Electrode assembly and battery cell having same

Abstract

Provided is an electrode assembly capable of suppressing or preventing deterioration or shortening of the lifespan of a battery cell caused by expansion or contraction behavior during charging and discharging. The electrode assembly is manufactured in a jelly-roll form in which a first electrode and a second electrode are wound around a winding axis along the longitudinal direction with a separator interposed therebetween. At the outer circumferential end portion of at least one of the first electrode and the second electrode, both end portions in the width direction extend further toward the outer circumferential side along the longitudinal direction than the central portion in the width direction of the electrode, the width direction intersecting the longitudinal direction.

Description

Electrode assembly and battery cell equipped with the same

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0194741 filed on December 23, 2024, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0002] The present invention relates to an electrode assembly and a battery cell equipped with the same, and more specifically, to a technology for suppressing or preventing the phenomenon in which a battery cell deteriorates or its lifespan is shortened due to the behavior of an electrode assembly wound in a jelly-roll form expanding or contracting during charging and discharging.

[0003] Secondary batteries are classified according to the shape of the battery case into cylindrical batteries, in which the electrode assembly is housed in a cylindrical metal can; prismatic batteries, in which the electrode assembly is housed in a rectangular metal can; and pouch batteries, in which the electrode assembly is housed in a pouch-type case made of aluminum laminate sheets. Among these, cylindrical batteries have the advantages of a simple manufacturing process and structural stability.

[0004] The electrode assembly embedded in the battery case is a chargeable device composed of a stacked structure of a positive electrode, a separator, and a negative electrode, and is classified into jelly-roll type, stack type, and folding type. The jelly-roll type is a form in which a separator is interposed between a long sheet-type positive electrode and a negative electrode coated with an active material and wound; it is easy to manufacture and has a high energy density per unit weight.

[0005] Recently, as the need for batteries to achieve high capacity and high output has increased, cylindrical batteries are becoming larger. When cylindrical batteries become larger, the electrodes become longer in the longitudinal direction, and the number of turns of the electrode winding increases.

[0006] Meanwhile, electrodes, particularly the negative electrode, undergo expansion or contraction due to battery reactions such as charging and discharging. However, while the clearance provided inside the can when the electrode assembly of a large cylindrical battery is housed in the can remains almost unchanged compared to that of a small cylindrical battery, the length of the electrode and the number of turns of the large electrode assembly are significantly longer and greater compared to the length of the electrode and the number of turns of the small electrode assembly. In other words, the amount of expansion and contraction of the electrode during the charging and discharging process of a large cylindrical battery is significantly greater than that of a small cylindrical battery.

[0007] Furthermore, when manufacturing large cylindrical batteries, the rolling pressure of the active material coated on the current collector is increased to increase energy density. As a result, the active material has a higher density, and thus, the gas generated during the activation process of the secondary battery is trapped in the pores of the active material and cannot escape easily.

[0008] Due to these various factors, it has been reported that during the activation and use of large cylindrical battery cells, the central portion in the vertical direction of the electrode assembly expands more than the ends. This phenomenon increases the internal pressure in the central portion of the electrode assembly, leading to degradation of the assembly and consequently causing a reduction in the battery cell's lifespan.

[0009] The present invention has been devised to solve the aforementioned problems and aims to provide an electrode assembly with a structure that prevents excessive pressure from occurring in the electrode assembly by resolving the imbalance of internal pressure applied to the electrode assembly due to the expansion and contraction of the electrode assembly during the charging and discharging process of the secondary battery, and a cylindrical secondary battery to which the same is applied.

[0010] The present invention aims to generalize the expansion and contraction behavior of an electrode assembly occurring during the charging and discharging process of a secondary battery, and to provide a method for resolving the imbalance of internal pressure applied to the electrode assembly in response to such behavior.

[0011] The present invention aims to provide an electrode assembly structure capable of suppressing the deterioration of the roundness and cylindricality of a jelly-roll caused by the expansion and contraction behavior of the electrode assembly during the charging and discharging process of a secondary battery.

[0012] The present invention aims to provide an electrode assembly and a battery cell structure with high energy density while providing a margin for the electrode assembly to expand.

[0013] The technical problems of the present invention are not limited to the purposes mentioned above, and other unmentioned purposes and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the purposes and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0014] The present invention can be applied to a battery cell comprising an electrode assembly and a case that accommodates the electrode assembly.

[0015] The above electrode assembly may be in the form of a jelly-roll in which a first electrode and a second electrode are wound along the longitudinal direction with a separator in between.

[0016] The jelly-roll may be cylindrical, wound around a core axis. Accordingly, the outer circumference of the electrode assembly may be substantially circular.

[0017] The above-mentioned core shaft may have a circular pin shape. Accordingly, the hollow portion of the core of the electrode assembly may be substantially circular.

[0018] In the above longitudinal direction, the first electrode may be longer than the second electrode.

[0019] In the above winding direction, the first electrode may be extended further inward in the longitudinal direction than the second electrode at the core side end, or the first electrode may begin to be wound before the second electrode in the above winding direction.

[0020] Preferably, the winding can be performed in a form where the second electrode is stacked closer to the core side than the first electrode.

[0021] Preferably, a separator may be disposed at the core-side end of the electrode assembly in the winding direction.

[0022] In the above winding direction, the first electrode may be extended further outward in the longitudinal direction than the second electrode at the outer end, or the second electrode may not cover the outer end of the first electrode in the winding direction at the radial outer side.

[0023] The first electrode may be in the form in which a first active material is coated on the surface of a first current collector.

[0024] Preferably, the first electrode may be a negative electrode.

[0025] Preferably, the first current collector may be a metal foil containing copper material.

[0026] The second electrode may be in the form in which a second active material is coated on the surface of a second current collector.

[0027] Preferably, the second electrode may be an anode.

[0028] Preferably, the second current collector may be a metal foil containing aluminum material.

[0029] The first electrode may have a first electrode tab protruding axially from the electrode assembly toward a first end.

[0030] Preferably, a first non-exposed portion in which the surface of the first current collector is exposed may be disposed at the first axial end of the electrode assembly.

[0031] Preferably, at least a portion of the first non-removable portion can provide the first electrode tab.

[0032] The second electrode may have a second electrode tab protruding axially from the electrode assembly toward a second end.

[0033] Preferably, a second non-removable portion in which the surface of the second current collector is exposed may be disposed at the axial second end of the electrode assembly.

[0034] Preferably, at least a portion of the second non-removable portion can provide the second electrode tab.

[0035] To solve the above-mentioned problem, the present invention provides an electrode assembly in which at least one of a first electrode and a second electrode has an outer circumferential end in the longitudinal direction, and both ends in the width direction extend further outward along the longitudinal direction than the central part in the width direction of the electrode that intersects the longitudinal direction.

[0036] The longitudinal outer end of at least one electrode may include an innermost end disposed at the center of the width direction of the electrode and provided at the innermost end in the longitudinal direction, and a pair of outermost ends disposed at both ends of the width direction of the electrode and provided at the outermost end in the longitudinal direction.

[0037] The widthwise lengths of each of the pair of outermost ends of the outer circumference of the electrode, measured in the axial direction of the electrode assembly, may correspond to each other or differ from each other.

[0038] The width direction of the electrode may correspond to or be parallel to the axial direction of the electrode assembly. The axial direction of the electrode assembly may correspond to the height direction of the electrode assembly. The length direction of the electrode may correspond to the circumferential direction of the electrode assembly.

[0039] Preferably, the widthwise length of each outermost end may be 0.1 or more and 0.3 or less relative to the axial length of the electrode assembly.

[0040] Additionally, the outer end of the electrode may further include a pair of connecting ends connecting the innermost end and a pair of outermost ends, respectively.

[0041] Preferably, each connecting end may have at least one of a horizontal section extending parallel to the longitudinal direction as it extends outward in the longitudinal direction of the electrode, and an inclined section extending obliquely toward the outer side in the width direction of the electrode as it extends outward in the longitudinal direction of the electrode.

[0042] That is, the above connecting end may have one or more horizontal sections, one or more inclined sections, or one or more horizontal sections and one or more inclined sections.

[0043] Preferably, each slope section may comprise at least one of a concave slope section in which the degree of extension toward the width direction gradually decreases as it extends toward the longitudinal outer side, a linear slope section in which it extends uniformly toward the width direction, and a convex slope section in which the degree of extension toward the width direction gradually increases.

[0044] That is, a slope section may include a linear slope section, a concave slope section, a convex slope section, a linear slope section and a concave slope section, a linear slope section and a convex slope section, a concave slope section and a convex slope section, or a concave slope section, a linear slope section, and a convex slope section.

[0045] One or more slope sections provided by the above-mentioned connecting end may include a concave slope section and a linear slope section. The linear slope section may be positioned further outward in the longitudinal direction than the concave slope section.

[0046] One or more inclined sections provided by the above-mentioned connecting end may include a concave inclined section and a convex inclined section. The convex inclined section may be positioned further outward in the longitudinal direction than the concave inclined section.

[0047] One or more inclined sections provided by the above-mentioned connecting end may include a linear inclined section and a convex inclined section. The convex inclined section may be positioned further outward in the longitudinal direction than the linear inclined section.

[0048] Preferably, the step center angle with respect to the center of the electrode assembly, which is occupied by the step section between the innermost end and the outermost end in the longitudinal direction of the electrode, may be 30 degrees or more and 720 degrees or less.

[0049] In some embodiments, the axial height of the electrode assembly may be 70 mm to 110 mm.

[0050] In some embodiments, the diameter of the electrode assembly may be 40 mm to 48 mm.

[0051] Preferably, along the longitudinal direction of the electrode, the step distance between the innermost end and the outermost end may be 20 mm or more and 480 mm or less.

[0052] In some embodiments, at least one electrode may be a first electrode. That is, the outer end of the first electrode may extend further along the length direction toward the outer edge than the central portion in the width direction. Additionally, the outer end of the second electrode may extend substantially parallel to the axial direction of the electrode assembly. Preferably, the innermost end of the outer end of the first electrode may be positioned further toward the outer edge than the outer end of the second electrode.

[0053] More preferably, the center angle of the step may be 60 degrees or less.

[0054] More preferably, the step distance may be 40 mm or less.

[0055] In some embodiments, at least one electrode may be a first electrode and a second electrode. That is, the outer end portions of each of the first electrode and the second electrode may extend further along the length direction toward the outer side than the central portion of the electrode in the width direction intersecting the length direction. Preferably, the first electrode and the second electrode may satisfy at least one of a first condition in which the innermost end portion of the outer end portion of the first electrode is positioned further toward the outer side than the innermost end portion of the outer end portion of the second electrode, a second condition in which the outermost end portion of the first electrode is positioned further toward the outer side than the outermost end portion of the second electrode, and a third condition in which the connecting end portion of the outer end portion of the first electrode is positioned further toward the outer side than the connecting end portion of the outer end portion of the second electrode, and more preferably, all conditions may be satisfied.

[0056] More preferably, the center angle of the step may be 60 degrees or more.

[0057] More preferably, the step distance may be 40mm or more.

[0058] More preferably, the central angle may be 360 ​​degrees or less.

[0059] More preferably, the above step distance may be 240 mm or less.

[0060] In some embodiments, the first non-removable portion may be electrically connected by being joined to a first current collector plate disposed at the first axial end of the electrode assembly.

[0061] In some embodiments, the second non-electrical portion may be electrically connected by being joined to a second current collector plate disposed at the axial second end of the electrode assembly.

[0062] The present invention provides a battery cell comprising the electrode assembly and a case housing the electrode assembly.

[0063] The above case may provide a first electrode terminal electrically connected to the first electrode, and a second electrode terminal electrically insulated from the first electrode terminal and electrically connected to the second electrode.

[0064] The above case may include a metal can and a terminal member installed through the can.

[0065] The first electrode terminal can be provided on the surface of a metal can.

[0066] The second electrode terminal can be provided to a terminal member installed through the can.

[0067] According to the present invention, the electrode is wound more at both ends than at the axial center of the electrode assembly at the outer circumferential end. Accordingly, a clearance is secured that allows the height-direction center of the electrode assembly to expand radially outward, thereby suppressing the rise in internal pressure of the electrode assembly while increasing energy density.

[0068] According to the present invention, while securing a clearance space that allows the central part of the electrode assembly in the height direction to expand radially outward, the gap with the side wall of the can at both ends in the height direction can be set narrowly, thereby increasing the fixation of the electrode assembly to the can and preventing the electrode assembly from vibrating or displaced within the can due to vibration or external impact.

[0069] According to the present invention, the dispersion of the roundness and cylindricality of the electrode assembly can be made uniform regardless of the behavior of the electrode assembly that changes as the charging and discharging of the battery cell is repeated, thereby suppressing the occurrence of defects.

[0070] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below.

[0071] FIG. 1 is an unfolded view of the first electrode, the first separator, the second electrode, and the second separator constituting the electrode assembly.

[0072] Figure 2 is a diagram showing the process of winding around a core with a separator interposed between the first electrode and the second electrode of Figure 1.

[0073] Figure 3 is a perspective view of an electrode assembly wound through the winding process of Figure 2.

[0074] FIG. 4 is a perspective view showing the state in which the electrode tab protruding from the axial end of the electrode assembly of FIG. 3 is flattened by bending it radially.

[0075] FIG. 5 is a perspective view showing the state in which a first current collector plate and a second current collector plate are joined to the axial first end and second end, respectively, of the electrode assembly of FIG. 4.

[0076] FIG. 6 is a perspective view of a cylindrical battery cell in which the electrode assembly of FIG. 5 is embedded in a case.

[0077] Figure 7 is a side cross-sectional view of the battery cell of Figure 6.

[0078] Figure 8 is a planar cross-sectional view of the battery cell of Figure 6.

[0079] FIG. 9 is an unfolded view of an electrode assembly of a first embodiment.

[0080] Figure 10 is an enlarged view of the outer circumferential end of the electrode of Figure 9.

[0081] FIG. 11 is an enlarged view of the outer circumference end of the electrode in the unfolded view of the electrode assembly of the second embodiment.

[0082] Figure 12 (a) is a perspective view of an electrode assembly of a second embodiment, and (b) is a perspective view of the electrode assembly of (a) with the separator omitted.

[0083] Figure 13 is a plan view of the electrode assembly of Figure 12.

[0084] FIG. 14 is an unfolded view of an electrode assembly of a third embodiment.

[0085] Fig. 15 is an enlarged view of the outer circumferential end of the electrode of Fig. 14.

[0086] [Explanation of the symbol]

[0087] 10: Can (Case) 11: Sidewall 111: Beading section 112: Crimping section 12: End wall 13: Terminal member 14: Gasket 16: Cap 17: Cap gasket 19: Insulator 20: Electrode assembly H: Height (Total height) D: Outer diameter 21: First electrode 22: Second electrode A: Center angle 23, 23-1, 23-2: Current collector 24, 24-1, 24-2: Active material 25, 25-1, 25-2: Retaining section 26, 26-1, 26-2: Non-retaining section 27, 27-1, 27-2: Electrode tab 28, 28-1, 28-2: Separator 29: Winding core hollow section dc: Central inner diameter de: End inner diameter 290: Winding shaft 30: First collector plate 31: Center 32: Edge 33: Arm 40: Second collector plate 41: First area 42: Second area 43: Bridge 51: Innermost end 52: Outermost end w, w1, w2: Width SS: Step section dL: Step distance dA: Step center angle 54: Connecting end 55: Horizontal section 56: Inclined section 561: Concave inclined section 562: Linear inclined section 563: Convex inclined section

[0088] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0089] Although terms such as "first," "second," etc., are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless specifically stated otherwise, the first component may also be the second component.

[0090] Throughout the specification, unless specifically stated otherwise, each component may be singular or plural.

[0091] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0092] In addition, where it is stated that one component is "connected," "combined," or "in contact" with another component, it should be understood that while the components may be directly connected or in contact with each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "in contact" through another component.

[0093] Singular expressions used in this specification include plural expressions unless the context clearly indicates otherwise. In this application, terms such as "composed of" or "comprising" should not be interpreted as necessarily including all of the various components or steps described in the specification, and should be interpreted as meaning that some of the components or steps may be omitted or additional components or steps may be included.

[0094] Throughout the specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise, and "C to D" means C or more and D or less unless specifically stated otherwise.

[0095] In describing the embodiments, the term "axial direction" refers to the direction in which the axis forming the winding center of the jelly-roll type electrode assembly extends, the term "radial direction" refers to the direction toward or toward the said axis, and the term "circumferential direction" refers to the direction surrounding the said axis.

[0096] The winding direction of the electrode or separator of the electrode assembly corresponds to the longitudinal direction of the electrode or separator. In addition, the axial direction of the electrode assembly is parallel to the width direction of the electrode or separator. One side or the other side of the axial direction corresponds to the upper side or the lower side of the electrode assembly when the cylindrical electrode assembly is in an upright position. The longitudinal core-side end or the winding-direction core-side end refers to the center-side end of the electrode assembly along the longitudinal direction of the electrode or separator, and the longitudinal outer-side end or the winding-direction outer-side end refers to the outer-side end of the electrode assembly along the longitudinal direction of the electrode or separator. One side or the other side end of the electrode or separator in the width direction corresponds to one side or the other side end of the electrode assembly in the axial direction.

[0097] A battery cell according to an embodiment of the present invention comprises an electrode assembly (20) and a case (10) that accommodates the electrode assembly (20).

[0098] The battery cell of the embodiment may be, for example, a cylindrical battery cell in which the ratio of the form factor (defined as the ratio of the diameter of the cylindrical battery cell to the height, i.e., the ratio of the diameter to the height) is approximately greater than 0.4.

[0099] Here, the form factor refers to a value representing the diameter and height of a cylindrical battery cell. The cylindrical battery cell may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, a 46800 cell, or a 46950 cell. In the numerical value representing the form factor, the first two digits represent the diameter of the cell, the next two digits represent the height of the cell, and the last digit 0 indicates that the cross-section of the cell is circular.

[0100] The battery cell may be a cylindrical battery cell that is approximately cylindrical in shape, with a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0101] A battery cell according to another embodiment may be a cylindrical battery cell having a roughly cylindrical shape, with a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0102] A battery cell according to another embodiment may be a cylindrical battery cell having a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.436.

[0103] A battery cell according to another embodiment may be a cylindrical battery cell having a roughly cylindrical shape, with a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0104] A battery cell according to another embodiment may be a cylindrical battery cell having a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0105] The present invention may, of course, be applied to battery cells having a form factor ratio of approximately 0.4 or less, such as 18650 cells, 21700 cells, etc. In the case of 18650 cells, the diameter is approximately 18 mm, the height is approximately 65 mm, and the form factor ratio is 0.277. In the case of 21700 cells, the diameter is approximately 21 mm, the height is approximately 70 mm, and the form factor ratio is 0.300.

[0106] In an embodiment, the axial height (H) of the electrode assembly (20) may be 70 mm to 110 mm, and the outer diameter (D) may be 40 mm to 48 mm.

[0107] Referring to FIGS. 1 to 4, the electrode assembly (20) is provided in the form of a jelly roll in which the first electrode (21) and the second electrode (22) are stacked so that a separator (28) is interposed, and the electrodes (21, 22) and the separator (28) are wound along their length. Accordingly, a separator (28) is interposed between the first electrode (21) and the second electrode (22).

[0108] Referring to FIG. 1, the electrodes (21, 22) and the separator (28) constituting the electrode assembly (20) of the embodiment may have the separator (28) being longer than the first electrode (21) in the longitudinal direction, the separator (28) being longer than the second electrode (22), and the first electrode (21) being longer than the second electrode (22).

[0109] Referring to FIG. 1 and FIG. 2, the electrode assembly (20) may be in a stacked form in the order of a second electrode (22), a first separator (28-1), a first electrode (21), and a second separator (28-2) in the stacking direction. That is, when viewed in the stacking order, the winding may be performed in a form in which the second electrode (22) is stacked closer to the core side than the first electrode (21).

[0110] A separator (28) may be placed at the core-side (Co) end of the electrode assembly (20) in the winding direction. That is, the longitudinal core-side ends of the first separator (28-1) and the second separator (28-2) begin to be wound while fixed to the winding pin (290), and subsequently, the first electrode (21) and the second electrode (22) begin to be wound. According to an embodiment, the first electrode (21) may begin to be wound before the second electrode (22) in the winding direction.

[0111] Referring to FIG. 1, in the winding direction of the electrode assembly (20), the core-side (Co) end of the separator (28) is positioned further towards the core than the core-side end of the first electrode (21), the core-side end of the separator (28) is positioned further towards the core than the core-side end of the second electrode (22), and the core-side end of the first electrode (21) is positioned further towards the core than the core-side end of the second electrode (22). Accordingly, in the radial direction, the first electrode (21) may be wound further inward than the second electrode (22).

[0112] In the winding direction of the electrode assembly (20), the outer circumferential (OP) end of the separator (28) is positioned further outward than the outer circumferential end of the first electrode (21), the outer circumferential end of the separator (28) is positioned further outward than the outer circumferential end of the second electrode (22), and the outer circumferential end of the first electrode (21) is positioned further outward than the outer circumferential end of the second electrode (22). Accordingly, at the outer circumferential end in the winding direction, the first electrode (21) may be extended further outward in the longitudinal direction than the second electrode (22). In other words, the second electrode (22) may not cover the outer circumferential end of the first electrode (21) in the winding direction from the radially outward side.

[0113] A separator (28) may be disposed on the innermost and outermost sides in the radial direction of the electrode assembly (20) wound in this manner.

[0114] In an embodiment, the first electrode (21) may be a negative electrode and the second electrode (22) may be a positive electrode. However, the present invention is not limited thereto. That is, it does not exclude the first electrode being a positive electrode and the second electrode being a negative electrode.

[0115] The first electrode (21) may be in the form in which a first active material (24-1) is coated on the surface of a first current collector (23-1). In an embodiment, the first current collector (23-1) may be a copper foil having a predetermined width and length. However, the present invention is not limited thereto.

[0116] The second electrode (22) may be in the form in which a second active material (24-2) is coated on the surface of a second current collector (23-2). In an embodiment, the second current collector (23-2) may be an aluminum foil having a predetermined width and length. However, the present invention is not limited thereto.

[0117] When considering a sheet-shaped electrode as a two-dimensional region, the two-dimensional region where an active material is coated on the surface of the current collector is referred to as the coated portion (25), and the region where an active material is not coated on the surface of the current collector is referred to as the uncoated portion (26). According to this, when considering a current collector (23) that has two sides in the form of a sheet, if an active material (24) is coated on either side of the current collector (23), that region can be referred to as the coated portion (25). On the other hand, if an active material (24) is not coated on both sides of the current collector (23), that region can be referred to as the uncoated portion (26).

[0118] The non-electric portion (26) of the above electrode may be provided for a function or operation other than a battery reaction. For example, the non-electric portion (26) may provide an electrode tab (27) that electrically connects the electrode to an electrode terminal. Specifically, the current collector (23) of the non-electric portion (26) itself may be utilized as the electrode tab (27), or a separate tab member may be attached to the current collector (23) of the non-electric portion (26) to provide the electrode tab.

[0119] For example, the above-mentioned non-removable portion (26) may be provided at least one of the core-side end and the outer-side end in the longitudinal direction of the electrode, that is, at the end of the winding direction of the jelly-roll electrode assembly (20), to alleviate the step difference in the thickness direction of the electrode and to alleviate the step difference in the radial direction of the electrode assembly (20).

[0120] In the winding direction of the electrode assembly (20), the core-side end of the first retaining part (25-1) of the first electrode (21) is positioned further towards the core than the core-side end of the second retaining part (25-2) of the second electrode (22), and the outer-side end of the first retaining part (25-1) is positioned further towards the outer-side than the outer-side end of the second retaining part (25-2).

[0121] According to an embodiment, the first electrode (21) is provided with a first uncoated portion (26-1) at the first end in the width direction, and the second electrode (22) is provided with a second uncoated portion (26-2) at the second end in the width direction. That is, at the first end in the width direction of the first electrode (21), a first current collector (23-1) that is not coated with a first active material (24-1) is exposed, and at the second end in the width direction of the second electrode (22), a second current collector (23-2) that is not coated with a second active material (24-2) is exposed.

[0122] Referring to FIGS. 1 and 3, the unoccupied portion (26) region protrudes outward in the widthwise or axial direction from the electrode laminate or jelly-roll. The unoccupied portion (26) itself functions as an electrode tab (27). In the widthwise or axial direction, the inner end of the unoccupied portion (26) is positioned further inward than the outer end of the separator (28), and the outer end of the unoccupied portion (26) is positioned further outward than the outer end of the separator (28).

[0123] In the above-mentioned blank portion (26), a cut line is formed at a predetermined interval, and a plurality of flag-shaped electrode tabs (27) arranged along the longitudinal direction can be provided.

[0124] The embodiment implements the electrode tabs (27) in the shape of an isosceles trapezoid. In addition to this, the shape of the electrode tabs (27) may be various shapes such as a semicircle, a semi-ellipse, a triangle, a rectangle, a parallelogram, etc.

[0125] An embodiment is exemplified in which the electrode tabs (27) arranged along the longitudinal direction have the same width (longitudinal dimension). However, the width of the electrode tabs may gradually or stepwise widen from the core side to the outer circumference side.

[0126] In addition, the embodiment illustrates a form in which the height (axial dimension) of the electrode tabs (27) increases stepwise from the core side to the outer side. However, the height of these electrode tabs (27) may also be implemented in a form that is constant or gradually decreases.

[0127] In addition, in the embodiment, a structure is exemplified in which the electrode tab (27) is removed from a predetermined section of the core-side end and a predetermined section of the centrifugal-side end of the non-core portion (26). However, it is obvious that the electrode tab may not be removed from the centrifugal-side end of the non-core portion, the electrode tab may not be removed from the centrifugal-side end of the non-core portion, or neither may be removed.

[0128] In the jelly roll-shaped electrode assembly (20), the electrode tab (27) is exposed axially outward as shown in FIG. 3 and can be flattened by being folded radially as shown in FIG. 4. The electrode tab (27) can be folded radially inward or outward. In an embodiment, a structure in which the electrode tab (27) is folded radially inward is exemplified.

[0129] The electrode tabs (27) can be folded one by one during the process of winding a laminate to form a jelly roll-shaped electrode assembly (20) as shown in FIG. 2. Alternatively, the electrode tabs (27) can be folded all at once and flattened as shown in FIG. 4 after winding a laminate to form a jelly roll-shaped electrode assembly as shown in FIG. 3.

[0130] The first electrode tabs (27-1) of the first electrode (21) and the second electrode tabs (27-2) of the second electrode (22), which are folded and overlapped in the radial direction, can each provide a first surface and a second surface that are substantially perpendicular to the axial direction at both axial ends of the electrode assembly (20).

[0131] As shown in FIG. 5, a first current collector plate (30) and a second current collector plate (40) can be joined to the substantially flat first surface and second surface, respectively, provided by bending the electrode tabs (27) that are exposed at each axial end of the electrode assembly (20).

[0132] One of the first current collector plate (30) and the second current collector plate (40) may be a positive current collector plate and the other may be a negative current collector plate. In an embodiment, the first current collector plate (30) is a negative current collector plate and the second current collector plate (40) is a positive current collector plate.

[0133] The first current collector plate (30) and the second current collector plate (40) may include copper or aluminum materials. An embodiment is implemented such that the first current collector plate (30) includes copper material and the second current collector plate (40) includes aluminum material.

[0134] The above current collector plates (30, 40) can be manufactured by punching, trimming, piercing, or bending a metal sheet or a metal plate.

[0135] Referring to FIG. 5, the second current collector plate (40) includes a first region (41) provided in a portion corresponding to the core hollow (29) of the electrode assembly (20), and a second region (42) provided around the first region (41). The first region (41) is positioned at the center of the second current collector plate (40) and is provided in a form that covers at least a portion of the core hollow (29) of the electrode assembly (20) in the axial direction. The second region (42) is provided in a form that surrounds the first region (41) while being spaced radially apart from the first region (41).

[0136] The first region (41) and the second region (42) are physically and electrically connected to each other through a bridge (43). The bridge (43) extends radially, is connected to the first region (41) on the inner side of the radial direction, and is connected to the second region (42) on the outer side of the radial direction.

[0137] In an embodiment, the bridge portion (43) may be radially extended with respect to the first region (41) and arranged in multiple numbers in the circumferential direction. The bridge portion (43) may have a radial extension length that is longer than the circumferential width.

[0138] The second region (42) can be electrically connected by being joined to a second electrode tab (27-2) provided on the second electrode (22) of the electrode assembly (20). The first region (41) can be electrically connected by being joined to a terminal member (13) to be described later.

[0139] Referring to FIGS. 5 and FIGS. 7, the first collector plate (30) comprises a central portion (31) including a ring-shaped portion having a hole formed in the center. The central portion (31) may further include an extension portion extending radially outward from the ring-shaped portion. A plurality of extension portions may be spaced apart in the circumferential direction.

[0140] The first collector plate (30) has an edge portion (32) that surrounds the central portion (31) on the radial outer side of the central portion (31). The central portion (31) and the edge portion (32) may be spaced apart in the radial direction and also spaced apart in the axial direction.

[0141] The first collector plate (30) above is provided with an arm portion (33) connecting the central portion (31) and the edge portion (32). The arm portion (33) is extended obliquely in the axial and radial directions and can be spaced apart in multiple places along the circumferential direction. The arm portion (33) can be arranged between the extension portions in the circumferential direction.

[0142] The central portion (31) may be electrically connected by being joined to a first electrode tab (27-1) provided on the first electrode (21) of the electrode assembly (20). The edge portion (32) may be electrically connected by being joined to at least one of the side wall (11) and the cap (16) of the case (10) to be described later. An embodiment illustrates that the edge portion (32) is joined to the side wall (11).

[0143] Referring to FIGS. 6 and FIGS. 7, the electrode assembly (20) can be inserted into a case (10) with the first current collector plate (30) and the second current collector plate (40) joined together as shown in FIG. 5.

[0144] The above case (10) may include a metal can. The can (10) includes a side wall (11) extending axially between a first end and a second end, and an end wall (12) connected to the second end of the side wall (11) and extending radially. The end wall (12) may form a flat disc shape intersecting the axial direction, and the side wall (11) may be a circular tube shape extending along the axial direction.

[0145] The above end wall (12) and side wall (11) can be manufactured by forming a metal sheet, on which nickel is plated on the surface of steel, using a deep drawing process, and then trimming the first end of the side wall (11) with a punch while holding it with a blank holder. Of course, the material and manufacturing method of the can (10) are not limited to this.

[0146] A hole is provided in the center of the end wall (12), and a terminal member (13) can be fitted into the hole. The terminal member (13) can be fixed to the end wall (12) by plastic processing such as caulking or riveting with a gasket (14) interposed therebetween. The gasket (14) is interposed between the terminal member (13) and the end wall (12) to seal the inside and outside with respect to the end wall (12) to prevent leakage of the electrolyte and to electrically insulate the terminal member (13) and the end wall (12) from each other.

[0147] However, the method of connecting the terminal member (13) and the can (10) is not limited to this. For instance, if the structure can seal the space between the terminal member (13) and the can (10) and electrically insulate the terminal member (13) and the can (10), various other fixing methods other than this plastic processing, such as a bolt-nut connection method, a glass seal method, or a method of heat-bonding PP-MAH to the chrome coating on the surface of the can, can also be applied.

[0148] The first end of the above side wall (11) is open to define the opening of the can (10).

[0149] The electrode assembly (20) is received in the can (10) with the second current collector plate (40) aligned toward the end wall (12) of the can (10). An insulator (19) is interposed between the second current collector plate (40) and the end wall (12) to electrically insulate the second current collector plate (40) and the end wall (12) from each other.

[0150] The first region (41) of the second current collector plate (40) can be electrically connected to and fixed to the terminal member (13). For example, the terminal member (13) fixed to the can (10) can be fixed and electrically connected by being joined to the surface of the first region (41) of the second current collector plate (40) by a welding method such as welding. The terminal member (13) of the can (10) and the first region (41) can be connected after the electrode assembly (20) is placed in the can (10).

[0151] Accordingly, the terminal member (13) may have a polarity corresponding to the second electrode (22). For example, the polarity may be positive. The surface of the head portion of the terminal member may form an electrode terminal, specifically a positive terminal.

[0152] The edge portion (32) of the first current collector plate (30) can be electrically connected by being joined to the vicinity of the first axial end of the side wall (11). Specifically, the vicinity of the first axial end of the side wall (11) is plastically processed to be recessed radially inward to form a beading portion (111), and the edge portion (32) of the first current collector plate (30) is joined to the surface of the beading portion (111). Accordingly, the side wall (11) can have a polarity corresponding to the first electrode (21). For example, the polarity may be a negative electrode.

[0153] The end wall (12) is electrically connected to the side wall (11). Therefore, the end wall (12) can also have a polarity corresponding to the first electrode (21). The diameter of the head portion of the terminal member (13) disposed on the outer side of the end wall (12) may be about 1 / 3 of the diameter of the end wall (12). That is, the surface of the end wall (12) may have a sufficient area for the bus bar to be joined. Accordingly, the end wall (12) can form an electrode terminal, specifically a negative terminal.

[0154] An electrode assembly (20) is housed in the can (10), and the first current collector plate (30) and the second current collector plate (40) are electrically connected to the electrode terminals, respectively. After injecting an electrolyte into the can (10), the opening of the can (10) can be sealed by covering it with a lid or a cap (16). The outer perimeter of the cap (16) in the radial direction can be sealed and fixed to the first axial end of the side wall (11).

[0155] The edge of the cap (16) is placed on the beading portion (111) with the cap gasket (17) interposed therein. Then, the edge of the cap (16) is sealed and fixed by compressing it with a crimping portion (112) formed by plastically processing the axial first end of the side wall (11) inwardly in a radial direction, such as by caulking or bending.

[0156] According to an embodiment, both the first electrode terminal and the second electrode terminal may be disposed at the axial second end of the battery cell. Accordingly, the busbar connected to the terminal member (13) of the battery cell and the busbar connected to the end wall (12) may both be located at the top of the battery cell.

[0157] Referring to FIG. 7, the electrode assembly (20) of the embodiment may be a cylindrical jelly-roll structure having a predetermined inner diameter, outer diameter (D), and height (H). The inner diameter refers to the inner diameter of the core hollow portion (29) of the electrode assembly (20). The inner diameter may be measured as a central inner diameter (dc) measured at the center of the height direction of the electrode assembly (20) and an end inner diameter (de) measured at the end of the height direction, specifically at the first end in the axial direction. Meanwhile, referring to FIG. 8, the electrode assembly (20) has a central angle (A) defined as the angle between the position of the core-side end of the electrode in the winding direction and the position of the outer-side end in the circumferential direction.

[0158] It is known that as the battery cell is repeatedly charged and discharged, the electrode assembly (20) undergoes repeated expansion and contraction. In the embodiment, to quantitatively track the behavior of the expansion and contraction of the electrode assembly (20), the battery cell is repeatedly charged and discharged, and the changes in the inner diameter, outer diameter (D), and central angle (A) are measured.

[0159] As the charging and discharging of the activated battery cell are repeated, the inner diameter and outer diameter (D) change, and the central angle (A) also changes. Meanwhile, although the central angle (A) itself may differ between the central angle (A) of the first electrode (21) and the central angle (A) of the second electrode (22), for tracking the behavior of the electrode assembly (20), the change in the central angle (A) rather than the central angle (A) itself is more meaningful information, and the amount of change in the central angle (A) itself does not differ significantly between the first electrode (21) and the second electrode (22). Accordingly, in the embodiment, the central angle (A) of the first electrode (21) was measured.

[0160] In the initial state before repeating the charging and discharging of the activated battery cell, the outer diameter (D) of the electrode assembly (20) is approximately 46 mm, and the inner diameter is approximately 6.3 mm.

[0161] Charge and discharge experiments were performed on 6 activated battery cell samples.

[0162] First, two samples were selected for each of the three groups according to the cylindrical level of the electrode assembly (20) of the activated battery cell.

[0163] For each sample, charging and discharging were repeated, with each charge and discharge being fully charged to C / 2 and then fully discharged to C / 2. The external dimensions of the battery cells were measured by CT scanning before the charge and discharge repetition, after 5 charge and discharge cycles, and after 15 charge and discharge cycles at a state of charge (SOC) of 30%.

[0164] Group Sample Period Dmin(mm) D(mm) Dmax(mm) Dmax-Dmin Cylindricity 11 Initial 45.9 11 45.9 9 146.1 2 20.2 1 10.1 8 25 times After 45.9 3 46.0 14 46.1 3 20.2 20.1 66 15 times After 45.9 26 45.9 9 3 46.0 8 90.1 6 3 0.1 5 3 2 Initial 45.8 65 45.9 7 146.1 0 30.2 3 80.1 7 8 times After 45.8 89 45.9 76 46.0 9 90.2 1 0.1 86 15 times After 45.9 6 46.0 26 46.1 2 6 0.1 66 0.1 1 2 3 Initial 45.9 0 7 45.9 9 246.0 7 70.1 7 0.1 45 times After 45.924 45.983 46.055 0.13 10.153 15 times After 45.965 46.037 46.093 0.128 0.1164 Initial 45.943 46.007 46.096 0.153 0.145 5 times After 45.947 46.002 46.073 0.126 0.125 15 times After 45.956 46.002 46.067 0.11 10.11435 Initial 45.965 46.004 46.048 0.083 0.08 35 times After 45.957 46.003 46.041 0.084 0.094 15 times After 45.98 46.007 46.038 0.058 0.0556 Initial 45.94446 46.045 0.10 10.08 5 times After 45.973 46.018 46.05 40.08 10.099 15 times After 45.981 46.006 46.027 0.046 0.048

[0165] Upon examination, it can be confirmed that as charging and discharging are repeated, the minimum outer diameter (Dmin) gradually increases and the maximum outer diameter (Dmax) gradually decreases, while the average outer diameter (D) remains unchanged and the difference between the maximum and minimum outer diameters (Dmax-Dmin) gradually decreases, indicating an improvement in cylindricality. Similarly, the cylindricality of the samples also improved as charging and discharging were repeated.

[0166] In addition, the change in the central angle (A) of samples 1 to 6 was measured, and the change in the central angle (A) of group 1 and group 2 is as follows.

[0167] Group Initial (A) After 5 times (A) After 15 times (A) 127°C 37°C 40°C 240°C -60°C

[0168] Upon examination, the central angle (A) of all samples in each group showed a gradual increase as charging and discharging were repeated.

[0169] When reviewing the experimental results in Tables 1 and 2 above, it can be seen that the degree of the central angle (A) and the degree of cylindricity have a significant relationship, and that as charging and discharging progress, the central angle (A) increases and the degree of cylindricity improves. However, the degree and timing of the central angle (A) increasing as charging and discharging are repeated are irregular.

[0170] In addition, as can be seen from the samples above, even if the same parts (21, 22, 28) are fed into the same manufacturing equipment (winding device) to produce an electrode assembly (20), the average outer diameter of the electrode assembly (20) is uniform, but it is very difficult to regulate the central angle (A) of the core-side end and the outer-side end of the electrode of the electrode assembly (20), and it is also difficult to predict the behavior of the change in the central angle (A) as charging and discharging are repeated.

[0171] Meanwhile, the inner diameters of the samples measured in the initial state before charging and discharging, and the inner diameters of the samples after 15 charge-discharge cycles are as follows.

[0172] Period dc (mm) de (mm) Initial 6.33 6.3415 times After 6.47 6.78

[0173] Upon examination, it can be seen that there is almost no difference between the inner diameter of the center (dc) and the inner diameter of the end (de) before repeated charging and discharging, but after repeated charging and discharging, the inner diameter of the center (dc) has decreased even more than the inner diameter of the end (de). In other words, the difference in inner diameter between the center and the end, which was 0.01 mm, became 0.31 mm after 15 repeated charging and discharging cycles.

[0174] In addition, to check the pressure applied inside the electrode assembly (20) as charging and discharging are repeated, an experiment was conducted in which charging and discharging were repeated 15 times with different charging voltages, and after the experiment, the phenomenon of the negative active material being detached to the separator in contact with it was observed as follows.

[0175] Position (Radical) Position (Height) Initial 4.25V Repeat 4.3V Repeat Core Side 1st Stage No detachment No detachment No detachment Center No detachment No detachment No detachment 2nd Stage No detachment No detachment No detachment Intermediate Section 1st Stage No detachment No detachment No detachment Center No detachment No detachment Severe detachment 2nd Stage No detachment No detachment No detachment Outer perimeter Side 1st Stage No detachment No detachment No detachment Center No detachment No detachment Slight detachment 2nd Stage No detachment No detachment No detachment

[0176] Upon examination, it was confirmed that delamination occurs when charging and discharging are repeated at voltages exceeding a certain level, and that this delamination occurs in the central part of the electrode assembly in the height direction. Furthermore, while delamination does not occur on the radial core side of the electrode assembly, it occurs slightly on the radial outer periphery and is more pronounced in the radial middle section.

[0177] From this, it can be confirmed that when the charging and discharging of a cylindrical battery cell are repeated above a specific voltage, a greater pressure is applied to the central part of the electrode assembly than to both ends in the height direction, and also that a greater pressure is applied to the middle section than to the radial core side and outer circumference side of the electrode assembly.

[0178] When reviewing the experimental results of Tables 3 and 4 above, it can be confirmed that when charging and discharging are performed at high voltage, the highest internal pressure is applied to the radial middle section of the center in the height direction of the electrode assembly as the charging and discharging are repeated, followed by the internal pressure applied to the radial outer side of the center in the height direction of the electrode assembly.

[0179] In addition, similar results were obtained even when rapid charging and discharging was performed at 1C (25Ah).

[0180] That is, when the electrode assembly (20) is to expand due to gas generated during the charging and discharging process, the core side of the electrode assembly (20) has a hollow core (29) so that no large internal pressure is applied, and both ends of the electrode assembly (20) in the height direction (axial direction) are in communication with the internal space of the can (10) so that the gas can be discharged well, whereas the radial middle section of the center of the electrode assembly (20) in the height direction has no space to expand freely so that the highest internal pressure is generated, and the radial outer side of the center of the electrode assembly (20) in the height direction has a slight gap with the inner surface of the side wall (11) of the can (10) so that there is room to expand in the radial direction, so it can be estimated that a slightly lower internal pressure is applied.

[0181] From these factors, it can be concluded that if the radial outer side of the central part in the height direction of the electrode assembly (20) has a sufficient gap with the inner surface of the side wall (11) of the can (10), the internal pressure of the radial outer side of the central part in the height direction of the electrode assembly (20) as well as the internal pressure of the radial middle section can be suppressed from rising.

[0182] It can be seen that when charging with high voltage or high-speed charging, the internal pressure of the electrode assembly (20) increases significantly. However, electric vehicles cannot avoid an environment where high-speed discharge occurs for high output, and cannot avoid an environment where high-speed charging occurs for fast charging.

[0183] In addition, even if the electrode assembly (20) is produced in the same facility, it is not possible to avoid variations in the initial roundness and cylindricity due to variations in the central angle (A) of both ends of the electrode in the longitudinal direction, and the behavior of these changes during the charging and discharging process cannot be uniformly predicted.

[0184] In order to absorb deviations in the roundness and cylindricity of the electrode assembly (20) and to secure a margin of space for the electrode assembly (20) to expand radially outward, a method of setting a large gap between the side wall (11) of the can (10) of the cylindrical battery cell and the outer surface of the electrode assembly (20) may be considered. Then, it is expected that the internal pressure generation of the electrode assembly (20) can be suppressed despite the dispersion of the roundness and cylindricity of the electrode assembly (20).

[0185] However, this causes a decrease in the energy density of the battery cell. In addition, this causes the amplitude of the relative vibration between the can (10) and the electrode assembly (20) to increase due to vibrations or shocks occurring during the operation of the electric vehicle, which can shorten the lifespan of the battery cell.

[0186] The embodiment provides an electrode assembly (20) that minimizes the gap between the battery cell can (10) and the electrode assembly (20) despite deviations in the roundness and cylindricality of the electrode assembly (20), while not reducing the energy density of the battery cell, suppresses relative vibration between the can (10) and the electrode assembly (20), and suppresses the generation of internal pressure in a high-speed charging / discharging or high-voltage charging / discharging environment.

[0187] FIGS. 9 and 10 illustrate a first embodiment, FIGS. 11 to 13 illustrate a second embodiment, and FIGS. 14 and 15 illustrate a third embodiment.

[0188] For convenience of explanation, embodiments of the present invention are described under the premise that the width direction of the electrode corresponds to or is parallel to the axial direction of the electrode assembly, the axial direction of the electrode assembly corresponds to the height direction of the electrode assembly, and the length direction of the electrode corresponds to the circumferential direction of the electrode assembly.

[0189] Referring to FIGS. 9 to 15, in an embodiment, the electrode assembly (20) is such that at least one of the first electrode (21) and the second electrode (22) has its outer circumferential (OP) end in the longitudinal direction extended further along the longitudinal direction than the central part in the width direction of the electrode intersecting the longitudinal direction. The first and second embodiments are implemented such that the first electrode (21) is as described above, and the third embodiment is implemented such that both the first electrode (21) and the second electrode (22) are as described above.

[0190] The longitudinal outer end of at least one electrode comprises an innermost end (51) disposed at the center of the width direction of the electrode and provided at the innermost end in the longitudinal direction, and a pair of outermost ends (52) disposed at both ends of the width direction of the electrode and provided at the outermost end in the longitudinal direction.

[0191] And, the outer end of the electrode having the innermost end (51) and a pair of outermost ends (52) further has a pair of connecting ends (54) that connect the innermost end (51) and the pair of outermost ends (52) respectively.

[0192] The widthwise lengths (w1, w2) of each of the pair of outermost ends (52) of the outer circumferential end of the electrode, measured in the axial direction of the electrode assembly (20), may correspond to each other or differ from each other. An embodiment is implemented such that the first width (w1) and the second width (w2) of the outermost end (52) differ from each other.

[0193] Preferably, the widthwise lengths (w1, w2) of each outermost end (52) may be 0.1 or more and 0.3 or less relative to the axial length (H) of the electrode assembly (20). If the ratio is less than 0.1, the fixing force of the electrode assembly (20) to the can (10) is insufficient and the energy density deteriorates. Additionally, if the ratio exceeds 0.3, it is difficult to sufficiently secure a gap between the central region of the electrode assembly (20) in the height direction and the can (10).

[0194] According to the embodiment, the outer circumferential (OP) end of the first electrode (21) is generally finished with a first retaining portion (25-1), and the axial first end is finished with a first non-retaining portion (26-1). And the outer circumferential (OP) end of the second electrode (22) is generally finished with a second retaining portion (25-2), and the axial second end is finished with a second non-retaining portion (26-2).

[0195] In order to appropriately set the positive / negative loading ratio (N / P ratio), the height of the first retaining portion (25-1) of the first electrode (21) may be set higher than the height of the second retaining portion (25-2) of the second electrode (22). Accordingly, the height of the second non-retaining portion (26-2) may be set higher than the height of the first non-retaining portion (26-1).

[0196] In the first embodiment, the widths of the first retaining portion (25-1) present at a pair of outermost ends (52) of the first electrode (21) are different from each other, and a first non-retaining portion (26-1) is further present at one outermost end (52), so that the first width (w1) is shorter than the second width (w2). On the other hand, the outer circumferential (OP) end of the second electrode (22) is implemented in a form that extends substantially parallel to the axial direction of the electrode assembly (20).

[0197] In the second embodiment, the widths of the first retaining portions (25-1) present at the pair of outermost ends (52) of the first electrode (21) correspond to each other, but a first non-retaining portion (26-1) is additionally present at one outermost end (52), so that the first width (w1) is implemented to be shorter than the second width (w2). On the other hand, the outer circumferential (OP) end of the second electrode (22) is implemented in a form that extends substantially parallel to the axial direction of the electrode assembly (20).

[0198] According to the first and second embodiments, the innermost end (51) of the outer end of the first electrode (21) is positioned further outward than the outer end of the second electrode (22).

[0199] In the third embodiment, the widths of the first retaining portions (25-1) present at the pair of outermost ends (52) of the first electrode (21) correspond to each other, but a first non-retaining portion (26-1) is additionally present at one outermost end (52), so that the first width (w1) is implemented to be shorter than the second width (w2). Similarly, the widths of the second retaining portions (25-2) present at the pair of outermost ends (52) of the second electrode (22) also correspond to each other, but a second non-retaining portion (26-2) is additionally present at the other outermost end (52), so that the first width (w1) is implemented to be longer than the second width (w2).

[0200] According to the third embodiment, the innermost end (51) and the outermost end (52) of the outer circumferential end of the first electrode (21) are positioned further outward than the innermost end (51) and the outermost end (52) of the second electrode (22), respectively. Also, according to the third embodiment, the connecting end (54) of the outer circumferential end of the first electrode (21) is positioned further outward than the connecting end (54) of the second electrode (22).

[0201] Meanwhile, the connecting end (54) may have at least one of a horizontal section (55) that extends parallel to the longitudinal direction as it extends outward in the longitudinal direction of the electrode, and an inclined section (56) that extends obliquely toward the outer side in the width direction of the electrode as it extends outward in the longitudinal direction of the electrode.

[0202] Each slope section (56) may include at least one of a concave slope section (561) in which the degree of extension to the width direction outward gradually decreases as it extends outward in the length direction, a linear slope section (562) in which it extends uniformly outward in the width direction, and a convex slope section (563) in which the degree of extension to the width direction outward gradually increases.

[0203] That is, one slope section (56) may include a linear slope section (562), a concave slope section (561), a convex slope section (563), a linear slope section (562) and a concave slope section (561), a linear slope section (562) and a convex slope section (563), a concave slope section (561) and a convex slope section (563), or a concave slope section (561), a linear slope section (562), and a convex slope section (563).

[0204] The above connecting end (54) may have one or more horizontal sections (55), one or more inclined sections (56), or one or more horizontal sections (55) and one or more inclined sections (56).

[0205] The first embodiment is implemented in a form in which the connecting end (54) comprises a horizontal section (55) and a pair of inclined sections (56) each connected to both sides in the longitudinal direction of the horizontal section (55). The first embodiment is implemented in such a form in which the inclined sections (56), each positioned on the inner and outer sides of the horizontal section (55) in the longitudinal direction of the first electrode (21), each include a concave inclined section (561) and a convex inclined section (563).

[0206] The second and third embodiments are implemented such that the connecting end (54) has a single slope section (56). The second embodiment is implemented such that the slope section (56) has a linear slope section (562). The third embodiment is implemented such that the slope section (56) has a concave slope section (561).

[0207] The innermost end (51) of the outer circumferential end of the electrode may be implemented in a straight line extending in a direction parallel to the axial direction of the electrode assembly (20), or may be implemented in a form where a pair of connecting ends (54) are directly connected without the straight line.

[0208] The first and second embodiments can be implemented in a form in which the innermost end (51) is extended straight so as to be parallel to the axial direction of the electrode assembly (20).

[0209] In contrast, the third embodiment is implemented in such a way that the part where a pair of connecting ends (54) are connected constitutes the outermost end (52).

[0210] In one example, the connecting end (54) may have a concave slope section (561) and a linear slope section (562). The linear slope section (562) may be positioned further outward in the longitudinal direction than the concave slope section (561). The concave slope section (561) and the linear slope section (562) may be directly connected or connected with another section interposed between them.

[0211] In another example, the connecting end (54) may include the concave slope section (561) and the convex slope section (563). The convex slope section (563) may be positioned further outward in the longitudinal direction than the concave slope section (561). The concave slope section (561) and the convex slope section (563) may be directly connected or connected with another section interposed between them.

[0212] The first embodiment is implemented in such a way that the connecting end (54) provided at the outer end of the first electrode (21) includes a concave slope section (561) and a convex slope section (563), and the concave slope section (561) and the convex slope section (563) are connected with a horizontal section (55) interposed therebetween.

[0213] In another example, the connecting end (54) may include the linear slope section (562) and the convex slope section (563). The convex slope section (563) may be positioned further outward in the longitudinal direction than the linear slope section (562). The linear slope section (562) and the convex slope section (563) may be directly connected or connected with another section interposed between them.

[0214] In the longitudinal direction of the electrode, the section between the innermost end (51) and the outermost end (52) defines a step section (SS). The step distance (dL) refers to the length of the step section (SS) measured along the longitudinal direction of the electrode. The step center angle (dA) refers to the size of the center angle occupied by the step section (SS) with respect to the center of the jelly-roll shaped electrode assembly (20).

[0215] Referring to FIGS. 12 and 13, in the electrode assembly (20) of the embodiment, the axial central region of the electrode corresponding to the stepped section (SS) is cut out at the radial outer circumference of the electrode assembly (20). Accordingly, at the stepped section (SS), an existing region where the electrode portion exists is provided at both axial ends of the electrode assembly (20), while an non-existent region where the electrode portion does not exist is provided at the axial central region.

[0216] Therefore, since the gap between the electrode assembly (20) and the side wall (11) of the can (10) is defined by the existing region, the gap between the can (10) and the electrode assembly (20) can be minimized. Accordingly, relative vibration between the can (10) and the electrode assembly (20) can be suppressed, and the energy density is not reduced.

[0217] In contrast, in the above-mentioned non-existent region, a sufficient gap can be secured between the can (10) and the electrode assembly (20). Accordingly, the gas generated during the charging and discharging process of the battery cell is delayed in discharge at the height-direction center of the electrode assembly (20), and when the electrode assembly (20) expands radially, the expansion of the electrode assembly (20) is further allowed, thereby suppressing the rise in internal pressure generated at the height-direction center of the electrode assembly (20).

[0218] Additionally, since an innermost end (51), an outermost end (52), and a connecting end (54) connecting them are provided at the outer end of at least one of the pair of electrodes (21, 22), the azimuth position of the outer end of the electrode relative to the center of the electrode assembly (20) varies along the height direction of the electrode assembly (20). That is, the circumferential position where the maximum outer diameter of the electrode assembly (20) exists varies according to the height direction position of the electrode assembly (20).

[0219] On the other hand, in an electrode assembly (20) in which the outer end of the electrode is finished in a form that extends straight in the axial direction, at a circumferential position where the maximum outer diameter of the electrode assembly (20) exists, the maximum outer diameter portion is located throughout the entire height direction of the electrode assembly (20).

[0220] Accordingly, as the charging and discharging process of the battery cell is repeated, the electrodes (21, 22) of the electrode assembly (20) of the embodiment expand in the longitudinal direction, causing the central angle (A) between the core side (Co) end and the outer side (OP) end of the electrodes (21, 22) to change. Even if it is difficult to predict the change, even if the circumferential position of the maximum outer diameter of the electrode assembly (20) overlaps with the core side end of the electrode in the radial direction, causing an area that worsens the cylindricity and roundness, this exists only in a localized area in the height direction of the electrode assembly (20). Therefore, the production dispersion of the roundness and cylindricity of the electrode assembly (20) can be made uniform.

[0221] Preferably, the center angle (dA) of the step difference between the innermost end (51) and the outermost end (52) of the electrode with respect to the center of the electrode assembly (20) may be 30 degrees or more and 720 degrees or less. That is, the number of turns in which the connecting end (54) of the outer circumference end of the electrode surrounds the electrode assembly (20) may be 1 / 12 times or more and 2 times or less.

[0222] If the above step center angle (dA) is less than 30 degrees, it is difficult to achieve uniform production distribution regarding roundness and cylindricity even if the step section (SS) is implemented between the innermost end (51) and the outermost end (52). In addition, if the above step center angle (dA) exceeds 720 degrees, the gap between the electrode assembly (20) and the side wall (11) of the can (10) at the height center of the electrode assembly (20) becomes larger than necessary, and there is a risk that the energy density will decrease.

[0223] Preferably, in the longitudinal direction of the electrode, the step distance (dL) between the innermost end (51) and the outermost end (52) may be 20 mm or more and 480 mm or less. That is, the distance at which the connecting end (54) of the outer circumferential end of the electrode extends along the longitudinal direction of the electrode may be 20 mm or more and 480 mm or less.

[0224] If the above step distance (dL) is less than 20 mm, it is difficult to achieve uniform production distribution regarding roundness and cylindricity even if a step section (SS) is implemented between the innermost end (51) and the outermost end (52). Additionally, if the above step distance (dL) exceeds 480 mm, the gap between the electrode assembly (20) and the side wall (11) of the can (10) at the height-direction center of the electrode assembly (20) becomes larger than necessary, and there is a risk that the energy density will decrease.

[0225] Preferably, the first and second embodiments, in which the outermost end (52) and the innermost end (51) are provided at the longitudinal outer end of the first electrode (21), are implemented in such a way that the center angle of the step (dA) is 30 degrees or more and 60 degrees or less. Preferably, the step distance (dL) may be 20 mm or more and 40 mm or less.

[0226] According to this embodiment, among the first effect of further securing a gap between the height-direction center of the electrode assembly (20) and the side wall (11) of the can (10) and the second effect of evenly dispersing the roundness and cylindricality of the electrode assembly (20), the second effect can be further expressed.

[0227] Preferably, the third embodiment, in which the outermost end (52) and the innermost end (51) are provided at the longitudinal outer circumference ends of the first electrode (21) and the second electrode (22), is implemented in a form in which the center angle of the step (dA) is 60 degrees or more and 360 degrees or less. Preferably, the step distance (dL) may be 40 mm or more and 240 mm or less.

[0228] According to this embodiment, the first effect among the first effect and the second effect can be further expressed.

[0229] It goes without saying that the details applied to the embodiments described above may be mutually substituted, modified, or omitted to the extent that the intent of the invention is not compromised.

[0230] The embodiments described above should be understood as exemplary in all respects and not limiting, and the scope of the invention will be defined by the claims set forth below rather than by the detailed description above. Furthermore, the meaning and scope of the claims set forth below, as well as all modifications and variations derived from equivalents thereof, should be interpreted as being included within the scope of the invention.

[0231] Although the present invention has been described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration according to the present invention were not explicitly described while describing the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized.

Claims

1. A jelly-roll type electrode assembly in which a first electrode and a second electrode are wound around a core axis along the longitudinal direction with a separator in between, An electrode assembly in which the outer circumferential end of at least one of the first electrode and the second electrode is further extended outward along the longitudinal direction than the central part of the electrode in the width direction intersecting the longitudinal direction.

2. The electrode assembly of claim 1, wherein the electrode assembly is in the form of a cylindrical jelly-roll wound around a circular core shaft.

3. In claim 1, the first electrode is longer than the second electrode in the longitudinal direction, and The outer end portion of the first electrode is an electrode assembly in which both ends in the width direction are extended further outward along the length direction than the central portion in the width direction.

4. The electrode assembly of claim 3, wherein the outer circumferential end of the second electrode extends substantially parallel to the axial direction of the electrode assembly.

5. An electrode assembly according to claim 1, wherein the outer circumferential ends of each of the first electrode and the second electrode are extended further along the longitudinal direction toward the outer circumferential side than the central part of the electrode in the width direction intersecting the longitudinal direction.

6. An electrode assembly according to claim 1, wherein, in the longitudinal direction of the electrode, the step distance between the innermost end provided at the center of the width direction of the electrode and the outermost end provided at both ends of the width direction of the electrode is 20 mm or more and 480 mm or less.

7. An electrode assembly according to claim 6, wherein the step distance is 40 mm or more.

8. An electrode assembly according to claim 6, wherein the step distance is 240 mm or less.

9. An electrode assembly according to claim 8, wherein the step distance is 40 mm or less.

10. An electrode assembly according to claim 1, wherein, in the longitudinal direction of the electrode, the step section between the innermost end provided at the center of the width direction of the electrode and the outermost end provided at both ends of the width direction of the electrode has a step center angle surrounding the electrode assembly of 30 degrees or more and 720 degrees or less.

11. An electrode assembly according to claim 10, wherein the center angle of the step is 60 degrees or more.

12. An electrode assembly according to claim 10, wherein the center angle of the step is 360 degrees or less.

13. An electrode assembly according to claim 12, wherein the center angle of the step is 60 degrees or less.

14. An electrode assembly according to claim 1, wherein the axial lengths of the outermost ends provided at each end in the width direction of the electrode are different from the height of the electrode assembly measured in the axial direction.

15. An electrode assembly according to claim 1, wherein the axial lengths of the outermost ends provided at each end in the width direction of the electrode correspond to each other relative to the height of the electrode assembly measured in the axial direction.

16. An electrode assembly according to claim 1, wherein the axial length of the outermost end provided at each end in the width direction of the electrode relative to the height of the electrode assembly measured in the axial direction is 0.1 or more and 0.3 or less.

17. An electrode assembly according to claim 1, wherein the connecting end connecting the innermost end provided in the center of the width direction of the electrode and the outermost end provided at both ends of the width direction of the electrode comprises at least one of a horizontal section extending parallel to the length direction as it extends outward in the length direction of the electrode and an inclined section extending obliquely toward the outer side of the width direction of the electrode as it extends outward in the length direction of the electrode.

18. An electrode assembly according to claim 17, wherein the inclined section comprises a concave inclined section in which the degree of extension in the width direction gradually decreases as it extends outward in the longitudinal direction.

19. An electrode assembly according to claim 17, wherein the inclined section comprises a linear inclined section that extends uniformly outward in the width direction as it extends outward in the longitudinal direction.

20. An electrode assembly according to claim 17, wherein the inclined section comprises a convex inclined section in which the degree of extension in the width direction outward gradually increases as it extends outward in the longitudinal direction.

21. In claim 18, the slope section further comprises a linear slope section that extends uniformly outward in the width direction as it extends outward in the longitudinal direction, and The above linear slope section is positioned further outward in the longitudinal direction than the above concave slope section, in an electrode assembly.

22. In claim 18, the inclined section further comprises a convex inclined section in which the degree of extension in the width direction outward gradually increases as it extends outward in the longitudinal direction, and The electrode assembly, wherein the convex slope section is positioned further outward in the longitudinal direction than the concave slope section.

23. In claim 19, the inclined section further comprises a convex inclined section in which the degree of extension in the width direction outward gradually increases as it extends outward in the longitudinal direction, and The above convex slope section is positioned further outward in the longitudinal direction than the above linear slope section, in an electrode assembly.

24. In any one of claims 1 to 23, a first non-circulating portion is disposed at the axial first end of the electrode assembly, wherein the surface of the first current collector of the first electrode is exposed, and An electrode assembly in which at least a portion of the first non-removable portion provides a first electrode tab of the first electrode.

25. The electrode assembly according to claim 24, wherein the first non-removable portion is electrically connected by being joined to a first current collector plate disposed at the first axial end of the electrode assembly.

26. In claim 24, a second non-circulating portion is disposed at the axial second end of the electrode assembly opposite to the axial first end, wherein the surface of the second current collector of the second electrode is exposed. An electrode assembly in which at least a portion of the second non-removable portion provides a second electrode tab of the second electrode.

27. An electrode assembly according to claim 26, wherein the second non-electrical portion is joined to and electrically connected to a second current collector plate disposed at the axial second end of the electrode assembly.

28. An electrode assembly of any one of claims 1 to 23; and A battery cell comprising a case housing the above electrode assembly.

29. The battery cell according to claim 28, wherein the case comprises a first electrode terminal electrically connected to the first electrode and a second electrode terminal electrically insulated from the first electrode terminal and electrically connected to the second electrode.

30. In claim 29, the first electrode terminal is provided on the surface of a metal can, and The above second electrode terminal is provided to a terminal member installed through the can, a battery cell.

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