outer peripheral region of the electrode assembly where the outer peripheral side end portion of the first electrode is located may be in close contact with the inner surface of the battery housing.

[0042] The position of the outer peripheral side end portion of the first electrode may be substantially fixed while the cylindrical battery is repeatedly charged and discharged.

[0043] On the cross section of the electrode assembly, with respect to a diameter line segment passing through the center of the core and perpendicular to a straight line that equally divides the central angle of the stress vulnerable region at equal angles, the cross section may be divided into a first semi-circular region and a second semi-circular region.

[0044] The electrode assembly may have a winding structure in which the stress vulnerable region is located in the first semi-circular region and the stress amplification region is located in the second semi-circular region.

[0045] The electrode assembly may have a winding structure in which at least a part of the stress amplification region overlaps with a third sector region in the second semi-circular region that is point-symmetrical to the stress vulnerable region with respect to the center of the core.

[0046] The electrode assembly may have a winding structure in which at least a part of the stress amplification region overlaps with a fifth straight line that equally divides the central angle of the third sector region at equal angles.

[0047] When a straight line that equally divides the third sector region that is point-symmetrical to the stress vulnerable region with respect to the center of the core is defined as the fifth straight line, the electrode assembly may have a winding structure in which the third straight line and the fourth straight line are located between the second straight line and the fifth straight line with respect to the circumferential direction on the cross section.

[0048] When the fifth straight line is a straight line that equally divides a third sector region that is point-symmetrical to the stress vulnerable region with respect to the center of the core, the electrode assembly may have a winding structure in which the third straight line and the fourth straight line are positioned between the first straight line and the fifth straight line with reference to the circumferential direction on the cross section.

[0049] When the fifth straight line is a straight line that equally divides a third sector region that is point-symmetrical to the stress vulnerable region with respect to the center of the core, the electrode assembly may have a winding structure in which the fourth straight line is positioned between the fifth straight line and the first straight line, and the third straight line is positioned between the fourth straight line and the second straight line with reference to the circumferential direction on the cross section.

[0050] When the fifth straight line is a straight line that equally divides a third sector region that is point-symmetrical to the stress vulnerable region with respect to the center of the core, the electrode assembly may have a winding structure in which the fourth straight line is positioned between the fifth straight line and the first straight line, and the third straight line is positioned between the fifth straight line and the second straight line with reference to the circumferential direction on the cross section.

[0051] When the fifth straight line is a straight line that equally divides a third sector region that is point-symmetrical to the stress vulnerable region with respect to the center of the core, the electrode assembly may have a winding structure in which the fourth straight line is positioned between the fifth straight line and the second straight line, and the third straight line is positioned between the fourth straight line and the first straight line with reference to the circumferential direction on the cross section.

[0052] When the fifth straight line is a straight line that equally divides a third sector region that is point-symmetrical to the stress vulnerable region with respect to the center of the core, the electrode assembly may have a winding structure in which the fourth straight line is positioned between the fifth straight line and the second straight line, and the third straight line is positioned between the fifth straight line and the first straight line with reference to the circumferential direction on the cross section.

[0053] The electrode assembly may have a winding structure in which, based on the circumferential direction on the cross section, the central angle between the first straight line and the fourth straight line is larger than the central angle between the second straight line and the third straight line.

[0054] The electrode assembly may have a winding structure in which, based on the circumferential direction on the cross section, the central angle between the second straight line and the fourth straight line is larger than the central angle between the first straight line and the third straight line.

[0055] The electrode assembly may have a winding structure in which, based on the center of the core, the central angle of the stress amplification region is smaller than the central angle of the stress vulnerable region.

[0056] The winding structure of the electrode assembly can be maintained while the cylindrical battery is charged and discharged 200 cycles or more, 300 cycles or more, 400 cycles or more, 500 cycles or more, 600 cycles or more, 700 cycles or more, 800 cycles or more, or 900 cycles or more.

[0057] One cycle may include full charge and full discharge. Full charge means charging in which the state of charge of the cylindrical battery increases from 0% to 100%. Full discharge means discharging in which the state of charge of the cylindrical battery decreases from 100% to 0%. The magnitude of the charging current and the charging temperature during full charge can be selected from the effective operating conditions of the cylindrical battery. Similarly, the magnitude of the discharging current and the discharging temperature during full discharge can be selected from the effective operating conditions of the cylindrical battery.

[0058] The first electrode and the second electrode may be a positive electrode and a negative electrode, respectively. At least a part of the winding turns of the negative electrode consisting only of the second electrode may be provided adjacent to the core side. The winding turns of the negative electrode that are at least partially opposed in the radial direction may be winding turns of the negative electrode.

[0059] A plurality of winding turns consisting only of the separator may be provided inside the winding turns of the negative electrode.

[0060] The first electrode and the second electrode may be a positive electrode and a negative electrode, respectively. The core-side end of the second electrode may further extend in a direction opposite to the winding direction of the electrode assembly than the core-side end of the first electrode to form at least a part of the innermost winding turn. The outer peripheral side end of the second electrode may further extend in the winding direction than the outer peripheral side end of the first electrode to form at least a part of the outermost winding turn.

[0061] The electrode assembly may have a winding structure in which the central angle of the stress vulnerable region is an angle of 30° or more and less than 180°, and the central angle of the stress amplification region is an angle of 10° or more and 90° or less.

[0062] The electrode assembly may have a winding structure in which the central angle of the stress vulnerable region is an angle of 87° or more, and the central angle of the stress amplification region is an angle of 32° or less.

[0063] The battery housing includes an open end and a bottom facing the open end, houses the electrode assembly in the space between the open end and the bottom, and may be electrically connected to one of the first electrode and the second electrode to have a first polarity.

[0064] The cylindrical battery may further include a sealing body that seals the open end of the battery housing, and a terminal that is electrically connected to the other of the first electrode and the second electrode and has a second polarity with its surface exposed to the outside.

[0065] The first electrode may include a first plain portion at a long side end along the winding direction of the electrode assembly.

[0066] The second electrode may include a second plain portion at a long side end along the winding direction.

[0067] The first non-coated portion may extend and protrude outside the separation membrane through one end portion of the electrode assembly, and may be bent toward the core side to form a first bent surface region. The first non-coated portion may include a plurality of divided sections separated by cutting grooves. The plurality of divided sections may be arranged along the winding direction of the electrode assembly. The first bent surface region may be formed by bending the plurality of divided sections in the radial direction of the electrode assembly.

[0068] The second non-coated portion may extend and protrude outside the separation membrane through the other end portion of the electrode assembly, and may be bent toward the core side to form a second bent surface region. The second non-coated portion may include a plurality of divided sections separated by cutting grooves. The plurality of divided sections may be arranged along the winding direction of the electrode assembly. The second bent surface region may be formed by bending the plurality of divided sections in the radial direction of the electrode assembly.

[0069] The cylindrical battery may further include a first current collector welded to the first bent surface region and / or a second current collector welded to the second bent surface region.

[0070] The welding region of the first current collector and / or the second current collector may have a radial structure with reference to the center of the core of the electrode assembly.

[0071] The welding structure between the first bent surface region and the first current collector and / or between the second bent surface region and the second current collector synergistically acts with the winding structure of the above-described electrode assembly to suppress the rotation of the electrodes during charging and discharging of the cylindrical battery.

[0072] The ratio of the height to the diameter of the cylindrical battery may be greater than 0.4.

[0073] The form factor of the cylindrical battery may be 46110, 4875, 48110, 4880, 4680 or 4695.

[0074] Further, the present invention is achieved by a battery pack including a plurality of the above-described cylindrical batteries, and an automobile including the battery pack.

Advantages of the Invention

[0075] According to one aspect of the present invention, in the electrode assembly of the cylindrical battery, by adjusting the relative positions of the ends of the positive electrode and the ends of the negative electrode on the core side and the outer peripheral side, even when a swelling phenomenon occurs, the symmetry and roundness of the electrode assembly can be maintained, and the collapse of the core can be prevented.

[0076] Also, according to one aspect of the present invention, a cylindrical battery including an electrode assembly having a structure capable of improving the core collapse phenomenon can be provided.

[0077] Also, according to one aspect of the present invention, a battery pack manufactured using a cylindrical battery having an improved structure, and an automobile including the battery pack can be provided.

[0078] The specific effects of the present invention, together with the above-described effects, will be described later together with the specific matters for implementing the invention.

[0079] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and are for the purpose of further understanding the technical idea of the present invention together with the detailed description of the invention. Therefore, the present invention is not to be construed as being limited only to the matters described in the drawings.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0081] The object, features, and advantages of the present invention will be described in detail below with reference to the accompanying drawings, whereby those having ordinary knowledge in the technical field to which the present invention pertains will be able to easily implement the technical idea of the present invention. In the description of the present invention, when it is determined that a specific description of related known technologies may obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals mean the same or similar components.

[0082] The terms such as first and second are used to indicate various components, but these components are not limited by such terms. These terms are merely used to distinguish one component from another, and unless otherwise specified, the first component may also be the second component.

[0083] Throughout the specification, unless otherwise specified, each component may be singular or plural.

[0084] Hereinafter, when any configuration is disposed “above (or below)” a component or “on (or under)” a component, it means that not only is any configuration disposed in contact with the upper surface (or lower surface) of the component, but other configurations may be interposed between the component and any configuration disposed above (or below) the component.

[0085] Also, when a certain component is said to be “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 another component.

[0086] In addition, as used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "composed of" or "including" are not necessarily construed to include all of the many components or many steps described in the specification, and some of the components or some of the steps may not be included, and additional components or steps may be further included.

[0087] Throughout the specification, "A and / or B" means A, B, or A and B unless otherwise specified, and "C to D" means C or more and D or less unless otherwise specified.

[0088] For convenience of explanation, in this specification, 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 direction). Further, the direction approaching or moving away from the winding axis is referred to as the radial direction or the radial direction (Z-axis direction). Among these, the direction particularly 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.

[0089] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0090] FIG. 3 is a cross-sectional view obtained by cutting a cylindrical battery according to an embodiment of the present invention perpendicular to the axial direction (Y-axis).

[0091] Referring to FIG. 3, the electrode assembly JR according to an embodiment of the present invention has a jelly roll structure in which a negative electrode A and a positive electrode B are wound around a single axis with a separator S interposed therebetween. In the embodiment, the positive electrode B may be the first electrode and the negative electrode A may be the second electrode, but the opposite case is also possible. The winding direction (X-axis) is counterclockwise, but it can be replaced with the clockwise direction. When the winding direction (X-axis) is clockwise, it is obvious that the rotation direction of the electrodes described later may be opposite to the description.

[0092] A hollow portion is formed in the core C of the electrode assembly JR. The hollow portion is an empty space. Alternatively, a center pin used in the winding process of the electrode assembly JR may be disposed in the hollow portion. There are two separation membranes S, which are respectively indicated by a dotted line and a dashed-dotted line. The arrangement structure of the separation membranes S can be variously deformed as long as it can insulate between the negative electrode A and the positive electrode B.

[0093] In the electrode assembly JR, the winding structures of the negative electrode A, the positive electrode B, and the separation membrane S are schematically shown. In the actual winding structure of the electrode assembly JR, the negative electrode A, the positive electrode B, and the separation membrane S are in close contact with each other.

[0094] The structure of the negative electrode A and / or the positive electrode B may have a structure in which no separate electrode tab is attached, as shown in FIGS. 14a to 14d and FIG. 15a. The present invention is effective in preventing or alleviating the core collapse of the electrode assembly JR having a structure in which the negative electrode A and / or the positive electrode B does not include a separate electrode tab. However, the present invention is also applicable without limitation to embodiments in which the negative electrode A and / or the positive electrode B includes a separate electrode tab.

[0095] Disclosed is a structure in which the electrode design (for example, the position of the electrode end, the core diameter, etc.) of the electrode assembly in which no separate electrode tab is coupled to the electrode non-coated portion is optimized to prevent the collapse of the core. In the electrode assembly JR, the negative electrode A is longer than the positive electrode B in the length in the winding direction (X axis).

[0096] The winding turns of the negative electrode A start earlier than those of the positive electrode B. The winding turns of the positive electrode B start after the winding turns of the negative electrode A have increased by a predetermined number of turns. The predetermined number of turns can be less than 1 turn or 1 or more turns. As an example, the winding turns of the negative electrode A that do not face the positive electrode B can be 0.5 turn to 5 turns. The winding turns near the core C around which only the negative electrode A is wound reinforce the structural rigidity of the core. However, the winding turns consisting only of the negative electrode A cannot contribute to the capacity of the cylindrical battery. Therefore, the number of winding turns of only the negative electrode A is appropriately selected in consideration of aspects of reinforcing the structural rigidity and aspects of the capacity. The winding turns near the core C around which only the negative electrode A is wound can face the winding turns of the adjacent negative electrodes in the radial direction. Although not shown, inside the winding turns consisting only of the negative electrode A, a plurality of winding turns consisting only of the separator S as shown in Fig. 2b can be provided. The winding turns consisting only of the separator S can also reinforce the structural rigidity of the core.

[0097] The present invention discloses a structure in which the positions of the ends of the negative electrode A and the positive electrode B are optimized to prevent the core from collapsing due to the rotational stress starting from the swelling phenomenon.

[0098] The ends of the negative electrode A and the positive electrode B mean the core-side end and the outer-periphery-side end in the winding turn structure of the negative electrode A and the positive electrode B. Preferably, the core-side end and the outer-periphery-side end can be the ends of the active material layer in the winding direction of the electrode assembly JR. Alternatively, the core-side end and the outer-periphery-side end can be the ends of the current collector coated with the active material layer. In another alternative, the core-side end and the outer-periphery-side end can be the ends of the current collector not coated with the active material layer.

[0099] For the sake of convenience of explanation, the present invention applies a two-dimensional polar coordinate system to a cross-section perpendicular to the axial direction of the electrode assembly JR to explain the optimization embodiments for the positions of the ends of the negative electrode A and the positive electrode B.

[0100] If a two-dimensional polar coordinate system is applied to the cross-sectional structure of the electrode assembly JR, the position within the cross-sectional structure can be represented by the distance (r) measured from the center of the polar coordinate system to the corresponding position and the angle measured in the circumferential direction (counterclockwise direction) to the corresponding position with respect to one coordinate (z-axis).

[0101] Even if the angular measurement direction of the said position is changed to the clockwise direction, the technical idea of the present invention can be applied substantially in the same manner.

[0102] Referring to FIG. 3, the core-side end A inner of the negative electrode A and the outer-periphery-side end A outer of the negative electrode A can be represented by θ A,inner and θ A,outer respectively.

[0103] Similarly, the core-side end B inner of the positive electrode B and the outer-periphery-side end B outer of the positive electrode B can be represented by θ B,inner and θ B,outer respectively.

[0104] The core-side end A inner of the negative electrode A may extend further in the direction opposite to the winding direction than the core-side end B inner of the positive electrode B to form at least a part of the innermost winding turn. Also, the outer-periphery-side end A outer of the negative electrode A may extend further in the winding direction than the outer-periphery-side end B outer of the positive electrode B to form at least a part of the outermost winding turn.

[0105] According to one embodiment, when the negative electrode A and the positive electrode B are wound in the counterclockwise direction, as the charge-discharge cycle is repeated, the core-side end A inner of the negative electrode A and the core-side end B inner of the positive electrode B rotate in the clockwise direction.

[0106] The amount of rotation is relatively larger when the initial cycle is performed than when the subsequent usage cycles are performed.

[0107] The initial cycle means the first charge after manufacturing a cylindrical battery including the electrode assembly JR, and performing an activation process to increase the state of charge of the cylindrical battery to a preset level. The usage cycles performed after the activation process include a full discharge that decreases the state of charge of the cylindrical battery to 0% and a full charge that increases the state of charge of the cylindrical battery to 100%.

[0108] When the usage cycles are repeated, the rotation amounts of the negative electrode A and the positive electrode B can increase linearly according to the increase in the usage cycles. When the number of usage cycles increases above a reference value, the rotation amount can converge close to 0 while gradually decreasing.

[0109] The swelling amount is relatively larger for the negative electrode A than for the positive electrode B. Also, since the innermost side of the electrode assembly JR includes winding turns consisting only of the negative electrode A, the degree of rotational freedom is higher than that of the positive electrode B. Also, the core-side end B of the positive electrode B inner is sandwiched between the winding turns of the negative electrode A, so the frictional force in the corresponding region is large. Therefore, the core-side end A of the negative electrode A inner has a larger rotation amount than the core-side end B of the positive electrode B inner .

[0110] As an example, the rotation amount of the core-side end A of the negative electrode A inner is several tens of degrees, and the rotation amount of the core-side end B of the positive electrode B inner can be less than ten degrees.

[0111] The outer peripheral side end A of the negative electrode A outer and the outer peripheral side end B of the positive electrode B outer rotate a little in the counterclockwise direction when the initial cycle is performed. If the initial cycle is performed, the outer peripheral portion of the electrode assembly JR corresponding to the outer peripheral side end B of the positive electrode B outer adheres closely to the inner surface of the can. Therefore, when the usage cycles after the initial cycle are repeated, the outer peripheral side end A of the negative electrode A outer and the outer peripheral side end B of the positive electrode B outer do not rotate at a significant level due to the anchor effect. Therefore, the outer peripheral side end A of the negative electrode A outer and the outer peripheral side end B of the positive electrode Bouter The angle with respect to [something] also does not change to a significant level during the progress of the usage cycles after the initial cycle due to the anchor effect.

[0112] According to other forms, on the cross-section of the electrode assembly JR, the first straight line L passing through the core-side end B of the positive electrode B from the center of the core C inner and the second straight line L passing through the core-side end A of the negative electrode A from the center of the core C B,inner The wound turn portion included in the first fan-shaped region surrounded by the outer periphery of the electrode assembly JR is vulnerable to the stress applied to the core C side during the swelling of the electrode assembly JR because the roundness decreases in the vicinity of the core C. inner and the outer periphery of the electrode assembly JR, the wound turn portion included in the first fan-shaped region surrounded by them is vulnerable to the stress applied to the core C side during the swelling of the electrode assembly JR. A,inner The wound turn portion included in the first fan-shaped region surrounded by the first straight line L passing through the core-side end B of the positive electrode B from the center of the core C, the second straight line L passing through the core-side end A of the negative electrode A from the center of the core C, and the outer periphery of the electrode assembly JR has a reduced roundness near the core C, so it is vulnerable to the stress applied to the core C side during the swelling of the electrode assembly JR.

[0113] According to still other forms, on the cross-section of the electrode assembly JR, the third straight line L passing through the outer-periphery-side end B of the positive electrode B from the center of the core C outer and the fourth straight line L passing through the outer-periphery-side end A of the negative electrode A from the center of the core B,outer The wound turn portion included in the second fan-shaped region surrounded by the third straight line L passing through the outer-periphery-side end B of the positive electrode B from the center of the core C, the fourth straight line L passing through the outer-periphery-side end A of the negative electrode A from the center of the core, and the outer periphery of the electrode assembly JR amplifies the stress applied to the core C side when the electrode assembly JR swells. outer and the outer periphery of the electrode assembly JR, the wound turn portion included in the second fan-shaped region surrounded by them amplifies the stress applied to the core C side when the electrode assembly JR swells. A,outer The reason is that the wound turn portion where the outer-periphery-side end B of the positive electrode B is located contains the most layers of the electrode and the separator in the radial direction. Therefore, when the electrode assembly JR swells, the wound turn portion where the outer-periphery-side end B of the positive electrode B is located and the outer-periphery-side end A of the negative electrode A adjacent to it

[0114] The reason is that the wound turn portion where the outer-periphery-side end B of the positive electrode B is located contains the largest number of layers of the electrode and the separator in the radial direction. Therefore, when the electrode assembly JR swells, the wound turn portion where the outer-periphery-side end B of the positive electrode B is located and the outer-periphery-side end A of the negative electrode A adjacent to it outer come into contact with the battery housing H earlier and are pressed the most compared to other outer peripheral regions, increasing the stress in the core C direction by the principle of action and reaction. outer come into contact with the battery housing H earlier and are pressed the most compared to other outer peripheral regions, increasing the stress in the core C direction by the principle of action and reaction. outer come into contact with the battery housing H earlier and are pressed the most compared to other outer peripheral regions, increasing the stress in the core C direction by the principle of action and reaction.

[0115] According to experiments, since the gap between the electrode assembly JR and the battery housing H is small, when the initial cycle is performed, the outer-periphery-side end B of the positive electrode B already outerThe winding turn portion where it is located begins to contact the inner wall of the battery housing H. Also, the outer peripheral side end B of the positive electrode B outer Once the winding turn portion where it is located begins to contact the battery housing H, as the swelling of the electrode assembly JR becomes more severe, the corresponding winding turn portion is gradually pushed toward the inner wall of the battery housing H. Therefore, if the usage cycle is repeated, the outer peripheral side end A of the negative electrode A outer and the outer peripheral side end B of the positive electrode B outer are fixed by the anchor effect and hardly rotate. Also, if the usage cycle is continuously repeated, the outer peripheral side end B of the positive electrode B outer The degree of pressing (compression) at the point becomes more serious, so the principle of action and reaction amplifies the stress at that point to the maximum.

[0116] Hereinafter, for convenience of explanation, the winding turn portion included in the first sector region is defined as the stress vulnerable region D1, and the winding turn portion included in the second sector region is defined as the stress amplification region D2.

[0117] According to still another form, while the cylindrical battery is repeatedly charged and discharged after shipment, the angles and positions of the stress vulnerable region D1 and the stress amplification region D2 change.

[0118] As an example, the cylindrical battery can be repeatedly charged and discharged up to the effective usage cycle. The effective usage cycle is the total number of cycles in which safe charging and discharging can be repeated from BOL (Beginning of Life, at the time of shipment) to EOL (End of Life, the life required by the customer company).

[0119] The effective usage cycle of the cylindrical battery can be designed in advance according to its usage purpose. In the embodiment, the effective usage cycle can be 200 cycles or more, 300 cycles or more, 400 cycles or more, 500 cycles or more, 600 cycles or more, 700 cycles or more, 800 cycles or more, 900 cycles or more, or more cycles.

[0120] Preferably, the cylindrical battery is designed to be able to stably exhibit its performance even when fully charged and fully discharged are repeated at least for a preset number of cycles, for example, for more than the effective use cycles, at least at normal temperature. Full charge means charging from the lower limit to the upper limit of the operating voltage, and full discharge means discharging from the upper limit to the lower limit of the operating voltage.

[0121] If the number of use cycles of the cylindrical battery increases to more than the effective use cycles, the corresponding cylindrical battery can be replaced with a new battery, reused for other purposes, or recycled for the recovery of the raw materials contained in the cylindrical battery.

[0122] Each cycle of the effective use cycles includes a full charge process and a full discharge process. Full charge and full discharge can be carried out at normal temperature, for example, 20°C to 40°C, preferably 20°C. Full charge is a charge that increases the charge state of the cylindrical battery from 0% to 100%. The magnitude of the charging current during full charge can be 1 / 4c to 1 / 3c, preferably 1 / 4c. Full discharge is a discharge that decreases the charge state of the cylindrical battery from 100% to 0%. The magnitude of the discharge current during full discharge can be 1 / 4c to 1 / 3c, preferably 1 / 3c. Here, the symbol c indicates the c-rate.

[0123] According to one form, the electrode assembly JR may have a winding structure in which at least the outer peripheral side end B of the positive electrode B in the stress amplification region D2 is separated from the inside of the stress vulnerable region D1 along the circumferential direction on the cross section of the electrode assembly JR. outer Here, the inside of the stress amplification region D2 means the inner region excluding its boundary.

[0124] According to another form, the electrode assembly JR may have a winding structure in which the stress amplification region D2 is separated from the stress vulnerable region D1 along the circumferential direction on the cross section of the electrode assembly JR.

[0125] In one embodiment, the electrode assembly JR can be designed from the beginning such that any one of the winding structures defined in the present invention is maintained while the cylindrical battery is repeatedly charged and discharged, for example, while it is charged and discharged more than the effective use cycles.

[0126] That is, the relative positions of the stress vulnerable region D1 and the stress amplification region D2 can be designed from the beginning by presetting the positions of the core side end A of the negative electrode A inner and the core side end B of the positive electrode B inner at the winding stage of the electrode assembly JR, and also the positions of the outer peripheral side end A of the negative electrode A outer and the outer peripheral side end B of the positive electrode B outer at the winding stage of the electrode assembly JR.

[0127] In one embodiment, the circumferential angle (central angle) corresponding to the core side end A of the negative electrode A inner and the core side end B of the positive electrode B inner |θ A,inner -θ B,inner | can be 30° or more and less than 180°.

[0128] Preferably, while the cylindrical battery is repeatedly charged and discharged, for example, while it is charged and discharged more than the effective use cycles, the central angle |θ A,inner -θ B,inner | can maintain an angle of 30° or more and less than 180°.

[0129] When designing the positions of the core side end A of the negative electrode A inner and the core side end B of the positive electrode B inner , the total rotation amount with respect to the ends of both electrodes (A inner , B inner ) can be considered. The total rotation amount can be determined in advance through the charge and discharge cycle test of the cylindrical battery. The total rotation amount can be the cumulative rotation amount when the cylindrical battery is charged and discharged more than the preset effective use cycles.

[0130] As a specific example, the central angle |θ A,inner -θ B,inner| can be 40° or less, 50° or less, 60° or less, 70° or less, 80° or less, 90° or less, 100° or less, 120° or less, 130° or less, 140° or less, 150° or less, 160° or less, 170° or less, or less than 180°.

[0131] Preferably, while the cylindrical battery is repeatedly charged and discharged, for example, while being charged and discharged more than the effective use cycle, the central angle |θ A,inner -θ B,inner | can maintain an angle of 40° or less, 50° or less, 60° or less, 70° or less, 80° or less, 90° or less, 100° or less, 120° or less, 130° or less, 140° or less, 150° or less, 160° or less, 170° or less, or less than 180° so that the core side end A of the negative electrode A inner and the core side end B of the positive electrode B inner can be preset at the winding stage of the electrode assembly JR.

[0132] As a preferred example, the central angle |θ A,inner -θ B,inner | can maintain an angle of 87° or more and less than 180° so that the core side end A of the negative electrode A inner and the core side end B of the positive electrode B inner can be preset at the winding stage of the electrode assembly JR while the cylindrical battery is repeatedly charged and discharged, for example, while being charged and discharged more than the effective use cycle.

[0133] In another embodiment, |θ inner corresponding to the circumferential angle (central angle) between the core side end A of the negative electrode A inner and the core side end B of the positive electrode B A,inner -θ B,inner | converges to a specific angle selected from the range of 30° or more and less than 180° while the cylindrical battery is repeatedly charged and discharged, for example, while being charged and discharged more than the effective use cycle, so that the core side end A of the negative electrode A inner and the core side end B of the positive electrode B inner can be preset at the winding stage of the electrode assembly JR.

[0134] As a specific example, the central angle |θA,inner -θ B,inner | While the cylindrical battery is repeatedly charged and discharged, for example, while it is charged and discharged more than the effective use cycle, between 30° and 40°, 40° and 50°, 50° and 60°, 60° and 70°, 70° and 80°, 80° and 90°, 90° and 100°, 100° and 110°, 110° and 120°, 120° and 130°, 130° and 140°, 140° and 150°, 150° and 160°, 160° and 170°, 170° and 180°, the core-side end A of the negative electrode A inner and the core-side end B of the positive electrode B inner The positions of can be preset at the winding stage of the electrode assembly JR.

[0135] As a preferred example, the central angle |θ A,inner -θ B,inner | While the cylindrical battery is repeatedly charged and discharged, for example, while it is charged and discharged more than the effective use cycle, in the range of 110° to 130°, more preferably 115° to 125°, more preferably converging to 120°, the core-side end A of the negative electrode A inner and the core-side end B of the positive electrode B inner The positions of can be preset at the winding stage of the electrode assembly JR.

[0136] As described above, the negative electrode A is longer in the winding direction than the positive electrode B, and the positive electrode B is located inside the negative electrode A in the winding direction. Therefore, the angle θ of the outer peripheral side end A of the negative electrode A outer of A,outer is the outer peripheral side end B of the positive electrode B outer of A,outer angle θ of

[0137] In the embodiment, the outer peripheral side end A of the negative electrode A outer angle θ of A,outer and the outer peripheral side end B of the positive electrode B outer angle θ of B,outer The central angle |θ corresponding to the difference between A,outer -θ B,outer | can be 10° or more and 90° or less.

[0138] Preferably, while the cylindrical battery is repeatedly charged and discharged, for example, while it is charged and discharged more than the effective use cycles, the central angle |θ A,outer -θ B,outer | can maintain an angle of 10° or more and 90° or less, and the outer peripheral side end A of the negative electrode A outer and the outer peripheral side end B of the positive electrode B outer can be preset at the winding stage of the electrode assembly JR.

[0139] When the electrode assembly JR bulges (during swelling), to relieve the stress imbalance applied to the core C side, the central angle |θ A,outer -θ B,outer | can be designed to be smaller than the central angle |θ A,inner -θ B,inner |.

[0140] As a specific example, the central angle |θ A,outer -θ B,outer | can have an angle of 80° - 90°, 70° - 80°, 60° - 70°, 50° - 60°, 40° - 50°, 30° - 40°, 20° - 30°, or 10° - 20°.

[0141] Preferably, the central angle |θ A,outer -θ B,outer | can maintain an angle of 80° - 90°, 70° - 80°, 60° - 70°, 50° - 60°, 40° - 50°, 30° - 40°, 20° - 30°, or 10° - 20° while the cylindrical battery is repeatedly charged and discharged, for example, while it is charged and discharged more than the effective use cycles, and the outer peripheral side end A of the negative electrode A outer and the outer peripheral side end B of the positive electrode B outer can be preset at the winding stage of the electrode assembly JR.

[0142] As a preferred example, the central angle |θ A,outer -θ B,outer | maintains an angle of 10° or more and 32° or less while the cylindrical battery is repeatedly charged and discharged, for example, while it is charged and discharged more than the effective use cycles, and the outer peripheral side end A of the negative electrode A outer and the outer peripheral side end B of the positive electrode B outerThe position can be preset during the winding stage of the electrode assembly JR.

[0143] In other embodiments, the central angle |θ A,outer -θ B,outer | converges to a specific angle selected from the range of 10° to 90° while the cylindrical battery is repeatedly charged and discharged, or for example, while it is charged and discharged more than the effective use cycles, so that the outer peripheral side end portion A outer of the negative electrode A outer and the outer peripheral side end portion B

[0144] of the positive electrode B A,outer -θ B,outer | converges to an angle of 80° to 90°, 70° to 80°, 60° to 70°, 50° to 60°, 40° to 50°, 30° to 40°, 20° to 30°, or 10° to 20° while the cylindrical battery is repeatedly charged and discharged, or for example, while it is charged and discharged more than the effective use cycles, so that the outer peripheral side end portion A outer of the negative electrode A outer and the outer peripheral side end portion B

[0145] As a more specific example, the central angle |θ A,outer -θ B,outer | maintains an angle of 10° to 40° or converges to a specific angle selected from 10° to 40° while the cylindrical battery is repeatedly charged and discharged, or for example, while it is charged and discharged more than the effective use cycles, so that the outer peripheral side end portion A outer of the negative electrode A outer and the outer peripheral side end portion B

[0146] FIG. 4 is a diagram for explaining the relative positional relationship between the stress vulnerable region D1 and the stress amplification region D2 according to an embodiment of the present invention.

[0147] Referring to FIG. 4, the first straight line L B,inner and the second straight line L A,innerAnd the stress vulnerable region D1 surrounded by the outer periphery of the electrode assembly JR corresponds to the first sector region and has a central angle (θ1). Also, the third straight line L B,outer , the fourth straight line L A,outer And the stress amplification region D2 surrounded by the outer periphery of the electrode assembly JR corresponds to the second sector region and has a central angle (θ2).

[0148] When a line segment that equally divides the central angle (θ1) of the stress vulnerable region D1 is defined as La, and a diameter line segment that is perpendicular to the line segment La and passes through the center of the core C of the electrode assembly JR is defined as O1O2, the cross section of the electrode assembly JR can be divided into a first semi-circular region CL1 and a second semi-circular region CL2 that face each other based on the diameter line segment O1O2.

[0149] While the cylindrical battery is repeatedly charged and discharged, for example, while it is charged and discharged more than the effective use cycles, the stress amplification region D2 hardly rotates, while the stress vulnerable region D1 can rotate in the clockwise direction.

[0150] While the cylindrical battery is repeatedly charged and discharged, for example, while it is charged and discharged more than the effective use cycles, the stress amplification region D2, particularly the outer peripheral side end B outer of the positive electrode B, as it gets closer to the stress vulnerable region D1 in the circumferential direction, the possibility of collapse of the core C in the stress vulnerable region D1 increases.

[0151] Therefore, while the cylindrical battery is repeatedly charged and discharged, for example, while it is charged and discharged more than the effective use cycles, even if the stress vulnerable region D1 rotates, the stress vulnerable region D1 is located within the first semi-circular region CL1, and the stress amplification region D2 is located in the second semi-circular region CL2, so that the core side end A inner of the negative electrode A and the core side end B inner of the positive electrode B, the outer peripheral side end A outer of the negative electrode A and the outer peripheral side end B outer of the positive electrode B can be preset at the winding stage of the electrode assembly JR.

[0152] According to such a design, while the cylindrical battery is repeatedly charged and discharged, it is possible to prevent the stress applied to the core C side in the stress vulnerable region D1 and the stress applied to the core C side in the stress amplification region D2 from increasing above the critical level while overlapping. Here, the critical level may be a stress level that induces the collapse of the core C in the stress vulnerable region D1.

[0153] Preferably, from the viewpoint of stress dispersion, the position of the stress amplification region D2 can be designed such that the stress applied to the core C side in the stress vulnerable region D1 and the stress applied to the core C side in the stress amplification region D2 are at least partially opposed.

[0154] Specifically, the stress amplification region D2 is, for example, during charging and discharging more than the effective use cycle while the cylindrical battery is repeatedly charged and discharged, the core side end portion A of the negative electrode A inner and the core side end portion B of the positive electrode B inner even when rotating, is located within the second semi-circular region CL2 defined with respect to the stress vulnerable region D1, and at least a part of the stress amplification region D2 forms point symmetry with the stress vulnerable region D1 around the core C * so as to overlap with the third sector region R inner the core side end portion A of the negative electrode A inner and the core side end portion B of the positive electrode B outer the outer peripheral side end portion A of the negative electrode A outer and the outer peripheral side end portion B of the positive electrode B can be preset at the winding stage of the electrode assembly JR.

[0155] In another form, the stress amplification region D2 is, for example, during charging and discharging more than the effective use cycle while the cylindrical battery is repeatedly charged and discharged, the core side end portion A of the negative electrode A inner and the core side end portion B of the positive electrode B inner even when rotating, is located within the second semi-circular region CL2 defined with respect to the stress vulnerable region D1, and the outer peripheral side end portion B of the positive electrode B outer is the third sector region R * so as to overlap with, the core side end portion A of the negative electrode A inner and the core side end portion B of the positive electrode B inner the outer peripheral side end portion A of the negative electrode A outer and the outer peripheral side end portion B of the positive electrode Bouter The position can be preset during the winding stage of the electrode assembly JR.

[0156] In still another form, during repeated charging and discharging of the cylindrical battery, for example, during charging and discharging more than the effective use cycles, while the core-side end A of the negative electrode A inner and the core-side end B of the positive electrode B inner rotate, it is located within the second semi-circular region CL2 defined based on the stress vulnerable region D1, and the stress amplification region D2 overlaps with the fifth straight line L * that bisects the central angle of the third sector region R * a In such a way that the core-side end A of the negative electrode A inner and the core-side end B of the positive electrode B inner and the outer peripheral side end A of the negative electrode A outer and the outer peripheral side end B of the positive electrode B outer The positions can be preset during the winding stage of the electrode assembly JR.

[0157] In still another form, during charging and discharging of the cylindrical battery, for example, during charging and discharging more than the effective use cycles, while the core-side end A of the negative electrode A inner and the core-side end B of the positive electrode B inner rotate, it is located within the second semi-circular region CL2 defined based on the stress vulnerable region D1, and the outer peripheral side end B of the positive electrode B outer is such that the fifth straight line L * that equally divides the central angle of the third sector region R * a In such a way that the core-side end A of the negative electrode A inner and the core-side end B of the positive electrode B inner and the outer peripheral side end A of the negative electrode A outer and the outer peripheral side end B of the positive electrode B outer The positions can be preset during the winding stage of the electrode assembly JR.

[0158] According to the design as described above, at least a part of the stress applied to the core C side in the stress amplification region D2 opposes the stress applied to the core C side in the stress vulnerable region D1. By improving the symmetry of the stress applied to the core C side, during repeated charging and discharging of the cylindrical battery, for example, during charging and discharging more than the effective use cycle, the collapse of the core C can be prevented or the collapse phenomenon of the core C can be alleviated.

[0159] On the other hand, during repeated charging and discharging of the cylindrical battery, the rotation amount of the stress vulnerable region D1 is large, especially at the core side end A of the negative electrode A inner The rotation amount of is larger than that of the core side end B of the positive electrode B inner and the stress amplification region D2 hardly rotates. Considering such a difference in rotation amount, by optimally designing the positional relationship between the first straight line to the fifth straight line in the circumferential direction of the electrode assembly JR, the collapse of the core can be prevented or alleviated.

[0160] Specifically, as shown in FIG. 4, the electrode assembly JR has a winding structure in which the third straight line L A,inner and the fourth straight line L * a are located between the second straight line L B,outer and the fifth straight line L A,outer with reference to the circumferential direction on the cross section of the electrode assembly JR.

[0161] As another example, the electrode assembly JR has a winding structure in which the fourth straight line L * a is located between the fifth straight line L B,inner and the first straight line L A,outer and the third straight line L A,outer is located between the fourth straight line L A,inner and the second straight line L B,outer with reference to the circumferential direction on the cross section of the electrode assembly JR.

[0162] As yet another example, the electrode assembly JR has a winding structure in which the fourth straight line L * a is located between the fifth straight line L B,inner and the first straight line LA,outer is located, and the fifth straight line L * a and the second straight line L A,inner and a third straight line L B,outer may have a winding structure located therebetween.

[0163] As yet another example, the electrode assembly JR may have a winding structure in which, with reference to the circumferential direction on the cross-section of the electrode assembly JR, the central angle between the first straight line L A,inner and the third straight line L B,outer is smaller than the central angle between the first straight line L B,inner and the fourth straight line L A,outer

[0164] On the other hand, different from the illustration of FIG. 4, the position of the core-side end portion A inner of the negative electrode A and the position of the core-side end portion B inner of the positive electrode B may be interchanged.

[0165] In this case, the electrode assembly JR may have a winding structure in which, with reference to the circumferential direction on the cross-section of the electrode assembly JR, the third straight line L B,inner and the fourth straight line L * a are located between the first straight line L B,outer and the fifth straight line L A,outer

[0166] As another example, the electrode assembly JR may have a winding structure in which, with reference to the circumferential direction on the cross-section of the electrode assembly JR, the fourth straight line L * a is located between the fifth straight line L A,inner and the second straight line L A,outer and the third straight line L A,outer is located between the fourth straight line L B,inner and the first straight line L B,outer

[0167] As yet another example, the electrode assembly JR may have a winding structure in which, with reference to the circumferential direction on the cross-section of the electrode assembly JR, the fourth straight line L * a is located between the fifth straight line L A,inner and the second straight line L A,outer and the third straight line L * ​​​a and a first straight line L B,inner and a third straight line L B,outer may have a winding structure located therebetween.

[0168] As yet another example, the electrode assembly JR, based on the circumferential direction in the cross-section of the electrode assembly JR, has a winding structure in which the central angle between the second straight line L B,inner and the third straight line L B,outer is larger than the central angle between the first straight line L A,inner and the fourth straight line L A,outer may have a winding structure with a large central angle between them.

[0169] Preferably, the winding structure of the electrode assembly JR described above can be maintained while being charged and discharged more than the effective use cycle as an example while the cylindrical battery is repeatedly charged and discharged. To meet such conditions, the core-side end A inner of the negative electrode A and the core-side end B inner of the positive electrode B, the outer peripheral side end A outer of the negative electrode A and the outer peripheral side end B outer of the positive electrode B can be preset at the winding stage of the electrode assembly JR.

[0170] According to yet another aspect of the present invention, depending on the relative positions of the core-side end A inner and the outer peripheral side end A outer of the negative electrode, the core-side end B inner and the outer peripheral side end B outer of the positive electrode B, the speed at which the outer peripheral region of the electrode assembly corresponding to the outer peripheral side end B outer of the positive electrode B contacts the inner peripheral surface of the battery housing can change.

[0171] Figs. 5a to 5c are cross-sectional views of a cylindrical battery showing three embodiments with respect to the relative positions of the core-side end A inner and the outer peripheral side end A outer of the negative electrode, the core-side end B inner and the outer peripheral side end B outer of the positive electrode B.

[0172] The electrode assembly JR shown in FIGS. 5a to 5c has specifications that can be used for a cylindrical battery with a form factor of 4680 (diameter: 46 mm, height: 80 mm).

[0173] When the cylindrical battery of FIG. 5a is in the BOL state, the core-side end A of the negative electrode A inner and the outer-periphery-side end B of the positive electrode B outer are located on the same line in the radial direction of the electrode assembly JR.

[0174] When the cylindrical battery of FIG. 5b is in the BOL state, the core-side end B of the positive electrode B inner and the outer-periphery-side end B of the positive electrode B outer are located on the same line in the radial direction of the electrode assembly JR.

[0175] When the cylindrical battery of FIG. 5c is in the BOL state, the stress amplification region D2 is located within the second semi-circular region CL2 defined based on the stress vulnerable region D1, and is positioned so as to overlap the approximate center of the sector region R * which forms point symmetry with the stress vulnerable region D1.

[0176] When the cylindrical batteries of FIG. 5a and FIG. 5b are repeatedly charged and discharged, when the volume of the negative electrode A increases by about 2.5%, the outer-periphery-side end B of the positive electrode B outer starts to contact the inner surface of the battery housing H.

[0177] On the other hand, when the cylindrical battery of FIG. 5c is repeatedly charged and discharged, when the volume of the negative electrode A increases by about 5%, the outer-periphery-side end B of the positive electrode B outer starts to contact the inner surface of the battery housing H.

[0178] As in the case of the cylindrical battery of FIG. 5c, the fact that the time when the outer-periphery-side end B of the positive electrode B outer contacts the inner surface of the battery housing H is delayed means that the circularity of the cross-section of the electrode assembly JR is relatively well maintained.

[0179] If the roundness of the cross-section of the electrode assembly is relatively well maintained, like the cylindrical battery in Fig. 5c, the possibility of core collapse can be reduced compared to the cylindrical batteries in Figs. 5a and 5b even when the charge and discharge cycles are increased.

[0180] Figs. 6a and 6b are drawings showing the tendency of core collapse according to the diameter of the hollow part existing in the core of the electrode assembly JR.

[0181] Referring to Figs. 6a and 6b, when the diameter of the core C is changed to 6 mm, 7 mm, and 8 mm, the possibility of core collapse increases as the diameter of the core C increases. This is because the smaller the radius of curvature, the greater the resistance to stress.

[0182] Preferably, the core diameter of the electrode assembly JR can be adjusted to 7 mm or less, 6.5 mm or less, preferably 6 mm or less. The core diameter of the electrode assembly JR can be adjusted to 3 mm or more in consideration of the size of the winding core used in the winding process and the welding process using the hollow part of the core.

[0183] Hereinafter, the influence of the relative arrangement of the stress vulnerable region D1 and the stress amplification region D2 in the circumferential direction of the electrode assembly on the roundness of the core of the electrode assembly will be described through a cycle test.

[0184] In the electrode assembly fabricated as a sample, the core-side end A of the negative electrode inner , the core-side end B of the positive electrode inner , the outer circumferential side end A of the negative electrode outer and the outer circumferential side end B of the positive electrode outer were adjusted under various conditions in the circumferential direction. The position design applied to each sample will be described in detail later using the CT cross-sectional photographs of the sample cylindrical battery.

[0185] First, the manufacturing method of the electrode assembly, the manufacturing method of the cylindrical battery, the conditions for initial activation, and the charge and discharge conditions in the usage cycles after initial activation, which are commonly applied to the samples, will be described.

[0186] <Manufacture of Sample Electrode Assembly> First, the positive electrode and the negative electrode were fabricated. The positive electrode has a structure in which a positive electrode active material is coated on both sides of an aluminum foil along the longitudinal direction (winding direction). The negative electrode has a structure in which a negative electrode active material is coated on both sides of a copper foil along the longitudinal direction (winding direction). The positive electrode and the negative electrode include uncoated plain portions along the long-side ends. The length, width, and thickness of the aluminum foil are 4015 mm, 65 mm, and 15 μm, respectively. The length, width, and thickness of the copper foil are 4103 mm, 70 mm, and 10 μm, respectively. The coating width and coating length of the positive electrode active material are 65 mm and 4015 mm, respectively. The coating width and coating length of the negative electrode active material are 70 mm and 4103 mm, respectively. As the positive electrode active material, lithium nickel manganese cobalt oxide doped with aluminum was used. As the negative electrode active material, a mixed negative electrode material in which natural graphite and artificial graphite are mixed at a weight ratio of 50:50 was used. The thickness of the positive electrode was designed to be 161 μm including the thickness of the active material coating layer and the thickness of the aluminum foil, and the thickness of the negative electrode was designed to be 189 μm including the thickness of the active material coating layer and the thickness of the copper foil. As the separator, a film in which an inorganic particle coating layer is formed on both sides of a porous polyethylene substrate was used, and the length, width, and thickness of the separator are 4235 mm, 72 mm, and 13 μm, respectively. Two separators were prepared. One separator was interposed between the positive electrode and the negative electrode, and the other separator was used as a winding film. The sample electrode assembly was fabricated by a known jelly roll winding process. In the sample electrode assembly, the winding turns of the positive electrode and the negative electrode are about 50 turns. The core, diameter, and height of the sample electrode assembly are 6 mm, 44.86 mm, and 73.3 mm, respectively.

[0187] <Fabrication of Sample Cylindrical Battery> The sample cylindrical battery was fabricated to have the cross-sectional structure shown in FIG. 32 described later. The outer diameter, thickness, and inner diameter of the battery housing are 46 mm, 0.45 mm, and 45.1 mm, respectively. A non-aqueous electrolyte in which 1.25 moles of lithium salt LiPF6 was added to a solvent in which EC / EMC / DMC was mixed at a volume ratio of 20 / 5 / 75 was injected into the sample cylindrical battery. The sample cylindrical battery has a capacity of 12.5 Ah and an operating voltage of 2.5 V to 4.2 V. The upper limit voltage is the full charge voltage, corresponding to a state of charge (SOC) of 100%. The lower limit voltage is the full discharge voltage, corresponding to a state of charge (SOC) of 0%.

[0188] <Setting of the initial state of the cycle> After injecting the electrolyte, an activation process was performed to activate the sample cylindrical battery. After activation, the state of charge of the sample cylindrical battery is 30%. The state of the cylindrical battery after full discharge following activation charging is regarded as the BOL (Beginning of Life) state. In the activation charging of the cylindrical battery, the magnitude of the charging current and the temperature were set to 1 / 4c and 20 °C, respectively. Here, c is a symbol indicating the C-rate of the current, and the same applies hereinafter. In the full discharge of the sample cylindrical battery, the magnitude of the discharge current and the temperature were set to (1 / 3c) and 20 °C, respectively.

[0189] <Taking a CT cross-sectional photograph of the BOL state, measuring the rotation angle of the electrode end portion, and the roundness of the core of the electrode assembly> For the sample cylindrical battery in the BOL state, a CT cross-sectional photograph was obtained by performing CT tomography using a Vtomex m300 device manufactured by General Electric. Then, from the CT cross-sectional photograph, the core-side end portion A of the negative electrode inner , the core-side end portion B of the positive electrode inner , the outer peripheral side end portion A of the negative electrode outer and the outer peripheral side end portion B of the positive electrode outerThe position was identified. Also, with reference to the center of the core of the electrode assembly, the angles of the stress vulnerable region D1 and the stress amplification region D2 along the circumferential direction, and the rotation amounts of the ends of the negative electrode and the ends of the positive electrode at the core and the outer periphery of the electrode assembly were measured. Further, when measuring the distances to the innermost electrode winding turns along the circumferential direction at 24 equally spaced intervals with reference to the center of the core from the CT cross-sectional photographs, the ratio (%) of the minimum value to the maximum value of the distances was calculated as the roundness value of the core of the electrode assembly. The roundness of the core of the electrode assembly is a measure for evaluating symmetry. If the roundness decreases, the shape of the core cannot maintain a circular shape and has a distorted shape. Also, if the roundness becomes lower than the critical level, the core cannot maintain its shape and may collapse as shown in Fig. 2c.

[0190] <Charge-discharge cycle conditions> The sample cylindrical battery in the BOL state was mounted on a cycler, and the cycle test was continuously repeated 300 times or more. The cycle of 300 times or more can be an example of an effective usage cycle. The cycle test was carried out with a limit of 3 times a day. One cycle includes a full charge process and a full discharge process. A 1-hour rest period was provided between the full charge process and the full discharge process. The temperature of the cycle test was set at 20°C. The magnitude of the charging current during full charge was set at 1 / 4c and charged for 4 hours, and the magnitude of the discharging current during full discharge was set at 1 / 3c and discharged for 3 hours. The voltage of the sample cylindrical battery during full charge increased from 2.5V to 4.2V, and the voltage of the sample cylindrical battery during full discharge decreased from 4.2V to 2.5V.

[0191] <Taking CT cross-sectional photographs after the cycle test, measuring the rotation angles of the electrode ends and the roundness of the core of the electrode assembly> For the sample cylindrical battery that had undergone a cycle test a predetermined number of times, CT tomography was performed using the above-mentioned apparatus to obtain CT cross-sectional photographs. Then, from the CT cross-sectional photographs, the core-side end A of the negative electrode inner , the core-side end B of the positive electrode inner , the outer periphery-side end A of the negative electrode outer and the outer periphery-side end B of the positive electrode outerThe position was identified. Also, based on the center of the core of the electrode assembly, the angles of the stress vulnerable region D1 and the stress amplification region D2, and the rotation amounts of the ends of the negative electrode and the ends of the positive electrode at the core and the outer periphery of the electrode assembly were measured. Further, when the distance to the innermost electrode winding turn based on the center of the core was measured at 24 equally spaced intervals along the circumferential direction from the CT cross-sectional photograph, the ratio (%) of the minimum value to the maximum value of the distance was calculated as the roundness value of the core of the electrode assembly.

[0192] <Cycle Test for the 1st Sample Cylindrical Battery> Fig. 7a is a CT cross-sectional photograph taken when the cylindrical battery manufactured as the 1st sample (hereinafter referred to as the 1st sample battery) is in the BOL state, Fig. 7b is a CT cross-sectional photograph taken after performing 200 cycle tests on the 1st sample battery, and Fig. 7c is a CT cross-sectional photograph taken after performing 300 cycle tests on the 1st sample battery.

[0193] Referring to Figs. 7a to 7c, on the CT cross-sectional photograph, the positive electrode and the negative electrode are wound in the clockwise direction, and the negative electrode is wound earlier than the positive electrode. Therefore, based on the center of the core of the electrode assembly, the negative electrode is arranged closer to the center than the positive electrode. The winding directions of the positive electrode and the negative electrode are determined by the standing direction of the cylindrical battery at the time of taking the CT cross-sectional photograph. If the standing direction of the cylindrical battery is reversed, the winding directions of the electrodes appearing in the CT cross-sectional photograph may be opposite.

[0194] When the 1st sample battery is in the BOL state, the angle of the stress vulnerable region D1 between the core-side end A of the negative electrode inner and the core-side end B of the positive electrode inner was measured to be 160.89°, and the angle of the stress amplification region D2 between the outer periphery-side end A of the negative electrode outer and the outer periphery-side end B of the positive electrode outer was measured to be 31.71°. Also, the roundness of the core of the electrode assembly was calculated to be 89.9%.

[0195] When the first sample battery was subjected to 200 cycle tests, the angle of the stress vulnerable region D1 between the core side end A of the negative electrode inner and the core side end B of the positive electrode inner was measured to be 175.55°, and the angle of the stress amplification region D2 between the outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer was measured to be 30.58°.

[0196] The core side end A of the negative electrode inner and the core side end B of the positive electrode inner rotated in the counterclockwise direction when compared with the BOL state. The rotation amount of the core side end A of the negative electrode inner was relatively larger than the rotation amount of the core side end B of the positive electrode inner As a result, the angle of the stress vulnerable region D1 increased by 14.66° compared with the BOL state.

[0197] The outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer hardly rotated when compared with the BOL state. In the measurement, the angle of the stress amplification region D2 decreased by 1.13° compared with the BOL state. Since there is an influence of the operator's manual error during the angle measurement, the decrease in the angle of the stress amplification region D2 is not at a significant level.

[0198] On the other hand, when the CT cross-sectional photograph was divided into a first semi-circular region CL1 and a second semi-circular region CL2 based on the diameter line segment O1O2 passing through the center of the core of the electrode assembly and perpendicular to the straight line that bisects the central angle of the stress vulnerable region D1 into equal angles, the stress vulnerable region D1 and the stress amplification region D2 maintained their positions continuously within the first semi-circular region CL1 and the second semi-circular region CL2, respectively, during the progress of 200 cycles of charge and discharge.

[0199] Also, the stress amplification region D2 maintained its position within the second semi-circular region CL2 defined based on the stress vulnerable region D1 during the progress of 200 cycles of charge and discharge, and a fan-shaped region R * symmetric to the stress vulnerable region D1 with respect to the center of the core and the bisecting line segment L * aIt was continuously maintained in a state of being superimposed.

[0200] After 200 charge-discharge cycles were performed, the roundness of the core of the electrode assembly was calculated to be 89.7%, showing a decrease of only 0.2% compared to the roundness of 89.9% in the BOL state, with no substantial change.

[0201] When the 1st sample battery was subjected to 300 cycle tests, at the core side end A of the negative electrode inner and the core side end B of the positive electrode inner the angle of the stress vulnerable region D1 between them was measured to be 178.49°, and at the outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer the angle of the stress amplification region D2 between them was measured to be 30.77°.

[0202] The core side end A of the negative electrode inner and the core side end B of the positive electrode inner were further rotated in the counterclockwise direction compared to the state after 200 cycles. Since the rotation amount of the core side end A of the negative electrode inner was relatively larger than that of the core side end B of the positive electrode inner the angle of the stress vulnerable region D1 increased by 2.94° compared to the state after 200 cycles.

[0203] The outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer showed no substantial change compared to the state after 200 cycles. As the number of cycles increased to a certain extent, an anchor effect occurred where the outer peripheral surface of the electrode assembly where the outer peripheral side end B of the positive electrode outer was located was firmly adhered to the inner surface of the battery housing and its position was fixed. Therefore, the angle of the stress amplification region D2 showed little change compared to the state after 200 cycles.

[0204] The positions of the stress vulnerable region D1 and the stress amplification region D2 were continuously maintained within the first semi-circular region CL1 and the second semi-circular region CL2, respectively, even during the progress of 300 charge-discharge cycles. Further, the stress amplification region D2 maintained its position within the second semi-circular region CL2 defined based on the stress vulnerable region D1 during the progress of 300 charge-discharge cycles, and was a sector region R that was point-symmetrical with the stress vulnerable region D1 with respect to the center of the core. * of the bisecting line segment L * a and continuously maintained a superimposed state.

[0205] After 300 charge-discharge cycles were performed, the roundness of the core of the electrode assembly was calculated to be 89.7%, and there was no change compared to the roundness of 89.7% after 200 cycles.

[0206] There was almost no change in the roundness calculated in the BOL state, after 200 cycles, and after 300 cycles. Also, the relative positional relationship of the above-described first to fifth straight lines was maintained identically during the repetition of the cycle test. The arrangement design of the stress vulnerable region D1 and the stress amplification region D2 applied to the No. 1 sample battery is effective in preventing or mitigating the collapse of the core in the effective use cycles of at least 200 cycles or more or 300 cycles or more by maintaining the circularity of the core of the electrode assembly and dispersing the stress.

[0207] <Cycle Test for the No. 2 Sample Cylindrical Battery> Fig. 8a is a CT cross-sectional photograph taken when the cylindrical battery (hereinafter referred to as the No. 2 sample battery) manufactured as the No. 2 sample is in the BOL state, and Fig. 8b is a CT cross-sectional photograph taken after performing 900 cycle tests, which is considerably more than those in Example 1, on the No. 2 sample battery.

[0208] Referring to Figs. 8a and 8b, on the CT cross-sectional photograph, the positive electrode and the negative electrode are wound in the clockwise direction, and the negative electrode is wound first than the positive electrode. Therefore, the negative electrode is arranged closer to the center of the core of the electrode assembly than the positive electrode.

[0209] When the second sample battery is in the BOL state, the core-side end A of the negative electrode inner and the core-side end B of the positive electrode inner The angle of the stress-vulnerable region D1 between them was measured to be 109.95°, and the outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer The angle of the stress amplification region D2 between them was measured to be 14.56°. Also, the roundness of the core of the electrode assembly was calculated to be 93.04%.

[0210] When the second sample battery was continuously subjected to 900 cycle tests, the core-side end A of the negative electrode inner and the core-side end B of the positive electrode inner The angle of the stress-vulnerable region D1 between them was measured to be 133.31°, and the outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer The angle of the stress amplification region D2 between them was measured to be 13.47°.

[0211] The core-side end A of the negative electrode inner and the core-side end B of the positive electrode inner Rotated significantly in the counterclockwise direction when compared with the BOL state. The rotation amount of the core-side end A of the negative electrode inner is relatively larger than the rotation amount of the core-side end B of the positive electrode inner As a result, the angle of the stress-vulnerable region D1 increased by 23.36° compared with the BOL state.

[0212] The outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer Hardly rotated when compared with the BOL state. In the measurement, the angle of the stress amplification region D2 decreased slightly compared with the BOL state. However, since there is an influence of the operator's manual error during the angle measurement, the decrease in the angle of the stress amplification region D2 is not significant.

[0213] On the other hand, based on the diameter line segment O1O2 passing through the center of the core of the electrode assembly and perpendicular to the straight line that equally divides the central angle of the stress-vulnerable region D1, the CT cross-sectional photograph can be divided into a first semi-circular region CL1 and a second semi-circular region CL2.

[0214] The stress vulnerability region D1 maintained its position continuously within the first semi-circular region CL1 even during the progress of 900 charge-discharge cycles.

[0215] The stress amplification region D2 was located within the second semi-circular region CL2 at the initial stage of the cycle test. As the cycle test progressed to the middle stage, the stress vulnerability region D1 rotated counterclockwise and moved to the first semi-circular region CL1. Also, the stress amplification region D2 began to overlap with the stress vulnerability region D1 in the second half of the cycle test. After 900 cycles, the outer peripheral side end B outer of the positive electrode became substantially identical to the position of the core side end A inner of the negative electrode. As the number of cycles increased, the core side end A inner of the negative electrode rotated counterclockwise. Therefore, the central angle between the core side end A inner of the negative electrode and the outer peripheral side end B outer of the positive electrode gradually decreased. Thus, in the case of the outer peripheral side end B outer of the positive electrode, it was separated counterclockwise along the circumferential direction from the stress vulnerability region D1 before 900 cycles. If the cycle test is further repeated beyond 900 cycles, it is expected to be located within the stress vulnerability region D1, and all of the stress amplification region D2 will overlap with the stress vulnerability region D1.

[0216] After 900 charge-discharge cycles were performed, the roundness of the core of the electrode assembly was calculated to be 92.10%, which was a decrease of only 0.94% compared to the roundness of 93.04% in the BOL state. Considering that the number of cycles reached 900, such a decrease in roundness is not a significant level of decrease.

[0217] The results of the experiment on the second sample battery confirm that when the relative positions of the stress vulnerability region D1 and the stress amplification region D2 in the circumferential direction are intentionally designed according to the embodiments of the present invention, it is effective in maintaining the roundness of the core of the electrode assembly.

[0218] That is, by taking into account in advance the amount of rotation of the electrode end due to the increase in the cycle, during the progress of 900 cycles, the stress amplification region D2, particularly the outer peripheral side end B of the positive electrode outer If the position of the electrode end is designed from the beginning so that the circumferential position of

[0219] Figure 9 shows the negative electrode core side end A while repeating the cycle test from immediately after manufacturing for the second sample battery inner and the positive electrode core side end B inner is a graph showing the measurement results of the amount of rotation.

[0220] Referring to Figure 9, in the second sample battery, the amount of rotation of the negative electrode core side end A inner and the positive electrode core side end B inner shows a pattern of gradually increasing as the number of cycles increases. The amount of rotation of the negative electrode core side end A inner and the positive electrode core side end B inner is the largest in the activation cycle section. The amount of rotation of the negative electrode core side end A inner and the positive electrode core side end B inner shows a linearly increasing pattern in the cycle repetition section after the activation cycle. In the case of the second sample battery, after 900 cycles, the negative electrode core side end A inner and the positive electrode core side end B inner were measured to have rotation amounts of 77.9° and 40°, respectively. On the other hand, referring to the partial enlarged view of the local area of the graph, when one cycle test is performed, the amount of rotation of the negative electrode core side end A inner gradually increases while showing a pattern of increasing during the full charge process and then decreasing during the full discharge process. Conversely, the amount of rotation of the positive electrode core side end B inner gradually increases while showing a pattern of decreasing during the full charge process and then increasing during the full discharge process.

[0221] The test results of the second sample battery confirm that even if the first sample battery is subjected to more than 900 cycle tests, the change in roundness should not be significant. In the second sample battery, when in the BOL state, the stress vulnerable region D1 and the stress amplification region D2 are separated by approximately 63.34° in the circumferential direction. However, in the first sample battery, even after 300 cycles, the stress vulnerable region D1 and the stress amplification region D2 are separated by 71.71°, which is greater than 63.34° in the circumferential direction. Therefore, even if additional charge-discharge tests are performed on the first sample battery from 300 cycles to 900 cycles, due to the linear increasing trend of the electrode rotation, the outer peripheral side end B of the positive electrode outer should not overlap with the inner region of the stress vulnerable region D1. Thus, similar to the test results of the second sample battery, it is obvious to those skilled in the art that the roundness of the core of the electrode assembly should not decrease to the extent that it causes the collapse of the core.

[0222] <Cycle Test on the Third Sample Cylindrical Battery> FIG. 10a is a CT cross-sectional photograph taken when the cylindrical battery manufactured as the third sample (hereinafter referred to as the third sample battery) is in the BOL state, and FIG. 10b is a CT cross-sectional photograph taken after 900 cycle tests are performed on the third sample battery.

[0223] Referring to FIGS. 10a and 10b, on the CT cross-sectional photograph, the positive electrode and the negative electrode are wound in the clockwise direction, and since the negative electrode is wound before the positive electrode, the negative electrode is located inside the electrode assembly in the centripetal direction with respect to the positive electrode.

[0224] In the third sample battery, when in the BOL state, the angle of the stress vulnerable region D1 between the core side end A of the negative electrode inner and the core side end B of the positive electrode inner is measured to be 90.67°, and the angle of the stress amplification region D2 between the outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer is measured to be 16.59°. Also, the roundness of the core of the electrode assembly is calculated to be 93.23%.

[0225] When the third sample battery was continuously subjected to 900 cycle tests, the angle of the stress vulnerable region D1 between the core side end A of the negative electrode inner and the core side end B of the positive electrode inner was measured to be 110.52°, and the angle of the stress amplification region D2 between the outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer was measured to be 16.14°.

[0226] The core side end A of the negative electrode inner and the core side end B of the positive electrode inner rotated significantly in the counterclockwise direction when compared with the BOL state. The rotation amount of the core side end A of the negative electrode inner was relatively larger than the rotation amount of the core side end B of the positive electrode inner As a result, the angle of the stress vulnerable region D1 increased by 19.85° compared with the BOL state.

[0227] The outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer hardly rotated when compared with the BOL state. In the measurement, the angle of the stress amplification region D2 decreased slightly compared with the BOL state. Since there is an influence of the operator's manual error during the angle measurement, the angle decrease of the stress amplification region D2 is not at a significant level.

[0228] On the other hand, based on the diameter line segment O1O2 passing through the center of the core of the electrode assembly and perpendicular to the straight line that equally divides the central angle of the stress vulnerable region D1, the CT cross-sectional photograph can be divided into a first semi-circular region CL1 and a second semi-circular region CL2.

[0229] The position of the stress vulnerable region D1 was continuously maintained within the first semi-circular region CL1 even during the progress of 900 cycles of charge and discharge.

[0230] The stress amplification region D2 overlapped with the stress vulnerable region D1 from the BOL state, and even after 900 cycles, a part of the stress amplification region D2, particularly the outer peripheral side end B of the positive electrode outerThe circumferential position overlaps with the stress vulnerable region D1. The layout design of the stress vulnerable region D1 and the stress amplification region D2 applied to the third sample battery is not suitable for the embodiments of the present invention.

[0231] After 900 charge and discharge cycles, the roundness of the core of the electrode assembly was calculated to be 89.65%, which was a decrease of 3.58% compared to the roundness of 93.23% in the BOL state. Such a decrease in roundness is a significant level of decrease compared to the first sample battery and the second sample battery. Therefore, the electrode winding turns in the 3 o'clock to 6 o'clock direction on the CT cross-sectional photograph obtained after 900 cycles are deformed in curvature to a visually recognizable extent. Therefore, if the second sample battery is further charged and discharged more than 900 times, the core is likely to collapse.

[0232] The results of the cycle test on the third sample battery confirm that if the positions of the stress vulnerable region D1 and the stress amplification region D2 in the circumferential direction of the electrode assembly are not intentionally designed according to the embodiments of the present invention, the circularity of the core of the electrode assembly cannot be maintained.

[0233] That is, considering the linear increase in the rotational amount of the core side end of the positive electrode and the core side end of the negative electrode with the increase in cycles, during the progress of 900 cycles, the stress amplification region D2, especially the outer peripheral side end B of the positive electrode outer If the electrode positions in the electrode assembly are not initially designed so that the circumferential position of is not included in the stress vulnerable region D1, the roundness of the core of the electrode assembly cannot be maintained when the charge and discharge cycles are repeated more than 900 times. As a result, it is impossible to prevent or mitigate the phenomenon that the core of the electrode assembly collapses while the cylindrical battery is charged and discharged more than the effective use cycle.

[0234] <Cycle Test on the Fourth Sample Cylindrical Battery> FIG. 11a is a CT cross-sectional photograph taken when a cylindrical battery (hereinafter referred to as the 4th sample battery) manufactured as the 4th sample is in the BOL state, and FIG. 11b is a CT cross-sectional photograph taken after performing 700 cycle tests on the 4th sample battery.

[0235] Referring to FIGS. 11a and 11b, on the CT cross-sectional photograph, the positive electrode and the negative electrode are wound in the clockwise direction, and since the negative electrode is wound earlier than the positive electrode, the negative electrode is located inside the electrode assembly in the centripetal direction with respect to the positive electrode.

[0236] In the 4th sample battery, when in the BOL state, the core-side end A of the negative electrode inner and the core-side end B of the positive electrode inner the angle of the stress vulnerable region D1 between them was measured to be 87.43°, and the outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer the angle of the stress amplification region D2 between them was measured to be 19.5°. Also, the roundness of the core of the electrode assembly was calculated to be 95.24%.

[0237] In the 4th sample battery, when 700 cycle tests were continuously performed, the core-side end A of the negative electrode inner and the core-side end B of the positive electrode inner the angle of the stress vulnerable region D1 between them was measured to be 101.81°, and the outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer the angle of the stress amplification region D2 between them was measured to be 16.2°.

[0238] The core-side end A of the negative electrode inner and the core-side end B of the positive electrode inner rotated significantly in the counterclockwise direction when compared with the BOL state. The rotation amount of the core-side end A of the negative electrode inner is relatively larger than the rotation amount of the core-side end B of the positive electrode inner As a result, the angle of the stress vulnerable region D1 increased by 14.38° compared with the BOL state.

[0239] The outer peripheral side end A of the negative electrode outerand the outer peripheral side end B of the positive electrode outer has hardly rotated when compared with the BOL state. In the measurement, the angle of the stress amplification region D2 decreased by 3.3° compared with the BOL state.

[0240] On the other hand, based on the diameter line segment O1O2 passing through the center of the core of the electrode assembly and perpendicular to the straight line that bisects the central angle of the stress vulnerable region D1 into two equal angles, the CT cross-sectional photograph can be divided into a first semi-circular region CL1 and a second semi-circular region CL2.

[0241] The stress vulnerable region D1 maintained its position continuously within the first semi-circular region CL1 even during 700 cycles of charge and discharge.

[0242] The stress amplification region D2 overlaps with the stress vulnerable region D1 from the BOL state, but is located in the second semi-circular region CL2 without overlapping with the stress vulnerable region D1 after 700 cycles. The stress amplification region D2 initially maintained a state of overlapping with the stress vulnerable region D1 in the circumferential direction during the 700-cycle test. The stress amplification region D2 is separated from the stress vulnerable region D1 in the circumferential direction from the middle stage and enters the second semi-circular region CL2 in the latter half. The arrangement of the stress vulnerable region D1 and the stress amplification region D2 applied to the 4th sample battery is not suitable for the embodiment of the present invention. This is because the stress vulnerable region D1 and the stress amplification region D2 overlap until a considerable number of cycles progress from the BOL state, and stress is concentrated on the core of the electrode assembly.

[0243] After 700 cycles of charge and discharge were performed, the roundness of the core of the electrode assembly was calculated to be 87.86%, which is a decrease of 7.38% compared to the roundness of 95.24% in the BOL state. Such a decrease in roundness is a significant level of decrease compared to the 1st sample battery and the 2nd sample battery. Due to the decrease in roundness, the electrode winding turns in the 9 o'clock to 1 o'clock direction on the CT cross-sectional photograph obtained after 700 cycles are deformed in curvature to a recognizable extent by visual inspection. Therefore, when the 4th sample battery is further charged and discharged more than 700 times, the possibility of core collapse is high.

[0244] The results of the cycle test on the 4th sample battery confirm that if the positions of the stress vulnerable region D1 and the stress amplification region D2 in the circumferential direction of the electrode assembly are not intentionally designed according to the embodiment of the present invention, the circularity of the core of the electrode assembly cannot be maintained.

[0245] That is, considering the linear increase in the amount of rotation of the core side end of the positive electrode and the core side end of the negative electrode with the increase in the number of cycles, during the progress of 700 cycles, in the stress amplification region D2, especially at the outer peripheral side end B of the positive electrode outer If the electrode positions in the electrode assembly are not initially designed so that the circumferential position of B is not included in the stress vulnerable region D1, the roundness of the core of the electrode assembly cannot be maintained when the charge and discharge cycle is repeated 700 times or more. As a result, it is impossible to prevent or mitigate the phenomenon that the core of the electrode assembly collapses while charging and discharging the cylindrical battery more than the effective use cycle.

[0246] <Cycle Test on the 5th Sample Cylindrical Battery> FIG. 12a is a CT cross-sectional photograph taken when the cylindrical battery (hereinafter referred to as the 5th sample battery) manufactured as the 5th sample is in the BOL state, and FIG. 12b is a CT cross-sectional photograph taken after performing a cycle test of 420 cycles on the 5th sample battery.

[0247] Referring to FIGS. 12a and 12b, on the CT cross-sectional photograph, the positive electrode and the negative electrode are wound in the clockwise direction, and since the negative electrode is wound earlier than the positive electrode, the negative electrode is located inside the electrode assembly in the centripetal direction with respect to the positive electrode.

[0248] In the 5th sample battery, when in the BOL state, the angle of the stress vulnerable region D1 between the core side end A of the negative electrode inner and the core side end B of the positive electrode inner was measured to be 104.79°, and the angle of the stress amplification region D2 between the outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer was measured to be 17.9°. In addition, the roundness of the core of the electrode assembly was calculated to be 92.65%.

[0249] When the fifth sample battery was continuously subjected to 420 cycle tests, the core side end A of the negative electrode inner and the core side end B of the positive electrode inner The angle of the stress vulnerable region D1 between them was measured to be 129.38°, and the outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer The angle of the stress amplification region D2 between them was measured to be 15.72°.

[0250] The core side end A of the negative electrode inner and the core side end B of the positive electrode inner Rotated in the counterclockwise direction at a significant level when compared with the BOL state. The core side end A of the negative electrode inner The amount of rotation of was relatively larger than that of the core side end B of the positive electrode inner As a result, the angle of the stress vulnerable region D1 increased by 24.59° compared with the BOL state.

[0251] The outer peripheral side end A of the negative electrode outer and the outer peripheral side end B of the positive electrode outer Hardly rotated when compared with the BOL state. In the measurement, the angle of the stress amplification region D2 decreased by 2.18° compared with the BOL state.

[0252] On the other hand, based on the diameter line segment O1O2 passing through the center of the core of the electrode assembly perpendicular to the straight line that equally divides the central angle of the stress vulnerable region D1, the CT cross-sectional photograph can be divided into a first semi-circular region CL1 and a second semi-circular region CL2.

[0253] The position of the stress vulnerable region D1 was continuously maintained within the first semi-circular region CL1 even during the progress of 420 cycles of charge and discharge.

[0254] The stress amplification region D2 began to overlap with the stress vulnerable region D1 from the middle stage of the cycle and completely overlapped with the stress vulnerable region D1 after 420 cycles. The arrangement of the stress vulnerable region D1 and the stress amplification region D2 applied to the 5th sample battery is not suitable for the embodiments of the present invention. This is because stress concentrates on the core of the electrode assembly while the stress vulnerable region D1 and the stress amplification region D2 overlap from the middle stage to the latter stage of the cycle.

[0255] After 420 charge and discharge cycles were performed, the roundness of the core of the electrode assembly was calculated to be 90.63%, which was a decrease of about 2.02% compared to the roundness of 92.65% in the BOL state. Such a decrease in roundness is a significant level of decrease compared to the 1st sample battery and the 2nd sample battery. Due to the decrease in roundness, the curvature of the electrode winding turns in the 3 o'clock to 7 o'clock direction on the CT cross-sectional photograph obtained after 420 cycles was deformed to a visually recognizable degree. Therefore, if the 5th sample battery is further charged and discharged more than 420 times, the possibility of core collapse is high.

[0256] The results of the cycle test on the 5th sample battery confirm that if the positions of the stress vulnerable region D1 and the stress amplification region D2 in the circumferential direction of the electrode assembly are not intentionally designed according to the embodiments of the present invention, the circularity of the core of the electrode assembly cannot be maintained.

[0257] That is, considering the linear increase in the rotational amount of the core-side end of the positive electrode and the core-side end of the negative electrode with the increase in the cycle, during the progress of 420 cycles, the stress amplification region D2, especially the outer peripheral side end B of the positive electrode outer If the electrode positions in the electrode assembly are not designed from the beginning so that the circumferential position of is not included in the stress vulnerable region D1, the roundness of the core of the electrode assembly cannot be maintained when the charge and discharge cycles are repeated 420 times or more. As a result, it is impossible to prevent or mitigate the phenomenon of the core of the electrode assembly collapsing while charging and discharging the cylindrical battery more than the effective use cycle.

[0258] <Cycle Test on the 6th Sample Cylindrical Battery> Figure 13a is a CT cross-sectional photograph taken when a cylindrical battery (hereinafter referred to as the No. 6 sample battery) manufactured as the No. 6 sample is in the BOL state, and Figure 13b is a CT cross-sectional photograph taken after performing 420 cycle tests on the No. 6 sample battery.

[0259] Referring to FIGS. 13a and 13b, on the CT cross-sectional photograph, the positive electrode and the negative electrode are wound in the clockwise direction, and since the negative electrode is wound earlier than the positive electrode, the negative electrode is located inside the electrode assembly in the centripetal direction with respect to the positive electrode.

[0260] In the No. 6 sample battery, when in the BOL state, the angle of the stress vulnerable region D1 between the core-side end A inner of the negative electrode and the core-side end B inner of the positive electrode was measured to be 125.73°, and the angle of the stress amplification region D2 between the outer peripheral side end A outer of the negative electrode and the outer peripheral side end B outer of the positive electrode was measured to be 16.4°. In addition, the roundness of the core of the electrode assembly was calculated to be 93.34%.

[0261] In the No. 6 sample battery, when 420 cycle tests were continuously performed, the angle of the stress vulnerable region D1 between the core-side end A inner of the negative electrode and the core-side end B inner of the positive electrode was measured to be 140.61°, and the angle of the stress amplification region D2 between the outer peripheral side end A outer of the negative electrode and the outer peripheral side end B outer of the positive electrode was measured to be 15.74°.

[0262] The core-side end A inner of the negative electrode and the core-side end B inner of the positive electrode rotated significantly in the counterclockwise direction when compared with the BOL state. The rotation amount of the core-side end A inner of the negative electrode was relatively larger than the rotation amount of the core-side end B inner of the positive electrode. As a result, the angle of the stress vulnerable region D1 increased by 14.88° compared with the BOL state.

[0263] The outer peripheral side end Aouter and the outer peripheral side end B of the positive electrode outer has hardly rotated when compared with the BOL state. The angle of the stress amplification region D2 decreased by 0.66° compared with the BOL state. Since there is an influence of manual error of the operator during the angle measurement, the decrease in the angle of the stress amplification region D2 is not at a significant level.

[0264] On the other hand, based on the diameter line segment O1O2 passing through the center of the core of the electrode assembly and perpendicular to the straight line that bisects the central angle of the stress vulnerable region D1 into two equal angles, the CT cross-sectional photograph can be divided into a first semi-circular region CL1 and a second semi-circular region CL2.

[0265] The position of the stress vulnerable region D1 was continuously maintained within the first semi-circular region CL1 even during the progress of 420 charge and discharge cycles.

[0266] The stress amplification region D2 began to overlap with the stress vulnerable region D1 from the middle cycle and completely overlapped with the stress vulnerable region D1 after 420 cycles. The arrangement of the stress vulnerable region D1 and the stress amplification region D2 applied to the 6th sample battery is not suitable for the embodiment of the present invention. This is because stress is concentrated on the core of the electrode assembly while the stress vulnerable region D1 and the stress amplification region D2 overlap from the middle cycle to the latter half cycle.

[0267] After 420 charge and discharge cycles were performed, the roundness of the core of the electrode assembly was calculated to be 87.15%, which was a decrease of 6.19% compared with the roundness of 93.34% in the BOL state. Such a decrease in roundness is a decrease at a more significant level than that of the 1st sample battery and the 2nd sample battery. Due to the decrease in roundness, the electrode winding turns in the 3 o'clock to 7 o'clock direction on the CT cross-sectional photograph obtained after 420 cycles are deformed in curvature to a visually recognizable degree. Therefore, when the 6th sample battery is further charged and discharged more than 420 times, the possibility of core collapse is high.

[0268] The results of the cycle test on the 6th sample battery confirm that if the positions of the stress vulnerable region D1 and the stress amplification region D2 in the circumferential direction of the electrode assembly are not intentionally designed according to the embodiments of the present invention, the circularity of the core of the electrode assembly cannot be maintained.

[0269] That is, considering the linear increase in the rotational amount of the core side end of the positive electrode and the core side end of the negative electrode with the increase of the cycle, during the progress of 420 cycles, especially the outer peripheral side end B of the positive electrode outer in the circumferential direction is not included in the stress vulnerable region D1, the circularity of the core of the electrode assembly cannot be maintained when the charge and discharge cycles are repeated more than 420 times. As a result, the phenomenon that the core of the electrode assembly collapses during charge and discharge of the cylindrical battery beyond the effective use cycle cannot be prevented or alleviated.

[0270] As can be seen from the above charge and discharge cycle tests, when the electrode assembly has a structure wound in a jelly roll form, if the positions of the ends of the negative electrode and the positive electrode at the core and the outer periphery are intentionally designed from the beginning to suit the embodiments of the present invention, the circularity of the core of the electrode assembly can be maintained without significant change even when the cylindrical battery is charged and discharged more than 200 cycles, more than 300 cycles, more than 400 cycles, more than 700 cycles, and often up to 900 cycles.

[0271] In a cylindrical battery including an electrode assembly wound in a jelly roll form, the angles at which the ends of the positive electrode and the negative electrode rotate along the circumferential direction vary depending on various factors such as the positive electrode active material, the negative electrode active material, the diameter of the electrode assembly, the thicknesses of the positive electrode and the negative electrode, and the number of winding turns of the positive electrode and the negative electrode. Therefore, according to the present invention, the cylindrical battery can be designed and manufactured as follows.

[0272] First, determine the specifications for the cylindrical battery's standard (diameter and height), all materials involved in the electrochemical reaction, and the effective usage cycles. The effective usage cycles can be appropriately determined considering the application of the cylindrical battery. The effective usage cycles can be arbitrarily selected, such as 200 cycles or more, 300 cycles or more, 400 cycles or more, 500 cycles or more, 600 cycles or more, 700 cycles or more, 800 cycles or more, 900 cycles or more, etc. Subsequently, produce a sample cylindrical battery through a process well-known in the industry and activate the sample cylindrical battery to bring it to the BOL state.

[0273] Next, while conducting a charge-discharge cycle test on the sample cylindrical battery that exceeds the effective usage cycles, measure the amount of rotation of the electrode due to the cycle increase as shown in FIG. 9. The amount of rotation of the electrode can be determined by obtaining CT cross-sectional photographs of the cylindrical battery at regular cycle intervals during the progress of the cycle test and then analyzing the CT cross-sectional photographs.

[0274] Once the amount of rotation of the electrode associated with the increase in the number of cycles is determined, as the first winding design condition, determine the initial angles of the stress-vulnerable region and the stress-amplification region, and as the second winding design condition, ensure that during repeated charge and discharge of the cylindrical battery up to the effective usage cycles, the outer peripheral side end B of the positive electrode in the stress-amplification region outer does not overlap with the inner region of the stress-vulnerable region, and the initial separation angle between two sections in the circumferential direction can be determined.

[0275] Subsequently, wind the electrode assembly according to the determined winding design conditions, and use the wound electrode assembly to produce a cylindrical battery. The cylindrical battery produced in this way can maintain the roundness of the core of the electrode assembly without significant change even when repeatedly charged and discharged up to the effective usage cycles.

[0276] 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 industry.

[0277] As an example, the cathode active material may include an alkali metal compound represented by the general chemical formula A[A x M y O 2+z (A contains at least one element among Li, Na, and K; M contains 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 of x, y, z, and the components contained in M are selected so that the compound maintains electrical neutrality).

[0278] As another example, the cathode active material may be an alkali metal compound xLiM 1 O2-(1 - x)Li2M 2 O3 (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).

[0279] As yet another example, the cathode 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; a, x, y, z, M 1 、M 2 and M 3(The stoichiometric coefficients of the components contained therein are selected such that the compound maintains electrical neutrality), or it may be a lithium metal phosphate represented by Li3M2(PO4)3 [where M contains at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and Al].

[0280] Preferably, the positive electrode active material may include primary particles and / or secondary particles formed by aggregation of primary particles.

[0281] As an example, as the negative electrode active material, a carbon material, a lithium metal or a lithium metal compound, a silicon-based compound, tin or a tin compound, etc. may be used. Metal oxides such as TiO2 and SnO2 with a potential of less than 2V can also be used as the negative electrode active material. As the carbon material, both low-crystalline carbon and high-crystalline carbon can be used.

[0282] The negative electrode active material may include a silicon-based active material, and the silicon-based active material may include one or more selected from the group consisting of Si particles, silicon oxide (e.g., SiOx (0 < x < 2)), SiC, and Si alloys. As an example, the silicon-based active material (e.g., SiO) may be added at a content of 0.5% to 15%, 1% to 10%, 2% to 6%, or 2% to 5% based on the weight of the entire negative electrode active material. If the content of the silicon-based active material (e.g., SiO) is adjusted within the above numerical range, it is possible to manage the volume expansion of the negative electrode that affects the collapse of the core of the electrode assembly while increasing the capacity of the negative electrode through the addition of SiO to a controllable level.

[0283] As the separator, a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as a polyethylene homopolymer, a polypropylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., can be used alone or by laminating these. As another example, the separator can use a normal porous non-woven fabric, for example, a non-woven fabric made of high-melting glass fibers, polyethylene terephthalate fibers, etc.

[0284] 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 such that an interstitial volume exists between adjacent particles.

[0285] The inorganic particles may be composed of an inorganic substance having a dielectric constant of 5 or more. As a non-limiting example, the inorganic particles may include at least one substance selected from the group consisting of Pb(Zr,Ti)O3 (PZT), Pb 1-x La x ZR 1-y Ti y O3 (PLZT), PB(Mg3Nb 2 / 3 )O3 - PbTiO3 (PMN - PT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0286] The electrolyte may be a salt having a structure such as A + B - . Here, A + includes ions consisting of alkali metal cations such as Li + , Na + , K + , or combinations thereof. And B - includes F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , BF2C2O4 - , BC4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 -, (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - It contains any one or more anions selected from the group consisting of.

[0287] Furthermore, 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.

[0288] Hereinafter, the structures of the electrodes and electrode assemblies used in the production of the cylindrical battery according to one embodiment of the present invention will be described. Thereafter, the structure of the cylindrical battery according to one embodiment of the present invention will also be described in detail.

[0289] The designs of the electrodes, electrode assemblies, and cylindrical batteries described in the embodiments are effective in preventing or alleviating the collapse of the core of the electrode assembly, along with the position design of the ends of the electrodes described above. In particular, the welding structure of the current collector utilizing the bent surface area formed by bending the plain area of the positive electrode and / or the plain area of the negative electrode can reduce the rotational freedom of the electrodes near the core of the electrode assembly by firmly fixing the positions of the positive electrode and / or the negative electrode.

[0290] FIG. 14a is a plan view showing the structure of an electrode 40 according to a first embodiment of the present invention.

[0291] Referring to FIG. 14a, the electrode 40 of the first embodiment includes a current collector 41 made of a metal foil and an active material layer 42. The metal foil can be a conductive metal such as aluminum or copper and is appropriately selected according to the polarity of the electrode 40. 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 40 includes a plain area 43 at the long-side end in the winding direction (X-axis). The plain area 43 is a partial area of the current collector 41 that is not coated with the active material. The area of the current collector 41 where the active material layer 42 is formed may be referred to as the active material part.

[0292] In the electrode 40, the width of the active material part in the short-side direction of the current collector 41 can be 50 mm to 120 mm, and the length of the active material part 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 part can be 1.0% to 4.0%.

[0293] Preferably, in the electrode 40, the width of the active material part in the short-side direction of the current collector 41 can be 60 mm to 70 mm, and the length of the active material part 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 part can be 1.2% to 2.3%.

[0294] The ratio of the short side to the long side of the active material part is significantly smaller than 6% to 11%, which is the ratio of the long side to the short side of the active material part of the electrode used in a cylindrical battery having a form factor of 1865 or 2170.

[0295] Preferably, the current collector 41 has an elongation of 1.5% to 3.0% and a tensile strength of 25 gf / mm 2 ~35 kgf / mm 2 It can be. The elongation and tensile strength can be measured according to the measurement method of IPC-TM-650. The electrode 40 is manufactured by forming an active material layer 42 on the current collector 41 and then crimping. During crimping, the elongation of the plain part 43 region and the active material layer 42 region is different. Therefore, a swell occurs in the electrode 40 after crimping, and the swell becomes more severe as the electrode 40 becomes longer.

[0296] Optimization of the elongation and tensile strength with respect to the current collector 41 reduces the camber length after crimping to less than 20 mm when the length of the electrode 40 is at the 4 m level. The camber length is the maximum deflection amount of the electrode 40 in the winding direction (X-axis) when the swelled electrode 40 is expanded. The maximum deflection amount can be measured at the outer peripheral side terminal. Since the electrode 40 with optimized elongation and tensile strength of the current collector 41 has a short camber length, no meandering defect occurs during the notching operation of the plain part 43 and the winding process of the electrode 40.

[0297] The lower the elongation of the current collector 41, the easier it is to break. When the elongation of the current collector 41 is less than 1.5%, the rolling processability of the current collector 41 decreases, and when crimping the electrode 40 with the active material layer 42 coated on the current collector 41, there is a risk of wire breakage in the current collector 41. On the other hand, when the elongation of the current collector 41 exceeds 3.0%, the active material part of the electrode 40 is excessively stretched and the camber length increases significantly. When the tensile strength of the current collector 41 is less than 25 kgf / mm 2 or exceeds 35 kgf / mm 2 the electrode processability of the electrode 40 decreases.

[0298] The camber phenomenon is particularly problematic in the positive current collector made of aluminum foil. By using an aluminum foil with an elongation rate of 1.5% to 3.0% and a tensile strength of 25 kgf / mm 2 to 35 kgf / mm 2 as the current collector according to the present invention, the camber phenomenon can be suppressed. It is preferable to form an active material layer on such a current collector and use it as a positive electrode.

[0299] Preferably, an insulating coating layer 44 can be formed at the boundary between the active material layer 42 and the plain part 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 plain part 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 plain part 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 40. The insulating coating layer 44 contains a polymer resin and may contain an inorganic filler such as Al2O3. The portion of the current collector 41 covered by the insulating coating layer 44 can be regarded as a plain part because it is not an area coated with the active material layer.

[0300] The plain part 43 includes a core-side plain part B1 adjacent to the core side of the electrode assembly, an outer peripheral-side plain part B3 adjacent to the outer peripheral side of the electrode assembly, and an intermediate plain part B2 interposed between the core-side plain part B1 and the outer peripheral-side plain part B3.

[0301] The core-side plain part B1, the outer peripheral-side plain part B3, and the intermediate plain part B2 can be defined as the plain part of the region adjacent to the core side, the plain part of the region adjacent to the outer peripheral side, and the plain part of the other region excluding these when the electrode 40 is wound as a jelly-roll type electrode assembly, respectively.

[0302] Hereinafter, the core-side plain part B1, the outer peripheral-side plain part B3, and the intermediate plain part B2 are referred to as the first part, the second part, and the third part, respectively.

[0303] As an example, the first part B1 may be a plain portion of the electrode region including the innermost winding turn, and the second part may be a plain portion of the electrode region including the outermost winding turn. The winding turns can be counted based on the core-side end of the electrode assembly.

[0304] As another example, the boundary between B1 / B2 can be appropriately defined at a point where the height (or change pattern) of the plain 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.

[0305] The boundary between B2 / B3 can be defined at a point where the height (or change pattern) of the plain 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. Once the boundaries of B1 / B2 and B2 / B3 are specified, the third part B2 can be automatically specified.

[0306] If only the boundary of B1 / B2 is specified, the boundary of B2 / B3 can be appropriately selected at a point near the outer peripheral side of the electrode assembly. As an example, the second part can be defined as the plain portion of the electrode region constituting the outermost winding turn. On the other hand, if only the boundary of B2 / B3 is specified, the boundary of B1 / B2 can be appropriately selected at a point near the core side of the electrode assembly. As an example, the first part can be defined as the plain portion of the electrode region constituting the innermost winding turn.

[0307] It does not rule out the intervention of other structures between the first part B1 and the third part B2. Nor does it rule out the intervention of other structures between the third part B2 and the second part B3.

[0308] In the first embodiment, the height of the plain 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 is relatively lower than those of the first portion B1 and 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 those of the first portion B1 and the second portion B3.

[0309] FIG. 14b is a plan view showing the structure of the electrode 45 according to the second embodiment of the present invention.

[0310] Referring to FIG. 14b, the electrode 45 of the second embodiment is different from that of the first embodiment only in that the height of the second portion B3 gradually decreases toward the outer peripheral side, and the other configurations are substantially the same.

[0311] In a modified form, the second portion B3 can be deformed into a stepped shape (refer to the dotted line) in which the height decreases step by step.

[0312] FIG. 14c is a plan view showing the structure of the electrode 50 according to the third embodiment of the present invention.

[0313] Referring to FIG. 14c, in the electrode 50 of the third embodiment, 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 may be the same or different.

[0314] Preferably, the height of the third portion B2 can be in a stepped shape that gradually increases from the core side toward the outer peripheral side.

[0315] Patterns 1 to 7 are obtained by dividing the third portion B2 around the position where the height of the plain portion 43 changes. Preferably, the number of patterns, the height (length in the Y-axis direction), and the width (length in the X-axis direction) of each pattern can be adjusted so as to maximize the dispersion of stress during the bending process of the plain portion 43. The dispersion of stress is for preventing the plain portion 43 from being broken when it is bent toward the core side of the electrode assembly.

[0316] Width d of the first part B1 B1 is designed by applying the condition that it does not block the core of the electrode assembly when the pattern of the third part B2 is bent toward the core side. The core means a cavity existing at the winding center of the electrode assembly.

[0317] As an example, the width d of the first part B1 B1 can increase in proportion to the bending length of Pattern 1. The bending length corresponds to the height of the pattern based on the bending point of the pattern.

[0318] Preferably, the width d of the first part B1 B1 can be set such that the radial width of the winding turn formed by the first part B1 is equal to or greater than the bending length of Pattern 1. In a modified example, the width d of the first part B1 B1 can be set such that the value obtained by subtracting the radial width of the winding turn formed by the first part B1 from the bending length of Pattern 1 is less than 0 or equal to 10% of the core radius.

[0319] In a specific example, when the electrode 50 is used to manufacture an electrode assembly of a cylindrical battery with a form factor of 4680, the width d of the first part 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 Pattern 1.

[0320] In an example, the width of each pattern can be designed to constitute one or more winding turns of the electrode assembly.

[0321] In another example, the height of the third part B2 can be in a stepped shape that increases from the core side toward the outer peripheral side and then decreases.

[0322] In still another example, the second part B3 can be deformed to have the same structure as that of the second embodiment.

[0323] In yet another example, the pattern structure applied to the third portion B2 can be extended up to the second portion B3 (see the dotted line).

[0324] FIG. 14d is a plan view showing the structure of the electrode 60 according to the fourth embodiment of the present invention.

[0325] Referring to FIG. 14d, in the electrode 60 of the fourth embodiment, the height of the first portion B1 and the second portion B3 in the winding axis (Y-axis) direction is 0 or more, and is relatively lower than the third portion B2. Also, the height of the first portion B1 and the height of the second portion B3 in the winding axis (Y-axis) direction may be the same or different.

[0326] Preferably, at least a partial section of the third portion B2 may include a plurality of segmented pieces 61. The plurality of segmented pieces 61 may have heights that increase stepwise 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.

[0327] 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.

[0328] In the fourth embodiment, when bending the non-patterned 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 bottom of the cutting groove (G in FIG. 14e) between the divided sections 61 and the active material layer 42. This is because when the non-patterned portion 43 is bent, stress is concentrated near the bottom 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 bottom of the cutting groove 63 from being damaged by the stress generated during the bending process of the non-patterned 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 section 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 sections can have the gap varying individually, in group units, or in two or more group units along one direction parallel to the winding direction. The bottom 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 bottom 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 sections can have the separation distance varying 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 circuit between two electrodes with opposite polarities facing each other with the separator interposed therebetween, and can support the bending point when the divided section 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 bottom of the cutting groove 63.In one example, the end portion 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 bottom 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.

[0329] 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.

[0330] Preferably, the width and height of the divided segments belonging to the same divided segment group may be substantially the same.

[0331] In another form, 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.

[0332] In yet another form, 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.

[0333] In yet another form, the gap between the bottom 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.

[0334] In yet another embodiment, in the plurality of segment pieces, the gap between the bottom 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.

[0335] FIG. 14e is a diagram showing the definitions of the width D, height H, and separation pitch P of the trapezoidal segment piece 61.

[0336] Referring to FIG. 14e, the width D, height H, and separation pitch P of the segment piece 61 are designed to prevent the base portion 43 near the bending point from breaking when the base portion 43 is bent and to prevent abnormal deformation of the base portion 43 while sufficiently increasing the number of overlapping layers of the base portion 43 in order to ensure sufficient welding strength.

[0337] The bending of the segment piece 61 is performed at line G passing through the bottom of the cutting groove 63 or above it. The cutting groove 63 enables smooth and easy bending of the segment piece 61 in the radial direction of the electrode assembly.

[0338] The width D of the segment piece 61 is defined as the length between two points where two straight lines extending from the side edges 63b on both sides of the segment piece 61 intersect with a straight line extending from the bottom 63a of the cutting groove 63. The height H of the segment piece 61 is defined as the shortest distance between the uppermost edge of the segment piece 61 and the straight line extending from the bottom 63a of the cutting groove 63. The separation pitch P of the segment piece 61 is defined as the length between two points where the straight line extending from the bottom 63a of the cutting groove 63 intersects with the straight lines extending from the two side edges 63b connected to the bottom 63a. When the side edge 63b and / or the bottom 63a is a curve, the straight line may be replaced by a tangent line extending from the intersection of the side edge 63b and the bottom 63a to the side edge 63b and / or the bottom 63a.

[0339] Preferably, the width D of the segment piece 61 is 1 mm or more. If D is less than 1 mm, when the segment piece 61 is bent toward the core side, the segment pieces 61 may not overlap to an extent that can sufficiently ensure the welding strength, or there may be a risk of generating an empty space (gap).

[0340] Preferably, the width D of the slit piece 61 can be adaptively adjusted according to the radius of the winding turn in which the slit piece 61 is located so that when the slit piece 61 is bent toward the core side of the electrode assembly, the slit piece 61 can easily overlap in the radial direction.

[0341] FIG. 14f is a view showing, with respect to the center O of the core of the electrode assembly, an arc A1A2 formed by the lower end (line segment D in FIG. 14e) of the slit piece 61 that defines the width D of the slit piece 61 when the electrode 60 is wound according to an embodiment of the present invention. ab ).

[0342] Referring to FIG. 14f, the arc A1A2 has a length corresponding to the width D of the slit piece 61 and has a central angle Φ with respect to the center of the core of the electrode assembly. The central angle Φ can be defined as the angle between two line segments connecting both ends of the arc A1A2 and the center O of the core on a plane perpendicular to the winding axis passing through the arc A1A2.

[0343] When the length of the arc A1A2 of the slit piece 61 is the same, the central angle Φ decreases as the radius r of the winding turn in which the slit piece 61 is located increases. Conversely, when the central angle Φ of the slit piece 61 is the same, the length of the arc A1A2 increases proportionally as the radius r of the winding turn in which the slit piece 61 is located increases.

[0344] The central 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.

[0345] The central angle Φ of the slit piece 61 can be 45° or less, preferably 30° or less, according to the radius r of the winding turn in which the slit piece 61 is located in order to improve the uniformity of bending and prevent the occurrence of cracks.

[0346] In one form, the central angle Φ of the segment 61 can gradually or stepwise increase or decrease along the radial direction of the electrode assembly within the above numerical range. In another form, the central angle Φ of the segment 61 can gradually or stepwise increase and then gradually or stepwise decrease along the radial direction of the electrode assembly within the above numerical range, and vice versa is also possible. In yet another form, the central angle Φ of the segment 61 can be substantially the same along the radial direction of the electrode assembly within the above numerical range.

[0347] According to experiments, when the central angle Φ of the segment 61 exceeds 45°, the bending pattern of the segment 61 becomes non-uniform. The difference in the forces applied to the central portion and the side portion of the segment 61 becomes large, and the pressing of the segment 61 in the circumferential direction becomes non-uniform. Also, if the pressing force is increased for the sake of bending uniformity, there is a risk of cracks occurring in the plain portion 43 near the cutting groove 63.

[0348] In one example, the central 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%.

[0349] 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 point with a radius of 7 mm, when the central 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.

[0350]

Table 1

[0351] 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.

[0352] [Equation 1] 1 ≦ D(r) ≦ (2 × π × r / 360°) × 45°

[0353] 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 reference to the center of the core of the electrode assembly, the width D(r) in the winding direction may gradually or stepwise increase, or vice versa.

[0354] In other forms, 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 reference to the center of the core of the electrode assembly, the width D(r) in the winding direction may gradually or stepwise increase within the range of 1 mm to 11 mm, or vice versa.

[0355] In still other forms, 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 reference to the center of the core of the electrode assembly, the width D(r) in the winding direction may gradually or stepwise increase and then gradually or stepwise decrease, or vice versa.

[0356] In still other forms, 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 reference to the center of the core of the electrode assembly, the width D(r) in the winding direction may gradually or stepwise increase within the range of 1 mm to 11 mm and then gradually or stepwise decrease, or vice versa.

[0357] In still other forms, as the radius r of the winding turn in which the segment 61 is located increases, the ratio of the change in the width D(r) of the segment 61 may be the same or different.

[0358] In still other forms, as the radius r of the winding turn in which the segment 61 is located increases, the ratio at which the width D(r) of the segment 61 changes within the range of 1 mm to 11 mm may be the same or different.

[0359] Referring further to FIG. 14e, 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 a sufficient extent to ensure sufficient welding strength, or that an empty space (gap) will be generated.

[0360] 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.

[0361] 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.

[0362] In one example, when the height H of the segment 61 gradually increases in N steps from h1 to h as the radius of the winding turn increases N up to, the k-th height h k (k is a natural number from 1 to N), 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 , the heights h1 to h of the segment 61 can be determined so that the following formula 2 is satisfied. N

[0363] [Formula 2] 2 mm ≤ h k ≤ r k - α × r c (preferably, α is 0.90 to 1)

[0364] The height h of the segment 61 kWhen the following formula (2) is satisfied, 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.

[0365] 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 sequence as 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.

[0366] In this case, the radius r of the core of the electrode assembly c The starting radii r1, r2, r3, r3 of the winding turns including the segmented piece 61 having heights of 3 mm, 4 mm, 5 mm, and 6 mm according to r are as shown in Table 2 below when α is 1 and the equal sign condition is applied in the right inequality.

[0367]

Table 2

[0368] When the segmented piece 61 is arranged 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, r1, r2, r3, r3 shown in Table 2 can be shifted toward the core side according to the α value. In one example, when α is 0.90, r1, r2, r3, r3 can be shifted toward the core side by 10% of the core radius. In this case, when the segmented piece 61 is bent toward the core side, 10% of the core radius is blocked by the segmented piece 61. r1, r2, r3, r3 shown in Table 2 are the limit values of the position where the segmented piece 61 starts. Therefore, the position of the segmented piece 61 can be shifted by a predetermined distance to the outer peripheral side from the radius shown in Table 2.

[0369] FIG. 14g shows the heights h1, h2, h3, h4 of the segmented piece 61 and the core radius r cIt is a diagram schematically showing the relationship between the radii r1, r2, r3, r3 of the winding turns at which the segment 61 starts to appear.

[0370] Referring to Table 2 and FIG. 14g, for example, when the radius r of the core C c is 3 m, the starting radii r1, r2, r3, and r3 of the winding turns including the segment 61 having heights of 3 mm (h1), 4 mm (h2), 5 mm (h3), and 6 mm (h4) can be 6 mm, 7 mm, 8 mm, and 9 mm respectively, and the height of the segment 61 can be maintained at 6 mm from a radius of 9 mm to the last winding turn. Also, the winding turns having a radius smaller than 6 mm (r1) may not include the segment 61. In such an example, since the segment 61 with a height of 3 mm (h1) closest to the core C is located from the winding turn with a radius of 6 mm, even if the corresponding segment 61 is bent toward the core C side, it only covers the radius range of 3 mm to 6 mm and does not substantially block the core C. Depending on the α value in Equation 2, the position of the segment 61 can be shifted toward the core C side within 10% of the core radius r c and can be shifted within 10% of the core radius r toward the core C side.

[0371] In other forms, the height of the segment 61 can increase at the same or different ratios as the starting radius r of the winding turn where the segment 61 is located increases with reference to the center of the core of the electrode assembly.

[0372] Preferably, the height H of the segment 61 satisfies Equation 2 and the maximum height of the segment 61 can be limited.

[0373] FIG. 14h is a conceptual diagram for determining the maximum value h max with respect to the height H of the segment 61 in the variable height range of the segment 61.

[0374] Referring to FIG. 14h, in the winding structure of the electrode assembly, the electrode E1 including the segment 61 faces the electrode E2 of the opposite polarity with the separation membrane S interposed in the radial direction. The active material layer E 1,active is coated on both sides of the electrode E1, and the active material layer E 2,active is also coated on both sides of the electrode E2. For electrical insulation, the end S of the separation membrane Send is the end E of the electrode E2 2,end and can further extend outward by a length corresponding to the insulation gap W gap . Also, the end of the electrode E1 does not extend outward beyond the end of the electrode E2 for electrical insulation. Therefore, a section corresponding to the insulation gap W gap must be ensured at the lower end of the plain portion 43. Also, when the electrodes E1, E2 and the separation film S are wound, the end S end of the separation film S meanders. Therefore, in order for the segment 61 to be exposed outside the separation film S, a section W margin,min corresponding to the minimum meandering margin of the separation film S must be assigned to the plain portion 43. Also, in order to cut the segment 61, a minimum cutting scrap margin W scrap,min must be assigned to the end of the current collector foil. Therefore, the maximum height h max of the segment 61 in the height variable section of the segment 61 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.

[0375] [Equation 3] h max = W foil - W scrap,min - W margin,min - W gap

[0376] Preferably, the insulation gap W gap can be 0.2 mm to 6 mm when the first electrode is the positive electrode. Also, the insulation gap W gap can be 0.1 mm to 2 mm when the first electrode is the negative electrode.

[0377] Preferably, the minimum cutting scrap margin W scrap,min can be 1.5 mm to 8 mm. The minimum cutting scrap margin W scrap,minmay not be assigned depending on the process of forming the segmented piece 61. For example, a cutting groove 63 may be formed such that the upper side of the segmented piece 61 coincides with the upper side of the current collector foil. In this case, in Equation 3, W scrap,min can be 0.

[0378] Preferably, the minimum meandering margin W of the separation membrane margin,min can be 0 to 1 mm.

[0379] As an example, the minimum cutting scrap margin W scrap,min is 1.5 mm, and the minimum meandering margin W of the separation membrane S margin,min can be 0.5 mm. Under such conditions, the width W of the current collector foil before forming the segmented piece 61 foil is 8 mm to 12 mm, and when 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 segmented piece 61 using Equation 3 max are as shown in Table 3 below.

[0380]

Table 3

[0381] Referring to Table 3, the maximum height h of the segmented piece 61 in the height variable range of the segmented piece 61 max can be set to 10 mm. Therefore, the height of the segmented piece 61 in the height variable range of the segmented piece 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.

[0382] Referring further to FIG. 14e, the separation pitch P of the segmented piece 61 can be adjusted in the range of 0.05 to 1.0 mm. If the separation pitch P is less than 0.05 mm, when the electrode 60 travels during the winding process or the like, there is a risk of cracks occurring in the non-patterned portion 43 near the bottom of the cutting groove 63 due to stress. On the other hand, if the separation pitch P exceeds 1 mm, when the segmented piece 61 is bent, there is a risk that the segmented piece 61 may not overlap to ensure sufficient welding strength, or a void (gap) may occur.

[0383] 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 if 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.

[0384] 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, no crack occurs at the lower part of the cutting groove 63 when the electrode 60 travels under the above running conditions.

[0385] As shown in FIG. 14e, a cutting groove 63 is interposed between two adjacent segment pieces 61 in the winding direction (X axis). The cutting groove 63 corresponds to a space generated while the plain part 43 is removed. Preferably, the corner portions at both ends of the bottom of the cutting groove 63 are round. That is, the cutting groove 63 includes a substantially flat bottom 63a and a round portion 63c. The round portion 63c connects the bottom 63a and the side 63b of the segment piece 61. In a modified example, the bottom 63a of the cutting groove 63 can be replaced with an arc shape. In this case, the sides 63b of the segment piece 61 can be smoothly connected by the arc shape of the bottom 63a.

[0386] The radius of curvature of the round portion 63c can be more than 0 and 0.5 mm or less, preferably more than 0 and 0.1 mm or less, and more preferably 0.01 mm to 0.05 m. When the radius of curvature of the round portion 63c satisfies the above numerical range, it is possible to prevent cracks from occurring at the lower part of the cutting groove 63 when the electrode 60 travels during a winding process or the like.

[0387] The plurality of segment pieces 61 may have an increasing lower inner angle θ from the core side toward the outer peripheral side. As an example, the plurality of segment pieces 61 may have a gradually or stepwise increasing lower inner angle θ from the core side toward the outer peripheral side. The lower inner angle θ is an angle between a straight line extending from the bottom 63a of the cutting groove 63 and a straight line extending from the side portion 53b of the segment piece 61. When the segment piece 61 is bilaterally symmetric, the lower inner angles θ on the left and right sides are substantially the same.

[0388] 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 with the increase in the radius of the electrode assembly, when the segment piece 61 is bent, the stress generated in the radial direction and the circumferential direction can be relaxed. Also, 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.

[0389] Preferably, the lower inner angle θ can be determined by the radius of the winding turn where the segment piece 61 is located and the width D of the segment piece 61.

[0390] FIG. 14i is a schematic diagram for explaining a mathematical formula for determining the lower inner angle θ of the segment piece 61.

[0391] Referring to FIG. 14i, 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 and A and D which are the two ends of the line segment AD corresponding to the width D of the segment piece 61.

[0392] 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 where 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.

[0393]

Equation

[0394] The angle of Equation 4 is the lower inner angle θ of the segment 61 refer which is the ideal reference angle. 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 a maximum of p / 2 up 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' in which the tolerance due to the separation pitch P is reflected. In Equation 5, H is the height of the segment 61, and p corresponds to the separation pitch.

[0395]

Number

[0396] 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.

[0397]

Number

[0398] 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.

[0399] 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.

[0400] 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, it can still be designed such that the lower inner corner θ on at least one side satisfies the above-mentioned formula 6.

[0401] Referring further to FIG. 14d, 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 towards 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.

[0402] The bending point of the split piece 61 can be set at a line passing through the bottom of the cutting groove 63 or a point separated from that line by a predetermined distance upward. If the split piece 61 is bent towards the core side at a point separated from the bottom of the cutting groove 63 by a predetermined distance, the overlap 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 respect to the center of the core. At this time, if the bending point is separated from the bottom of the cutting groove 63 by a predetermined distance, the overlap 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.

[0403] In one example, the width of each split piece group can be designed to form 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.

[0404] In other modifications, the width of each slit piece group can be designed to constitute at least one winding turn of the electrode assembly.

[0405] 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.

[0406] Groups 1 to 8 are merely an example of the slit piece groups included in the third part 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 multiply to maximize the dispersion of stress during the bending process of the non-textured portion 43 and sufficiently ensure the welding strength with the current collector.

[0407] In other modifications, the height of the second part B3 can decrease gradually or stepwise as in the first and second embodiments.

[0408] In yet another modification, the slitting structure of the third part B2 can be extended up to the second part B3 (see the dotted line). In this case, the second part B3 can also include a plurality of slit pieces, similar to the third part B2. Preferably, the slitting structure of the second part B3 can be substantially the same as the outermost slit piece group of the third part B2. In this case, the slit pieces included in the second part B3 and the third part B2 can have substantially the same width, height, and separation pitch. As a modification, the slit pieces of the second part B3 can have a width and / or height and / or separation pitch larger than that of the third part B2.

[0409] In the third part B2, with reference to the winding direction of the electrode 60, the section where the height of the slit piece 61 increases stepwise (Groups 1 to 7) can be defined as the height variable section of the slit piece, and the last slit piece group (Group 8) can be defined as the height uniform section where the height of the slit piece is maintained uniformly.

[0410] That is, in the third part B2, where the height of the slit piece 61 changes from h1 to hN when increasing step by step up to, h1~h N-1 (N is a high index and a natural number of 2 or more), the section where the segment 61 with a height of is arranged corresponds to a height variable section, and h N The section where the segment 61 with a height of 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 embodiments.

[0411] When the electrode 60 is used to manufacture the electrode assembly of the cylindrical battery with a form factor 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, similar to the width of the first part B1.

[0412] The reason why the widths of groups 1 to 8 do not show a constant increase or decrease pattern is that the width of the segment gradually increases from group 1 to group 8, but the number of segments included in the 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.

[0413] That is, in the circumferential direction of the electrode assembly, when the winding widths for each of three continuously adjacent partial segment groups are W1, W2, and W3, respectively, it may include a combination of partial segment groups in which W3 / W2 is smaller than W2 / W1.

[0414] In the specific example described above, 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%.

[0415] According to still another modification, when the plain portion 43 of the electrode 60 has a partial segment structure, the electrode 60 may include a partial segment omission section 64 in which some of the plurality of partial segments are regularly or irregularly omitted, as shown in FIG. 14j.

[0416] Preferably, there may be a plurality of partial segment omission sections 64. As an example, the width of the partial segment omission section 64 may be constant from the core side toward the outer peripheral side. As another example, the width of the partial 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 present in the partial segment omission section 64 may correspond to the height of the first portion B1 and / or the second portion B3.

[0417] The number of partial segments 61 present between the partial segment omission sections 64 may be at least one. As shown in FIG. 14j, the electrode 60 may include a plain portion section in which the number of partial segments 61 present between the partial segment omission sections 64 increases from the core toward the outer peripheral side.

[0418] Preferably, as shown in FIG. 14k, the width of the partial segment omission section 64 may be set such that when the electrode 60 is wound, the partial segments located in each winding turn are located within a preset independent region 66 with respect to the center C of the core of the electrode assembly 65.

[0419] That is, when the plurality of segment pieces 61 are viewed in the winding axis direction of the electrode assembly 65, they can be located within a plurality of independent regions 66 with respect to the center C of the core. The number of independent regions 66 can vary to two, three, four, five, etc.

[0420] Preferably, the independent region 66 can be in a fan shape. In this case, the angles between the independent regions 66 can be substantially the same. Also, the central angle δ of the independent region 66 can be 20° or more, selectively 25° or more, selectively 30° or more, selectively 35° or more, or selectively 40° or more.

[0421] In a modified example, the independent region 66 can have the form of a geometric figure such as a square, rectangle, parallelogram, trapezoid, etc.

[0422] In one embodiment of the present invention, the shape of the segment piece 61 can be variously deformed.

[0423] FIG. 15a is a plan view showing the structure of the electrode 70 according to the fifth embodiment of the present invention.

[0424] Referring to FIG. 15a, the electrode 70 of the fifth embodiment has substantially the same other configuration except that the shape of the segment piece 61' is different from that of the above-described embodiment. Therefore, unless otherwise specified, the configuration of the fourth embodiment can be similarly applied to the fifth embodiment.

[0425] The segment piece 61' has the form of a geometric figure in which the upper width and the lower width are substantially the same. Preferably, the segment piece 61' can be square-shaped.

[0426] FIG. 15b is a view showing the definition of the width, height, and separation pitch of the square segment piece 61'.

[0427] Referring to FIG. 15b, the width D, height H, and separation pitch P of the segmented piece 61' are set such that when the plain portion 43 is bent, the number of overlapping layers of the plain portion 43 is sufficiently increased to prevent the plain portion 43 from tearing and to improve the welding strength with the current collector, and abnormal deformation of the plain portion 43 can be prevented. Abnormal deformation means that the plain portion below the bending point cannot maintain a straight state and collapses and is irregularly deformed.

[0428] The width D of the segmented piece 61' is defined as the length between two points where two straight lines extending from the side edges on both sides of the segmented piece 61' intersect with a straight line extending from the bottom 63a of the cutting groove 63. The height H of the segmented piece 61' is defined as the shortest distance between the uppermost edge of the segmented piece 61' and a straight line extending from the bottom 63a of the cutting groove 63. The separation pitch P of the segmented piece 61' is defined as the length between two points where a straight line extending from the bottom 63a of the cutting groove 63 intersects with straight lines extending from two side edges 63b connected to the bottom 63a. When the side edge 63b and / or the bottom 63a is a curve, the straight line can be replaced by a tangent line extending from the intersection of the side edge 63b and the bottom 63a to the side edge 63b and / or the bottom 63a.

[0429] Preferably, the conditions regarding the width D, height H, and separation pitch P of the segmented piece 61' are substantially the same as those of the fourth embodiment described above, so repeated explanations are omitted. However, since the segmented piece 61' is square, the lower inner angle of the segmented piece 61' can be constant at 90°.

[0430] Similar to the electrode 60 of the fourth embodiment, the electrode 70 according to the fifth embodiment may also include a segmented piece omission section 64 in which some of the plurality of segmented pieces are regularly or irregularly omitted, as shown in FIG. 15c.

[0431] Also, when the electrode 70 including the segmented piece omission section 64 is wound as an electrode assembly, the segmented pieces can be located within a plurality of independent regions 66 as shown in FIG. 14k.

[0432] When the third part B2 and the second part B3 include a plurality of sub-sections 61, 61' as in the fourth and fifth embodiments, the shapes of the respective sub-sections 61, 61' can be variously deformed.

[0433] Preferably, the sub-sections can be deformed in various forms while satisfying at least one of the following conditions.

[0434] Condition 1: The width of the lower part is wider than the width of the upper part.

[0435] Condition 2: The width of the lower part is equal to the width of the upper part.

[0436] Condition 3: The width is maintained the same from the lower part to the upper part.

[0437] Condition 4: The width decreases from the lower part to the upper part.

[0438] Condition 5: The width decreases from the lower part to the upper part and then increases.

[0439] Condition 6: The width increases from the lower part to the upper part and then decreases.

[0440] Condition 7: The width increases from the lower part to the upper part and then is maintained constant.

[0441] Condition 8: The width decreases from the lower part to the upper part and then is maintained constant.

[0442] Condition 9: One inner angle on the lower side and the other inner angle on the lower side of the sub-section are the same.

[0443] Here, the inner angle can be defined as the angle formed by the side of the sub-section with respect to the width direction of the lower part of the sub-section. When the side is a curve, the inner angle is defined as the angle between the tangent line drawn at the lowest point of the curve and the width direction of the lower part of the sub-section.

[0444] Condition 10: One inner angle on the lower side and the other inner angle on the lower side of the sub-section are different.

[0445] Condition 11: The lower inner angle on one side and the lower inner angle on the other side each have an acute angle, a right angle, or an obtuse angle.

[0446] Condition 12: It is symmetric about the winding axis direction.

[0447] Condition 13: It is asymmetric about the winding axis direction.

[0448] Condition 14: The side is linear.

[0449] Condition 15: The side is curved.

[0450] Condition 16: The side is convex outward.

[0451] Condition 17: The side is convex inward.

[0452] Condition 18: The upper and / or lower corners have a structure where a straight line intersects with a straight line.

[0453] Condition 19: The upper and / or lower corners have a structure where a straight line intersects with a curve.

[0454] Condition 20: The upper and / or lower corners have a structure where a curve intersects with a curve.

[0455] Condition 21: The upper and / or lower corners have a round structure.

[0456] Figure 16 is a diagram exemplarily showing the form of a segmented slice according to a modified form of the present invention.

[0457] As shown in the illustration, the segmented slice can have the 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 of these is connected. As an example, the segmented slice can have a polygonal shape, a round pattern, or various forms in which these are combined.

[0458] Specifically, the segmented slice can be in the shape of a bilaterally symmetric trapezoid (round a); a bilaterally asymmetric trapezoid (round b); a parallelogram (round c); a triangle (round l); a pentagon (round k); an arc shape (round e); or an ellipse shape (round f).

[0459] The shape of the segmented slice is not limited to that shown in Fig. 16, and can 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.

[0460] In the polygonal shapes of the segmented slice, namely round a, round b, round c, round k, and round l, the upper corners and / or the lower corners can be in a shape where straight lines intersect or in a round shape (see the enlargement of the upper corners and lower corners of round a).

[0461] In the polygonal shapes of the segmented slice, namely round a, round b, round c, round k, and round l, and the round shapes of the segmented slice, namely round e and round f, the lower one-side interior angle θ1 and the other-side interior angle θ2 can be the same or different, and the lower one-side interior angle θ1 and the other-side interior angle θ2 can be an acute angle, a right angle, or an obtuse angle respectively. The interior angle is the angle formed by the base and the 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 point of the base and the side.

[0462] The shape of the side of the polygonal segmented slice can be deformed in various ways.

[0463] As an example, the side of the segmented slice in the shape of round a can be deformed into a curve bulging outward like the shape of round d, or into a curve concave inward inside the segmented slice like the shape of round g or round j.

[0464] As another example, the side of the segmented slice in the shape of round a can be deformed into a broken line concave inward inside the segmented slice like the shape of round h or round i. Although not shown, the side of the segmented slice in the shape of round a can be deformed into a broken line bulging outward.

[0465] In the forms of the segment pieces with variously deformed sides, namely round d, round g, round j, round h, and round i, the lower one-side inner angle θ1 and the other-side inner angle θ2 may be the same or different, and the lower one-side inner angle θ1 and the other-side inner angle θ2 can each be an acute angle, a right angle, or an obtuse angle.

[0466] The width of the segment piece can have various change patterns from the lower part to the upper part.

[0467] As an example, the width of the segment piece can be maintained constant from the lower part to the upper part (round form c). As another example, the width of the segment piece can gradually decrease from the lower part to the upper part (round forms a, b, d, e, f, and g). As still another example, the width of the segment piece 61 can decrease gradually from the lower part to the upper part and then increase (round forms i and j). As still another example, the width of the segment piece can increase gradually from the lower part to the upper part and then decrease (round form k). As still another example, the width of the segment piece can decrease gradually from the lower part to the upper part and then be maintained constant (round form h). Although not shown, the width of the segment piece can increase gradually from the lower part to the upper part and then be maintained constant.

[0468] On the other hand, among the forms of the segment pieces illustrated in FIG. 16, the upper flat polygonal shape can be rotated 180°. As an example, when the round form a, b, d, or g of the segment piece 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 round form h of the segment piece 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.

[0469] In the above-described embodiments (deformed forms), 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 (e.g., semi-circular, elliptical, etc.) advantageous for stress dispersion can be applied to the section where stress is concentrated, and a polygonal shape (e.g., quadrilateral, trapezoid, parallelogram, etc.) with the largest area can be applied to the section where stress is relatively low.

[0470] In still other forms, the plurality of slit pieces may 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.

[0471] In the above-described embodiments (modification forms), 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 slit pieces 61, 61' of the third part B2 are bent, there is a possibility that a reverse forming phenomenon occurs in which the end portion 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 slit pieces 61, 61' to a level at which reverse forming does not occur.

[0472] Also, according to still another aspect of the present invention, after the electrodes 60, 70 are wound as an electrode assembly, the slit 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.

[0473] FIG. 17a is a schematic diagram showing a cross section of a bent surface region F formed while the slit piece 61 is bent toward the core C side of the electrode assembly 80. In FIG. 17a, 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. 17b is a perspective view schematically showing the electrode assembly 80 in which the bent surface region F is formed.

[0474] Referring to FIGS. 17a and 17b, the bent surface region F has a structure in which the segmented pieces 61 overlap in a plurality of layers in the winding axis direction. The overlapping direction is the winding axis direction (Y-axis). The circular section 1 is a segmented piece omission section (first part B1) without segmented pieces, and the circular sections 2 and 3 are sections where the winding turns including segmented pieces are located. The circular section 2 is a height variable section where the height of the segmented piece 61 changes, and the circular section 3 is a height uniform section where the height of the segmented piece is maintained uniformly up to the outer circumference of the electrode assembly. As will be described later, the radial lengths of the circular sections 2 and 3 can vary. On the other hand, at least one winding turn including the outermost winding turn may not include a segmented structure in the plain part (second part B3). In this case, the second part B3 can be excluded from the circular section 3.

[0475] In the circular section 2, the height of the segmented piece 61 is from the minimum height h1 (=h N ) to the maximum height h min (=h N (=h max ) and can change stepwise in the section of r1~r N . The height variable section where the height of the segmented piece 61 changes is r1~r N . From the radius r N to the radius R of the electrode assembly 80, the height of the segmented piece 61 is maintained uniformly at h N . That the height is uniform means that the height deviation is within 5%.

[0476] At any radial position of the circular sections 2 and 3, the number of stacked layers of the segmented piece 61 varies depending on the radial position. Also, the number of stacked layers of the segmented piece 61 can vary depending on the width of the circular section 2, the minimum height h1 and the maximum height h N of the segmented piece in the height variable section of the segmented piece 61, and the height change amount Δh of the segmented piece 61. The number of stacked layers of the segmented piece 61 is the number of segmented pieces intersecting the virtual line when a virtual line is drawn in the winding axis direction from any radial position of the electrode assembly 80.

[0477] Preferably, by adjusting the height, width and separation pitch of the segmented piece 61 according to the radius of the winding turn including the segmented piece 61, the number of stacked layers of the segmented piece 61 at each position of the bent surface region F can be optimized according to the required welding strength of the current collector.

[0478] First, when the minimum height h1 of the segment 61 is the same in the height variable range (circle 2) of the segment 61, how the number of layers of the segment 61 changes along the radial direction of the bent surface region F as the maximum height h N of the segment 61 changes will be described with specific examples.

[0479] 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 electrode and the negative electrode included in the electrode assembly have the electrode structure shown in FIG. 14d. That is, the form of the segment is trapezoidal. The second portions B3 of the positive electrode and the negative electrode do not include segments. The length of the second portion B3 is 3% to 4% of the total length of the electrode. The positive electrode, the negative electrode, and the separator were wound by the method described with reference to FIG. 2. The winding turns are between 48 turns and 56 turns, but the winding turns of the example are 51 turns. The thicknesses of the positive electrode, the negative electrode, and the separator are 149 μm, 193 μm, and 13 μm, respectively. The thicknesses of the positive electrode and the negative electrode are the thicknesses including the thickness of the active material layer. The thicknesses of the positive electrode current collector and the negative electrode current collector are 15 μm and 10 μm, respectively. The lengths of the positive electrode and the negative electrode in the winding direction are 3948 mm and 4045 mm, respectively.

[0480] In each example, the minimum height of the segment 61 was set to 3 mm so that the height variable range (circle 2) of the segment 61 starts from a radius of 5 mm. Also, in each example, the height of the segment 61 was increased by 1 mm each time the radius increased by 1 mm, and the maximum height of the segment 61 was varied from 4 mm to 10 mm.

[0481] 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.

[0482] FIG. 17c 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. 17d and 17e described later.

[0483] Referring to Fig. 17c, the number-average lamination interval b1 of the segmented slices commonly appears in Examples 1-1 to 1-7 and Comparative Example 1. The number-average lamination interval b1 is the radius interval of the flat region in each graph. The length of the number-average lamination interval b1 increases as the maximum height of the segmented slice decreases, and the number-average lamination interval b1' of the comparative example is the longest. On the other hand, the number of laminations 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 number of laminations of the segmented slice increases while the width of the number-average lamination interval b1 decreases. Outside the number-average lamination interval b1, a lamination number decrease interval b2 appears where the number of laminations of the segmented slice decreases as the radius increases. The lamination number decrease interval b2 is a radius interval where the number of laminations of the segmented slice decreases as the radius of the electrode assembly increases. The number-average lamination interval b1 and the lamination number decrease 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 lamination number decrease interval b2, the amount of decrease in the number of laminations is proportional to the distance from the number-average lamination interval b1.

[0484] From the side of the number of laminations of the segmented slice, in Examples 1-1 to 1-7, the number of laminations of the segmented slice in the number-average lamination interval b1 of the segmented slice is 10 or more. The region where the number of laminations of the segmented slice is 10 or more can be set as a preferable welding target region. The welding target region is a section where at least a part of the current collector is welded.

[0485] In Examples 1-1 to 1-7, the number-average lamination 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.

[0486] 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. 17a) 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 (i) of the electrode region corresponding to the height-uniform section to the total length of the electrode, etc.

[0487] 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-decorated 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 obtained by rounding off the first decimal place. These are substantially the same in Tables 5 and 6 described later.

[0488]

Table 4

[0489] Referring to Examples 1-1 to 1-7 in Table 4, the number of stacked segmented slices is 11 to 26, 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 stacked 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. 17a) 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 (the 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%.

[0490] The number of stacked slices (g) in the stacked number uniform interval is 10 or more for all of Examples 1-1 to 1-7. The stacked number uniform interval (e) decreases as the height variable interval (d) of the segmented slices increases, but the number of stacked segmented slices (g) increases in the stacked number uniform interval (e). Preferably, the stacked number uniform interval (e) in which the number of stacked segmented slices (g) is 10 or more can be set as the welding target region.

[0491] Cylindrical batteries having form factors of 1865 and 2170 have a radius of the electrode assembly of approximately 9 mm to 10 mm. Therefore, for conventional cylindrical batteries, as in Examples 1-1 to 1-7, the radial length of the slitting section (f) cannot be ensured at the 17 mm level, and the length of the uniformly laminated section (e) with 10 or more lamination numbers of the slit pieces 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 radial section where the slit pieces 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.

[0492] Next, when the maximum height h of the slit pieces is the same in the height variable section of the slit pieces (circle 2 in Fig. 17a), how the number of laminations of the slit pieces changes along the radial direction of the bent surface area F will be described with specific examples based on the change in the minimum height h1 of the slit pieces. N When the maximum height h of the slit pieces is the same, how the number of laminations of the slit pieces changes along the radial direction of the bent surface area F will be described with specific examples based on the change in the minimum height h1 of the slit pieces.

[0493] 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 h1 in the height variable section of the slit pieces 61 (circle 2 in Fig. 17a) is the same as 4 mm, and the maximum height h N was changed in 1 mm units from 6 mm to 10 mm. Therefore, the electrode assemblies of Examples 2-1 to 2-5 have widths of 2 mm, 3 mm, 4 mm, 5 mm, and 6 mm respectively in the height variable section of the slit pieces (circle 2 in Fig. 17a), and the slit piece omission section (circle 1 in Fig. 17a) is a radial section from a radius of 2 mm to 6 mm.

[0494] 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 h1 in the height variable section (circle 2 in Fig. 17a) of the segmented slice 61 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 2 mm, 3 mm, 4 mm, and 5 mm respectively in the height variable section (circle 2 in Fig. 17a) of the segmented slice, and the segmented slice omission section (circle 1 in Fig. 17a) is a radial section from a radius of 2 mm to 7 mm.

[0495] 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 h1 in the height variable section (circle 2 in Fig. 17a) of the segmented slice 61 is the same as 6 mm, and the maximum height h N was changed in 1 mm increments from 8 mm to 10 mm. Therefore, the electrode assemblies of Examples 4-1 to 4-3 have widths of 2 mm, 3 mm, and 4 mm respectively in the height variable section (circle 2 in Fig. 17a) of the segmented slice, and the segmented slice omission section (circle 1 in Fig. 17a) is a radial section from a radius of 2 mm to 8 mm.

[0496] 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 h1 in the height variable section (circle 2 in Fig. 17a) of the segmented slice 61 is the same as 7 mm, and the maximum height h N was changed in 1 mm increments from 9 mm to 10 mm. Therefore, the electrode assemblies of Examples 5-1 to 5-2 have widths of 2 mm and 3 mm respectively in the height variable section (circle 2 in Fig. 17a) of the segmented slice, and the segmented slice omission section (circle 1 in Fig. 17a) is a radial section from a radius of 2 mm to 9 mm.

[0497] Fig. 17d 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 results are shown in the bent surface region of the negative electrode.

[0498] In Fig. 17d, graph (a) shows the result of counting the number of stacked segments along the radial direction in the bent surface region F for Examples 2-1 to 2-5, graph (b) shows the result for Examples 3-1 to 3-4, graph (c) shows the result for Examples 4-1 to 4-3, and graph (d) shows the result for Examples 5-1 and 5-2.

[0499] Referring to Fig. 17d, the average stacking number section b1 of the segments commonly appears in all examples. The average stacking number section b1 is the radial section of the flat region in the graph. When the minimum height h1 of the segments is the same, the length of the average stacking number section b1 increases as the maximum height h N of the segments decreases. Also, when the maximum height h N of the segments is the same, the length of the average stacking number section b1 increases as the minimum height h1 of the segments decreases. On the other hand, in the average stacking number section b1, the number of stacked segments increases as the maximum height h N of the segments increases. In the examples, a stacking number decreasing section b2 also appears adjacent to the average stacking number section b1.

[0500] In the examples, the number of stacked segments of the segments in the average stacking number section b1 is all 10 or more. Preferably, the region where the number of stacked segments of the segments is 10 or more can be set as a preferable welding target region.

[0501] In the examples, the average stacking number section b1 starts from the radial point where the height variable section (circle 2 in Fig. 17a) of the segments begins. In Examples 2-1 to 2-5, the height variable section (circle 2 in Fig. 17a) of the segments starts from 6 mm and extends to the outer peripheral side. In Examples 3-1 to 3-4, the height variable section (circle 2 in Fig. 17a) of the segments starts from 7 mm and extends to the outer peripheral side. In Examples 4-3 to 4-3, the height variable section (circle 2 in Fig. 17a) of the segments starts from 8 mm and extends to the outer peripheral side. In Examples 5-1 and 5-2, the height variable section (circle 2 in Fig. 17a) of the segments starts from 9 mm and extends to the outer peripheral side.

[0502] Table 5 below shows the results of calculating various parameters including the ratio (e / f) of the length of the stacked number average section to the length from the radius points (6 mm, 7 mm, 8 mm, 9 mm) where the stacked number average section starts to the outermost point (22 mm) of the electrode assembly, and the ratio (d / f) of the length of the height variable section (circle 2) of the segmented slice to the length from the radius points (6 mm, 7 mm, 8 mm, 9 mm) where the stacked number average section starts to the outermost point (22 mm) 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.

[0503]

Table 5

[0504] Referring to Examples 2-5, 3-4, 4-3 and 5-2 in Table 5 together with FIGS. 17a and 17d, 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 h1 of the segmented slice increases by 1 mm each to 4 mm, 5 mm, 6 mm, 7 mm, and the length of the height variable section (circle 2) decreases by 1 mm each to 6 mm, 5 mm, 4 mm, 3 mm. In the four examples, the ratio (e / f) of the stacked number average section is the largest at 69% for Example 2-5 and the smallest at 38% for Example 5-2, and the number of stacks in the stacked number average section is all equal.

[0505] 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 h1 of the segmented slice decreases and the width of the height variable section (circle 2) of the segmented slice increases, the width of the stacked number average section also proportionally increases. The reason is that the smaller the minimum length h1 of the segmented slice, the closer the radius point where the segmented slice starts is to the core side, and the area where the segmented slice is stacked is extended to the core side.

[0506] Referring to Table 5, it can be seen that the number of laminations of the segmented slices is 16 to 26, the ratio (d / f) of the variable-height interval (circle 2) of the segmented slices is 13% to 38%, and the ratio (e / f) of the uniform-lamination-number interval is 31% to 69%. Also, the ratio (c / (b - a)) of the segmented-slice omission interval (circle 1) to the radius (b - a) of the electrode assembly excluding the core is 20% to 35%. Further, the ratio of the length of the electrode region corresponding to the segmented-slice omission interval (circle 1) to the overall length of the electrode is 10% to 20%, the ratio of the length of the electrode region corresponding to the variable-height interval (circle 2) to the overall length of the electrode is 6% to 25%, and the ratio of the length of the electrode region corresponding to the uniform-height interval (circle 3) to the overall length of the electrode is 62% to 81%.

[0507] Cylindrical batteries having form factors of 1865 and 2170 have a radius of the electrode assembly of about 9 mm to 10 mm. Therefore, as in the embodiment, it is not possible to ensure that the radial length of the segmented-slice interval (f) is at a level of 13 mm to 16 mm, and while ensuring that the length of the segmented-slice omission interval (c, circle 1) is about 4 mm to 7 mm, it is not possible to ensure that the length of the uniform-lamination-number interval (e) where the number of laminations of the segmented slices is 10 or more is at a level of 5 mm to 11 mm. This is because in a conventional cylindrical battery, when the radius of the core is designed to be 2 mm, the same as in the embodiment, the radial interval where 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 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 (the positive electrode is 3948 mm and the negative electrode is 4045 mm). Therefore, the numerical ranges for parameters h, i, and j cannot be easily derived from the design specifications of conventional cylindrical batteries either.

[0508] Next, when the minimum height h1 and the maximum height h of the segmented slices are the same in the variable-height interval (circle 2) of the segmented slices, specific examples will be given to explain how the number of laminations of the segmented slices changes along the radial direction of the bending surface region F according to the diameter of the core C of the electrode assembly. N When they are the same, specific examples will be given to explain how the number of laminations of the segmented slices changes along the radial direction of the bending surface region F according to the diameter of the core C of the electrode assembly.

[0509] 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 h1 of the segment in the height variable section (circle 2) of the segment 61 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, the electrode assemblies of Examples 6-1 to 6-6 have widths of the height variable section (circle 2) of the segment of 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm, respectively, and the segment omission section (circle 1) is a radius section from a radius of 4 mm to 7 mm.

[0510] 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 h1 of the segment in the height variable section (circle 2) of the segment 61 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, the electrode assemblies of Examples 7-1 to 7-6 have widths of the height variable section (circle 2) of the segment of 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm, respectively, and the segment omission section (circle 1) is the same as a radius section from a radius of 2 mm to 5 mm.

[0511] FIG. 17e 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 result appears in the bent surface region of the negative electrode.

[0512] In FIG. 17e, 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.

[0513] Referring to FIG. 17e, a segment stacking number uniform section b1 commonly appears in all examples. The segment stacking number uniform section b1 is a radius section of a flat region in the graph. The length in the radial direction of the segment stacking number uniform section b1 is such that when the minimum height h1 of the segment is the same, the maximum height h of the segment Nincreases as it decreases. On the other hand, in the stacked-layer number uniform interval b1, the stacked-layer number of the segmented slice is the maximum height h of the segmented slice N increases as it increases. In the examples, a stacked-layer number decreasing interval b2 is confirmed adjacent to the stacked-layer number uniform interval b1.

[0514] In the examples, the stacked-layer number of the segmented slice in the stacked-layer number uniform interval b1 is all 10 or more. Preferably, the region where the stacked-layer number of the segmented slice is 10 or more can be set as a preferable welding target region.

[0515] In the examples, the stacked-layer number uniform interval b1 starts from the radius point where the height variable interval (circle 2) of the segmented slice starts. In the case of Examples 6-1 to 6-6, the radius where the height variable interval (circle 2) of the segmented slice starts is 7 mm, and in the case of Examples 7-1 to 7-6, the radius where the height variable interval (circle 2) of the segmented slice starts is 5 mm.

[0516] 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-layer number uniform interval to the length from the radius point (7 mm, 5 mm) where the stacked-layer number uniform interval starts to the outermost point (22 mm) of the electrode assembly, 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 (7 mm, 5 mm) where the stacked-layer number uniform interval starts to the outermost point (22 mm) of the electrode assembly, etc., are shown for the calculation results of various parameters.

[0517]

Table 6

[0518] Referring to FIG. 17a, and Examples 6-6 and 7-6 in Table 6, the minimum height h1 and the maximum height h of the segmented slice in the height variable interval (circle 2) of the segmented slice 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 number of laminations 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.

[0519] Referring to Table 6, it can be seen that the number of laminations of the cut section is 13 to 26, the ratio (d / f) of the height variable section (circle 2) of the cut section is 12% to 47%, and the ratio (e / f) of the length of the lamination number average section is 40% to 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% to 17%. Further, 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% to 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% to 83%.

[0520] 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 that the radial length of the slitting section (f) is at a level of 15 mm to 17 mm, and while ensuring that the length of the slitting section omission section (circle 1) is about 3 mm, it is not possible to ensure that the length of the layer number uniform section (e) where the number of layers of the slices is 10 or more is 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 radius section where the slitting 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 at a level of about 15% to 24% compared to 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 conventional cylindrical batteries.

[0521] Taking the data in Tables 4 to 6 into comprehensive consideration, the number of layers of the slitting sections in the layer number uniform section of the slitting sections can be 11 to 26. Also, the ratio (d / f) of the height variable section (circle 2) of the slitting 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 slitting section 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 slitting section 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 slitting 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 slitting sections to the total length of the electrode can be 59% to 87%.

[0522] 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 h1 and the maximum height h in the height variable section (circle 2) of the slitting sections 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.

[0523] 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 from 1% to 50%. Also, the ratio (e / f) of the number-average interval of layers can be extended from 30% to 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 from 10% to 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 from 1% to 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 from 1% to 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 from 50% to 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 of the height index N is 2 to 8. For example, referring to Table 4, the height indexes 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 to 20, and selectively, it can be further extended up to 2 to 30.

[0524] 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.

[0525] 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.

[0526] Preferably, other regions of the welding region of the current collector that do not overlap with the uniform lamination number region may overlap with the lamination number decreasing region adjacent to the uniform lamination number region in the radial direction.

[0527] 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 the region where the number of overlapping segments in the lamination number decreasing region is 10 or more.

[0528] Welding the current collector to the region where the number of laminated 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.

[0529] If the uniform lamination number region with 10 or more laminated segments 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 absorbs almost all of the laser energy to form weld beads, 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.

[0530] Also, since the number of laminated segments in the region irradiated with the laser is 10 or more, weld beads are formed with sufficient volume and thickness. Therefore, sufficient welding strength can be ensured, and the resistance at the welding interface can also be lowered to a level suitable for rapid charging.

[0531] 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 laminated segments. This is because as the number of laminated segments increases, the volume of the weld beads formed by the laser becomes larger. The weld beads are formed while the material of the current collector and the material of the segments are melted together. Therefore, when the volume of the weld beads is large, the current collector and the bent surface region are more strongly bonded, and the contact resistance at the welding interface becomes lower.

[0532] 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 depending on 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.

[0533] 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 weld bead is sufficient, the resistance of the welding interface can also be reduced.

[0534] 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.

[0535] The welding strength can be defined as the tensile force (kgf / cm 2 ) per unit area 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.

[0536] In the bent surface region F, the segmented pieces are laminated in a plurality of layers. According to the above-described embodiment, the number of laminated segmented pieces can increase from a minimum of 10 to a maximum of 35.

[0537] 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. Accordingly, the bent surface region F of the positive electrode may include a region where the total lamination thickness of the divided segments is 100 μm to 875 μm. Also, the bent surface region F of the negative electrode may include a region where the total lamination thickness of the divided segments is 50 μm to 700 μm.

[0538] FIG. 17f is a top view of an electrode assembly showing a lamination number average section b1 and a lamination number decreasing section b2 in the bent surface region F of the divided segments 61, 61' according to an embodiment of the present invention.

[0539] Referring to FIG. 17f, the region between the two circles indicated by the thick solid line corresponds to the bent surface region F of the divided segment, the region between the two circles indicated by the dashed-dotted line corresponds to the lamination number average section b1 where the lamination number of the divided segment is 10 or more, and the outer region of the lamination number average section b1 corresponds to the lamination number decreasing section b2.

[0540] 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 a line pattern or a dot pattern. The welding pattern W p corresponds to the welding region and can overlap with the lamination number average section b1 of the divided segment by 50% or more along the radial direction. Accordingly, a part of the welding pattern W p is included in the lamination number average section b1, and the remaining welding pattern W p can be included in the lamination number decreasing section b2 outside the lamination number average section 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 lamination number average section b1. p The whole can overlap with the lamination number average section b1.

[0541] The area of the bent surface region F can be defined as the sum of the area of the layer number average section b1 and the area of the layer number decreasing section b2 of the segment. Since the ratio (e / f) of the layer number average section b1 is 30% to 85%, preferably 31% to 82%, the ratio of the area of the layer number average 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 ).

[0542] Preferably, the end of the portion where the current collector P c contacts the bent surface region F can cover the ends of the segments 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 segments 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 segments 61, 61' laminated in the winding axis direction are tightly adhered to each other, so that the resistance at the welding interface is also reduced, and the phenomenon that the segments 61, 61' float up can be prevented.

[0543] On the other hand, the bending direction of the segment may be opposite to the above-described direction. That is, the segment may be bent from the core side to the outer peripheral side. In this case, the pattern in which the height of the segment changes along the winding direction (X-axis direction) may be opposite to the above-described embodiment (deformed form). For example, the height of the segment 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 segment is gradually decreased from the core side to the outer peripheral side, and when the segment closest to the outer periphery of the electrode assembly is bent to the outer peripheral side, the height change pattern of the segment is designed so that the end of the segment does not protrude outside the outer periphery of the electrode assembly.

[0544] The electrode structure of the above-described embodiment (variant form) can be applied to at least one of the first electrode and the second electrode with 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 (variant form) 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 are not the same and can be different.

[0545] 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 (variant forms) can be applied to the first electrode, and a conventional electrode structure (see FIG. 1) can be applied to the second electrode.

[0546] 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 (variant forms) can be selectively applied to the first electrode, and another one of the embodiments (variant forms) can be selectively applied to the second electrode.

[0547] Hereinafter, the structure of the electrode assembly according to an embodiment of the present invention will be described in detail.

[0548] FIG. 18 is a cross-sectional view of a jelly roll type electrode assembly 80 in which the electrode 40 of the first embodiment is applied to a first electrode (positive electrode) and a second electrode (negative electrode), cut along the Y-axis direction (winding axis direction).

[0549] The electrode assembly 80 can be manufactured by the winding method described with reference to FIG. 2. For convenience of explanation, the protruding structures of the first non-patterned portion 43a and the second non-patterned portion 43b extending outside the separator are shown in detail, and the illustration of the winding structure of the first electrode, the second electrode, and the separator is omitted. The first non-patterned portion 43a protruding upward extends from the first electrode, and the second non-patterned portion 43b protruding downward extends from the second electrode.

[0550] The pattern in which the heights of the first non-coated portion 43a and the second non-coated portion 43b change is schematically shown. That is, the height of the non-coated portion can change irregularly depending on the cutting position of the cross-section. As an example, if the side edges of the trapezoidal segments 61, 61' or the cutting grooves 63 are cut, the height of the non-coated portion in the cross-section becomes lower than the height H of the segments 61, 61'. Therefore, it should be understood that the height of the non-coated portion shown in the drawing showing the cross-section of the electrode assembly corresponds to the average of the heights of the non-coated portions included in each winding turn (H in FIGS. 14b and 15b).

[0551] Referring to FIG. 18, the first non-coated portion 43a includes a first portion B1 adjacent to the core of the electrode assembly 80, a second portion B3 adjacent to the outer peripheral surface of the electrode assembly 80, and a third portion B2 interposed between the first portion B1 and the second portion B3.

[0552] The height (length in the Y-axis direction) of the second portion B3 is relatively lower than the height of the third portion B2. Therefore, in the process of pressing the beading portion of the battery housing near the second portion B3, it is possible to prevent the phenomenon that the beading portion and the second portion B3 come into contact with each other and cause an internal short circuit.

[0553] The second non-coated portion 43b has the same structure as the first non-coated portion 43a. In a variant form, the second non-coated portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (variant forms).

[0554] The ends 81 of the first non-coated portion 43a and the second non-coated portion 43b can be bent from the radial direction of the electrode assembly 80, for example, from the outer peripheral side to the core side. At this time, the second portion B3 may not be substantially bent.

[0555] FIG. 19 is a cross-sectional view of a jelly roll type electrode assembly 90 in which the electrode 45 of the second embodiment is applied to a first electrode (positive electrode) and a second electrode (negative electrode), cut along the Y-axis direction (winding axis direction).

[0556] Referring to FIG. 19, the first non-coated portion 43a of the first electrode includes a first portion B1 adjacent to the core of the electrode assembly 90, a second portion B3 adjacent to the outer peripheral surface of the electrode assembly 90, and a third portion B2 interposed between the first portion B1 and the second portion B3.

[0557] The height of the second portion B3 is relatively lower than the height of the third portion B2, and gradually or stepwise decreases from the core side toward the outer peripheral side. Therefore, it is possible to prevent a phenomenon in which the beading portion of the battery housing comes into contact with the second portion B3 during the process of being pressed in the vicinity of the second portion B3, causing an internal short circuit.

[0558] The second non-coated portion 43b has the same structure as the first non-coated portion 43a. In one variant form, the second non-coated portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (variant forms).

[0559] The ends 91 of the first non-coated portion 43a and the second non-coated portion 43b can be bent in the radial direction of the electrode assembly 90, for example, from the outer peripheral side to the core side. At this time, the outermost side 92 of the second portion B3 may not be substantially bent.

[0560] FIG. 20 is a cross-sectional view of a jelly roll type electrode assembly 100 in which any one of the electrodes 50, 60, 70 of the third to fifth embodiments (these variant forms) is applied to the first electrode (positive electrode) and the second electrode (negative electrode), cut along the Y-axis direction (winding axis direction).

[0561] Referring to FIG. 20, the non-coated 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.

[0562] The height of the first part B1 is relatively lower than the height of the third part B2. Also, in the third part B2, the bending length of the plain part 43a located innermost is the same as or shorter than the radial length R of the first part B1. The bending length H corresponds to the distance from the point where the plain part 43a is bent to the upper end of the plain part 43a. In a modified example, the bending length H can be smaller than the value obtained by adding the radial length R of the first part B1 and 10% of the radius of the core 102.

[0563] Therefore, even when the third part B2 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 on the negative electrode (or positive electrode) side and the battery housing (or terminal).

[0564] The height of the second part B3 is relatively lower than the height of the third part B2. Therefore, it is possible to prevent the phenomenon that the beading part and the second part B3 come into contact with each other and cause an internal short circuit during the process of pressing the beading part of the battery housing near the second part B3.

[0565] In one modified form, the height of the second part B3 can gradually or stepwise decrease, different from the illustration in FIG. 20. Also, in FIG. 20, the height of the third part B2 is equal in a part on the outer peripheral side, but the height of the third part B2 can gradually or stepwise increase 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. When the third part B2 is divided into a plurality of segments, the section where the height of the plain part 43a changes corresponds to the height variable section of the segment (circle 2 in FIG. 17a).

[0566] The second plain part 43b has the same structure as the first plain part 43a. In one modified form, the second plain part 43b may have a conventional electrode structure or an electrode structure of other embodiments (modified forms).

[0567] The ends 101 of the first non-land portion 43a and the second non-land portion 43b 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 first portion B1 and the second portion B3 are not substantially bent.

[0568] When the third portion B2 includes a plurality of divided segments, the bending stress is relaxed, so that it is possible to prevent the non-land portion 43a near the bending point from being broken or abnormally deformed. Further, when the width and / or height and / or separation pitch of the divided segments are adjusted within the numerical range of the above-described embodiments, the divided segments overlap multiply to such an extent that sufficient welding strength can be ensured while being bent toward the core side, and do not form a space (gap) in the bent surface region.

[0569] FIG. 21 is a cross-sectional view of the electrode assembly 110 according to still another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0570] Referring to FIG. 21, the electrode assembly 110 has substantially the same other configuration as the electrode assembly 100 of FIG. 20, except that the height of the second portion B3 is substantially the same as the outermost height of the third portion B2.

[0571] The second portion B3 may include a plurality of divided segments. The configuration of the plurality of divided segments is substantially the same as that of the fourth and fifth embodiments (modification forms) related to the electrodes.

[0572] In the electrode assembly 110, the height of the first portion B1 is relatively lower than the height of the third portion B2. Further, the bending length H of the non-land portion located innermost in the third portion B2 is the same as or shorter than the radial length R of the first portion B1. Preferably, the first portion B1 may be a divided segment omission section (circle 1 in FIG. 17a) without divided segments. In a modification, the bending length H may be smaller than the value obtained by adding the radial length R of the first portion B1 and 10% of the radius of the core 112.

[0573] Therefore, even when the third portion B2 is bent, at least 90% of the diameter of the core 112 of the electrode assembly 110 is open 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, and the welding process between the current collector on the negative electrode (or positive electrode) side and the battery housing (or terminal) can be easily performed.

[0574] In one variant, the structure in which the height of the third portion B2 gradually or stepwise increases from the core side toward the outer peripheral side can be extended to the second portion B3. In this case, the height of the plain portion 43a 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.

[0575] The second plain portion 43b has the same structure as the first plain portion 43a. In one variant, the second plain portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (variants).

[0576] The ends 111 of the first plain portion 43a and the second plain portion 43b 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 first portion B1 is not substantially bent.

[0577] When the third portion B2 and the second portion B3 include a plurality of segmented pieces, since the bending stress is relaxed, it is possible 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 segmented pieces are adjusted within the numerical range of the above-described embodiments, the segmented pieces are overlapped multiple times to ensure sufficient welding strength while being bent toward the core side, and do not form a space (gap) in the bent surface area.

[0578] FIG. 22 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).

[0579] Referring to FIG. 22, the electrode assembly 120 is different only in that the height of the third portion B2 has a pattern of gradually or stepwise increasing and then decreasing compared to the electrode assembly 100 of FIG. 20, and the other configurations are substantially the same. The radius interval in which the height of the third portion B2 changes can be regarded as the height variable interval of the segment (circle 2 in FIG. 17a). Also in this case, the height variable interval of the segment can be designed such that a layer number uniform interval where the number of stacked segments is 10 or more appears in the bending surface region F formed while the third portion B2 is bent within the above-described preferable numerical range.

[0580] Such a change in the height of the third portion B2 can be realized by adjusting the height of the step pattern (see FIG. 14c) or the segment (see FIG. 14d or FIG. 15a) included in the third portion B2.

[0581] In the electrode assembly 120, the height of the first portion B1 is relatively lower than the height of the third portion B2. Also, the bending length H of the plain portion located innermost in the third portion B2 is the same as or shorter than the radial length R of the first portion B1. The section corresponding to the first portion B1 corresponds to the segment omission section (circle 1 in FIG. 17a) without segments. In a modified example, the bending length H can be smaller than the value obtained by adding the radial length R of the first portion B1 and 10% of the radius of the core 102.

[0582] Therefore, even when the third portion B2 is bent toward the core side, the core 122 of the electrode assembly 120 is opened to the outside by 90% or more of its diameter. 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 on the negative electrode (or positive electrode) side and the battery housing (or terminal) can be easily performed.

[0583] Also, the height of the second part B3 is relatively lower than the height of the third part B2, and preferably, no slitting section needs to be formed in the second part B3. Therefore, in the process of the beading part of the battery housing being pressed near the second part B3, it is possible to prevent the phenomenon of internal short - circuit from occurring while the beading part and the second part B3 come into contact with each other. In a modified example, the height of the second part B3 may gradually or step - by - step decrease toward the outer peripheral side.

[0584] The second non - textured part 43b has the same structure as the first non - textured part 43a. In a modified example, the second non - textured part 43b may have a conventional electrode structure or an electrode structure of other embodiments (modified forms).

[0585] The end portions 121 of the first non - textured part 43a and the second non - textured part 43b can be bent from the outer peripheral side of the electrode assembly 120 toward the core side. At this time, the first part B1 and the second part B3 are not substantially bent.

[0586] When the third part B2 includes a plurality of slitting sections, since the bending stress is relaxed, it is possible to prevent the non - textured parts 43a and 43b from being torn or abnormally deformed. Also, when the width and / or height and / or separation pitch of the slitting sections are adjusted within the numerical range of the above - described embodiments, the slitting sections are folded toward the core side while overlapping multiple times to ensure sufficient welding strength and do not form a space (gap) in the bent surface area.

[0587] FIG. 23 is a cross - sectional view of the electrode assembly 130 according to still another embodiment of the present invention, cut along the Y - axis direction (winding axis direction).

[0588] Referring to FIG. 23, the electrode assembly 130 is different from the electrode assembly 120 of FIG. 22 in that the height of the second part B3 has a pattern of gradually or step - by - step decreasing from the boundary point between the second part B3 and the third part B2 toward the outermost surface of the electrode assembly 130, and other configurations are substantially the same.

[0589] Such a height change of the second part B3 can be realized by extending the staircase pattern (see FIG. 14c) included in the third part B2 to the second part B3 and gradually or stepwise decreasing the height of the pattern toward the outer peripheral side. Further, in another modification, the height change of the second part B3 can be realized by extending the segmented structure of the third part B2 to the second part B3 and gradually or stepwise decreasing the height of the segments toward the outer peripheral side.

[0590] In the electrode assembly 130, the height of the first part B1 is relatively lower than the height of the third part B2. Also, the bending length H of the plain part located innermost in the third part B2 is the same as or shorter than the radial length R of the first part B1. The first part B1 corresponds to a segment-omitted section (circle 1 in FIG. 17a) without segments. In a modification, the bending length H can be smaller than the value obtained by adding the radial length R of the first part B1 and 10% of the radius of the core 102.

[0591] Therefore, even when the third part B2 is bent toward the core side, 90% or more of the diameter of the core 132 of the electrode assembly 130 is open 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 on the negative electrode (or positive electrode) side and the battery housing (or terminal) can be easily performed.

[0592] The second plain part 43b has the same structure as the first plain part 43a. In one variant form, the second plain part 43b may have a conventional electrode structure or an electrode structure of other embodiments (variant forms).

[0593] The end portions 131 of the first plain part 43a and the second plain part 43b can be bent from the outer peripheral side to the core side of the electrode assembly 130. At this time, the first part B1 is not substantially bent.

[0594] When the third part B2 and the second part B3 include a plurality of divided sections, since the bending stress is relaxed, it is possible 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 divided sections are adjusted within the numerical range of the above-described embodiments, the divided sections are overlapped multiple times to a sufficient extent to ensure the welding strength while being bent toward the core side, and do not form a space (gap) in the bent surface region.

[0595] On the other hand, in the above-described embodiments (deformed forms), the ends of the first plain portion 43a and the second plain portion 43b can be bent from the core side toward the outer peripheral side. In this case, the second part B3 is designed as a divided section omission section (circle 1 in FIG. 17a) without a divided section, and it is preferable that it is not bent toward the outer peripheral side. Further, the radial width of the second part B3 can be the same as or larger than the length at which the outermost plain portion (or divided section) of the third part B2 is bent. Thereby, when the outermost plain portion (or divided section) of the third part B2 is bent toward the outer peripheral side, the end of the bent portion does not protrude beyond the outer peripheral surface of the electrode assembly toward the inner surface of the battery housing. Further, the change pattern of the divided section structure may be opposite to that of the above-described embodiments (deformed forms). For example, the height of the divided section can be increased stepwise or gradually from the core side toward the outer peripheral side. That is, by arranging a divided section omission section (circle 1 in FIG. 17a), a divided section height variable section (circle 2 in FIG. 17a), and a divided section height uniform section (circle 3 in FIG. 17a) 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 divided sections is 10 or more may appear in a preferable numerical range in the bent surface region.

[0596] The structures of various electrode assemblies according to the embodiments of the present invention are applicable to cylindrical batteries.

[0597] Preferably, the cylindrical battery can be a cylindrical battery having a form factor ratio (a value obtained by dividing the diameter of the cylindrical battery by its height, i.e., defined by the ratio of height (H) to outer diameter (Φ)) greater than about 0.4. Here, the form factor means a value indicating the diameter and height of the cylindrical battery.

[0598] Preferably, the diameter of the cylindrical battery can be 40 mm to 50 mm, and the height can be 60 mm to 130 mm. The form factor of the cylindrical battery according to one embodiment can be, for example, 46110, 4875, 48110, 4880, 4680, or 4695. 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. The number of winding turns of the electrode assembly can be 50 turns to 60 turns.

[0599] 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 non-coated portion is large, and the non-coated portion is likely to break. Also, when welding the current collector to the bent surface area of the non-coated portion, in order to sufficiently ensure the welding strength and reduce the resistance, the number of laminations of the non-coated portion 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.

[0600] A battery according to one 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.

[0601] A 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.

[0602] Batteries according to yet other embodiments can be cylindrical batteries that are substantially cylindrical in shape, have a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.436.

[0603] Batteries according to yet other embodiments can be cylindrical batteries that are substantially cylindrical in shape, have a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0604] Batteries according to yet other embodiments can be cylindrical batteries that are substantially cylindrical in shape, have a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0605] Batteries according to yet other embodiments can be cylindrical batteries that are substantially cylindrical in shape, have a diameter of about 46 mm, a height of about 95 mm, and a form factor ratio of 0.484.

[0606] Conventionally, batteries with 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 an 1865 battery, its diameter is about 18 mm, its height is about 65 mm, and its form factor ratio is 0.277. In the case of a 2170 battery, the diameter is about 21 mm, the height is about 70 mm, and the form factor ratio is 0.300.

[0607] Hereinafter, a cylindrical battery according to an embodiment of the present invention will be described in detail.

[0608] FIG. 24 is a cross-sectional view of a cylindrical battery 140 according to an embodiment of the present invention cut along the Y-axis direction.

[0609] Referring to FIG. 24, a cylindrical battery 140 according to an embodiment of the present invention includes an electrode assembly 141 including a first electrode, a separator, and a second electrode, a battery housing 142 housing the electrode assembly 141, and a sealing member 143 sealing an open end of the battery housing 142.

[0610] 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 141 in the inner space through the upper end opening, and also houses the electrolyte together.

[0611] The electrolyte may be a salt having a structure such as A + B - . Here, A + includes ions composed of alkali metal cations such as Li + , Na + , K + , or a combination thereof. And B - is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , BF2C2O4 - , BC4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (CF3SO2)2N -, (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - It contains any one or more anions selected from the group consisting of.

[0612] 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.

[0613] The electrode assembly 141 can have a jelly-roll structure, but the present invention is not limited thereto. As shown in FIG. 2, the electrode assembly 141 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 shaft C.

[0614] 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 can have the electrode structure according to the above-described embodiment (modified form). Also, the other of the first electrode and the second electrode can have a conventional electrode structure or an electrode structure according to an embodiment (modified form). The number of electrode pairs included in the electrode assembly 141 is not limited to one and can be two or more.

[0615] From the upper and lower parts of the electrode assembly 141, the first plain part 146a of the first electrode and the second plain part 146b of the second electrode project respectively. The first electrode has the electrode structure of the first embodiment (deformed form). Therefore, the height of the second part B3 of the first plain part 146a is lower than that of the plain parts of other parts. The second part B3 is spaced apart from the inner peripheral surface of the battery housing 142, particularly the beading part 147, by a predetermined distance. Therefore, since the second part B3 of the first electrode does not contact the battery housing 142 electrically connected to the second electrode, an internal short circuit of the cylindrical battery 140 is prevented.

[0616] The second plain part 146b of the second electrode may have the same structure as the first plain part 146a. In other deformed forms, the second plain part 146b may selectively have the structure of the plain part of the electrode according to the embodiment (deformed form).

[0617] The sealing body 143 may include a cap 143a having a plate shape, a first gasket 143b that provides airtightness between the cap 143a and the battery housing 142 and has insulation properties, and a connecting plate 143c electrically and mechanically coupled to the cap 143a.

[0618] The cap 143a is a component made of a conductive metal material and covers the upper end opening of the battery housing 142. The cap 143a is electrically connected to the first plain part 146a of the first electrode and is electrically insulated from the battery housing 142 through the first gasket 143b. Therefore, the cap 143a can function as the first electrode terminal (for example, the positive electrode) of the cylindrical battery 140.

[0619] The cap 143a is placed on the beading portion 147 formed on the battery housing 142 and fixed by a crimping portion 148. A first gasket 143b may be interposed between the cap 143a and the crimping portion 148 to ensure the airtightness of the battery housing 142 and the electrical insulation between the battery housing 142 and the cap 143a. The cap 143a may include a protruding portion 143d formed to protrude upward from its central portion.

[0620] The battery housing 142 is electrically connected to the second non-textured portion 146b 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.

[0621] The battery housing 142 includes a beading portion 147 and a crimping portion 148 at its upper end. The beading portion 147 is formed by pushing 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 141 housed inside the battery housing 142 does not come out from the upper end opening of the battery housing 142.

[0622] The inner peripheral surface of the beading portion 147 is separated from the second portion B3 of the first electrode by a predetermined distance. More specifically, the lower end of the inner peripheral surface of the beading portion 147 is separated from the second portion B3 of the first electrode by a predetermined distance. Also, since the second portion B3 has a low height, it is not substantially affected even when the battery housing 142 is pushed in from the outside to form the beading portion 147. Therefore, the second portion B3 is not compressed by other components such as the beading portion 147, thereby preventing the occurrence of partial deformation of the electrode assembly 141 and preventing an internal short circuit of the cylindrical battery 140.

[0623] 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 second portion B3 is substantially prevented.

[0624] The crimping portion 148 is formed above 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 143a disposed on the beading portion 147 and a part of the upper surface of the cap 143a.

[0625] The cylindrical battery 140 may further include a first current collector 144 and / or a second current collector 145 and / or an insulator 146.

[0626] The first current collector 144 is coupled to the upper portion of the electrode assembly 141. The first current collector 144 is made of a metal material having conductivity such as aluminum, copper, steel, nickel, etc., and is electrically connected to the first non-coated portion 146a of the first electrode. The electrical connection can be made through welding. A lead 149 may be coupled to the first current collector 144. The lead 149 may extend above the electrode assembly 141 and be coupled to the connection plate 143c, or may be directly coupled to the lower surface of the cap 143a. The connection between the lead 149 and other components can be made through welding.

[0627] 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 center portion of the first current collector 144.

[0628] The first current collector 144 may be provided with a plurality of concavo-convex portions (not shown) formed radially on its lower surface. When the radial concavo-convex portions are provided, the first current collector 144 can be pressed to push the first non-coated portion 146a of the first electrode into the concavo-convex portions.

[0629] The first current collector 144 is coupled to the end of the first non-patterned portion 146a. The coupling between the first non-patterned portion 146a and the first current collector 144 can be performed, for example, by laser welding. The laser welding can be performed in a manner that partially melts the base material of the first current collector 144. In a modified example, the welding between the first current collector 144 and the first non-patterned portion 146a can be performed with solder interposed therebetween. In this case, the solder can have a melting point lower than that of the first current collector 144 and the first non-patterned portion 146a. The laser welding can be replaced with resistance welding, ultrasonic welding, spot welding, etc.

[0630] A second current collector 145 can be coupled to the lower surface of the electrode assembly 141. One surface of the second current collector 145 can be c...

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, defining a core and an outer peripheral surface, a cylindrical battery housing for housing the electrode assembly, comprising: When, on a cross-section of the electrode assembly perpendicular to the winding axis direction, a first sector region surrounded by a first straight line passing from the center of the core through the core-side end of the first electrode, a second straight line passing from the center of the core through the core-side end of the second electrode, and the outer peripheral surface is defined as a stress vulnerable region, and a second sector region surrounded by a third straight line passing from the center of the core through the outer peripheral-side end of the first electrode, a fourth straight line passing from the center of the core through the outer peripheral-side end of the second electrode, and the outer peripheral surface is defined as a stress amplification region, The electrode assembly has a winding structure in which at least the outer peripheral-side end of the first electrode in the stress amplification region is separated from the inside of the stress vulnerable region along the circumferential direction, a cylindrical battery.

2. The cylindrical battery according to claim 1, wherein an outer peripheral region of the electrode assembly where the outer peripheral-side end of the first electrode is located is in close contact with the inner surface of the battery housing.

3. The cylindrical battery according to claim 1, wherein the electrode assembly has a winding structure in which the stress amplification region is separated from the stress vulnerable region along the circumferential direction on the cross-section.

4. When, on the cross-section, the cross-section is divided into a first semi-circular region and a second semi-circular region with reference to a diameter line segment passing through the center of the core and perpendicular to a straight line that equally divides the central angle of the stress vulnerable region at an equal angle, The cylindrical battery according to claim 1, wherein the electrode assembly has a winding structure in which the stress vulnerable region is located in the first semi-circular region and the stress amplification region is located in the second semi-circular region.

5. The cylindrical battery according to claim 4, wherein the electrode assembly has a winding structure in which at least a part of the stress amplification region overlaps with a third sector region in the second semi-circular region that is point-symmetrical with the stress vulnerable region with reference to the center of the core.

6. The cylindrical battery according to claim 5, wherein the electrode assembly has a winding structure in which at least a part of the stress amplification region overlaps with a fifth straight line that equally divides the central angle of the third sector region at an equal angle.

7. When a fifth straight line is a straight line that equally divides a third sector region that is point-symmetrical to the stress vulnerable region with respect to the center of the core, The electrode assembly has a winding structure in which the third straight line and the fourth straight line are positioned between the second straight line and the fifth straight line with respect to the circumferential direction on the cross section, The cylindrical battery according to claim 1.

8. When a fifth straight line is a straight line that equally divides a third sector region that is point-symmetrical to the stress vulnerable region with respect to the center of the core, The electrode assembly has a winding structure in which the third straight line and the fourth straight line are positioned between the first straight line and the fifth straight line with respect to the circumferential direction on the cross section, The cylindrical battery according to claim 1.

9. When a fifth straight line is a straight line that equally divides a third sector region that is point-symmetrical to the stress vulnerable region with respect to the center of the core, The electrode assembly has a winding structure in which the fourth straight line is positioned between the fifth straight line and the first straight line and the third straight line is positioned between the fourth straight line and the second straight line with respect to the circumferential direction on the cross section, The cylindrical battery according to claim 1.

10. When a fifth straight line is a straight line that equally divides a third sector region that is point-symmetrical to the stress vulnerable region with respect to the center of the core, The electrode assembly has a winding structure in which the fourth straight line is positioned between the fifth straight line and the first straight line and the third straight line is positioned between the fifth straight line and the second straight line with respect to the circumferential direction on the cross section, The cylindrical battery according to claim 1.

11. When a fifth straight line is a straight line that equally divides a third sector region that is point-symmetrical to the stress vulnerable region with respect to the center of the core, The electrode assembly has a winding structure in which the fourth straight line is positioned between the fifth straight line and the second straight line and the third straight line is positioned between the fourth straight line and the first straight line with respect to the circumferential direction on the cross section, The cylindrical battery according to claim 1.

12. When a fifth straight line is a straight line that equally divides a third sector region that is point-symmetrical to the stress vulnerable region with respect to the center of the core, The electrode assembly has a winding structure in which the fourth straight line is positioned between the fifth straight line and the second straight line and the third straight line is positioned between the fifth straight line and the first straight line with respect to the circumferential direction on the cross section, The cylindrical battery according to claim 1.

13. The electrode assembly has a winding structure in which, based on the circumferential direction in the cross section, the central angle between the first straight line and the fourth straight line is larger than the central angle between the second straight line and the third straight line. The cylindrical battery according to claim 1.

14. The electrode assembly has a winding structure in which, based on the circumferential direction in the cross section, the central angle between the second straight line and the fourth straight line is larger than the central angle between the first straight line and the third straight line. The cylindrical battery according to claim 1.

15. The electrode assembly has a winding structure in which, based on the center of the core, the central angle of the stress amplification region is smaller than the central angle of the stress vulnerable region. The cylindrical battery according to claim 1.

16. The winding structure of the electrode assembly is maintained while being charged and discharged 200 cycles or more, 300 cycles or more, 400 cycles or more, 500 cycles or more, 600 cycles or more, 700 cycles or more, 800 cycles or more, or 900 cycles or more. The cylindrical battery according to any one of claims 1 to 15.

17. The first electrode and the second electrode are a positive electrode and a negative electrode, respectively. At least a part of the winding turns of the negative electrode consisting only of the second electrode is provided adjacent to the core side. At least a part of the winding turns of the negative electrode in which the winding turns facing each other in the radial direction are winding turns of the negative electrode. The cylindrical battery according to claim 1.

18. A plurality of winding turns consisting only of the separator are provided inside the winding turns of the negative electrode. The cylindrical battery according to claim 17.

19. The first electrode and the second electrode are a positive electrode and a negative electrode, respectively. The core-side end portion of the second electrode extends further in the direction opposite to the winding direction of the electrode assembly than the core-side end portion of the first electrode and forms at least a part of the innermost winding turn. The outer peripheral side end portion of the second electrode extends further in the winding direction than the outer peripheral side end portion of the first electrode and forms at least a part of the outermost winding turn. The cylindrical battery according to claim 1.

20. The electrode assembly has a winding structure in which the central angle of the stress vulnerable region has an angle of 30° or more and less than 180°, and the central angle of the stress amplification region has an angle of 10° or more and 90° or less. The cylindrical battery according to claim 1.

21. The electrode assembly body has a winding structure in which the central angle of the stress vulnerable region has an angle of 87° or more, and the central angle of the stress amplification region has an angle of 32° or less. The cylindrical battery according to claim 20.

22. The battery housing includes an open end and a bottom portion facing the open end, and houses the electrode assembly body in a space between the open end and the bottom portion, and is electrically connected to one of the first electrode and the second electrode to have a first polarity. The cylindrical battery according to claim 1.

23. A sealing body for sealing the open end of the battery housing; A terminal electrically connected to the other of the first electrode and the second electrode and having a second polarity with its surface exposed to the outside. The cylindrical battery according to claim 22.

24. The first electrode includes a first plain portion at a long side end along the winding direction of the electrode assembly body. The first plain portion extends and protrudes outside the separator through one side end of the electrode assembly body, and is bent in the radial direction of the electrode assembly body to form a first bent surface region. The cylindrical battery according to claim 1, further including a first current collector welded to the first bent surface region.

25. The first plain portion includes a plurality of segmented pieces along the winding direction of the electrode assembly body. The cylindrical battery according to claim 24, wherein the plurality of segmented pieces are bent in the radial direction of the electrode assembly body to form the first bent surface region.

26. The second electrode includes a second plain portion at a long side end along the winding direction of the electrode assembly body. The second plain portion extends and protrudes outside the separator through the other side end of the electrode assembly body, and is bent toward the core side to form a second bent surface region. The cylindrical battery according to claim 1, further including a second current collector welded to the second bent surface region.

27. The second plain portion includes a plurality of segmented pieces along the winding direction of the electrode assembly body. The cylindrical battery according to claim 26, wherein the plurality of segmented pieces are bent in the radial direction of the electrode assembly body to form the second bent surface region.

28. The welding region of the first current collector has a radial structure. The cylindrical battery according to claim 24 or 25.

29. The welding region of the second current collector has a radial structure. The cylindrical battery according to claim 26 or 27.

30. The ratio of the height to the diameter of the cylindrical battery is greater than 0.

4. The cylindrical battery according to claim 1. Claim 31 The cylindrical battery according to claim 30, wherein the form factor of the cylindrical battery is 46110, 4875, 48110, 4880, 4680 or 4695. Claim 32 A battery pack including a plurality of the cylindrical batteries according to claim 1. Claim 33 An automobile including the battery pack according to claim 32.

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