Electrode assembly and secondary battery including the same

Abstract

The invention relates to an electrode assembly and a secondary battery including the same. The electrode assembly according to the present disclosure comprises: a first electrode connected to a first electrode tab; a second electrode connected to the second electrode tab; and a separator between the first electrode and the second electrode. The first electrode, the separator, and the second electrode are sequentially stacked and wound around a winding axis such that the electrode assembly includes a core portion having a central hole formed therein and an outer portion connected to the core portion. A length of the core portion in a direction of the winding axis is different from a length of the outer portion in the direction of the winding axis.

Description

Technical Field

[0001] This disclosure relates to an electrode assembly and a secondary battery including the electrode assembly. Background Technology

[0002] Unlike primary batteries, which are not designed for (re)charging, secondary (or rechargeable) batteries are designed to discharge and be recharged. Low-capacity secondary batteries are used in portable small electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while high-capacity secondary batteries are widely used as power sources for motors in hybrid and electric vehicles, as well as for storing electricity (e.g., household and / or utility-scale power storage). A secondary battery typically includes an electrode assembly containing positive and negative electrodes, a housing that houses the electrode assembly, and electrode terminals connected to the electrode assembly.

[0003] In secondary batteries, energy density is the amount of energy that can be stored per unit volume. High energy density secondary batteries provide increased operating time in portable devices and increased driving range in electric vehicles. Accordingly, the energy density of secondary batteries is considered one of the important factors determining their performance, and various efforts have been made to improve it.

[0004] The information disclosed above in this background section is intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute related (or prior art). Summary of the Invention

[0005] One aspect of this disclosure provides an electrode assembly and a secondary battery including the electrode assembly.

[0006] These and other aspects and features of this disclosure will be described in or will be apparent from the following description of embodiments of this disclosure.

[0007] According to one embodiment of this disclosure, an electrode assembly is provided, comprising: a first electrode connected to a first electrode terminal; a second electrode connected to a second electrode terminal; and a diaphragm located between the first electrode and the second electrode, wherein the first electrode, the diaphragm, and the second electrode are stacked sequentially and wound around a winding axis such that the electrode assembly includes a core portion and an outer portion connected to the core portion, the core portion having a central hole formed therein, and the length of the core portion in the direction of the winding axis being different from the length of the outer portion in the direction of the winding axis.

[0008] According to one embodiment, the outer portion may include a first outer portion connected to the core portion and a second outer portion connected to the first outer portion, wherein the length of the first outer portion in the direction of the winding axis may be shorter than the length of the core portion in the direction of the winding axis, and the length of the second outer portion in the direction of the winding axis may be shorter than the length of the first outer portion in the direction of the winding axis.

[0009] According to one embodiment, the first electrode tab and the second electrode tab may protrude from the first outer portion.

[0010] According to one embodiment, the electrode assembly may have: a first outer surface formed by the core portion; a second outer surface formed by the first outer portion; and a third outer surface formed by the second outer portion.

[0011] According to one embodiment, the top of the core portion, the top of the first outer portion, and the top of the second outer portion may extend along lines parallel to each other, the first outer surface may be perpendicular to the top of the core portion and the top of the first outer portion, and the second outer surface may be perpendicular to the top of the first outer portion and the top of the second outer portion.

[0012] According to one embodiment, the top of the core portion, the top of the first outer portion, and the top of the second outer portion may extend along lines parallel to each other, and the first outer surface and the second outer surface may be radially outward from the core portion and the first outer portion, respectively.

[0013] According to one embodiment of the present invention for solving a technical problem, a secondary battery is provided, comprising: an electrode assembly; a cylindrical housing for receiving the electrode assembly; a cover for sealing an opening of the cylindrical housing; and a gasket between the cover and the cylindrical housing, wherein the electrode assembly comprises: a first electrode connected to a first electrode terminal; a second electrode connected to a second electrode terminal; and a separator between the first electrode and the second electrode, wherein the first electrode, the separator, and the second electrode are sequentially stacked and wound around a winding axis to form the electrode assembly, and the electrode assembly includes a core portion and an outer portion connected to the core portion, the core portion having a central hole formed therein, and the length of the core portion in the direction of the winding axis being longer than the length of the outer portion in the direction of the winding axis.

[0014] According to one embodiment, the cover plate may include: a first flat portion located at the center of the cover plate and protruding in a direction away from the electrode assembly housed in the cylindrical housing; a second flat portion located outside the first flat portion; and a connecting portion located between the first flat portion and the second flat portion.

[0015] According to one embodiment, the connecting portion may be radially outward from the first flat portion.

[0016] According to one embodiment, a notch may be formed in the lower surface of the second flat portion.

[0017] According to one embodiment, the outer portion may include: a first outer portion connected to the core portion; and a second outer portion connected to the first outer portion, wherein the length of the first outer portion in the direction of the winding axis may be shorter than the length of the core portion in the direction of the winding axis, and the length of the second outer portion in the direction of the winding axis may be shorter than the length of the first outer portion in the direction of the winding axis.

[0018] According to one embodiment, the first electrode tab may protrude from the first outer portion and connect to the second flat portion of the cover plate.

[0019] According to one embodiment, the second electrode tab may protrude from the first outer portion and connect to the bottom portion of the housing.

[0020] According to one embodiment, an insulating member may be further provided between the cover plate and the electrode assembly.

[0021] According to one embodiment, the electrode assembly may have: a first outer surface formed by the core portion; a second outer surface formed by the first outer portion; and a third outer surface formed by the second outer portion.

[0022] According to one embodiment, the top of the core portion, the top of the first outer portion, and the top of the second outer portion may extend along lines parallel to each other, the first outer surface may be perpendicular to the top of the core portion and the top of the first outer portion, and the second outer surface may be perpendicular to the top of the first outer portion and the top of the second outer portion.

[0023] According to one embodiment, the top of the core portion, the top of the first outer portion, and the top of the second outer portion may extend along lines parallel to each other, and the first outer surface and the second outer surface may be radially outward from the core portion and the first outer portion, respectively.

[0024] According to one embodiment, the top of the core portion may be higher than the bottom of the second flat portion of the cover plate in the direction of the winding axis.

[0025] According to one embodiment, the top of the second outer portion may be higher than the bottom of the pad in the direction of the winding axis.

[0026] According to one embodiment, the longest diameter of the first outer portion may be shorter than the diameter of the circle formed by the inner surface of the liner.

[0027] According to some embodiments of this disclosure, electrode assemblies and secondary batteries with improved energy density can be provided.

[0028] According to some embodiments of this disclosure, the energy density of a secondary battery can be increased by configuring the shape of the electrode assembly and positioning the electrode assembly in an unused space inside the housing.

[0029] According to some embodiments of this disclosure, only a cover plate is provided as a component for sealing the upper part of the cylindrical housing, and no other components with current blocking function are provided, thereby providing more space to accommodate the electrode assembly and thus improving the energy density of the secondary battery.

[0030] According to some embodiments of this disclosure, when the shape of the cover and the gasket changes, the shape of the electrode assembly changes accordingly, and the electrode assembly is located in an open space inside the housing, thereby improving the energy density of the secondary battery.

[0031] However, the aspects and features of this disclosure are not limited to those described above, and those skilled in the art will clearly understand from the detailed description other aspects and features not mentioned. Attached Figure Description

[0032] The accompanying drawings illustrate embodiments of the present disclosure and, together with the detailed description of the present disclosure, further describe aspects and features of the present disclosure. This disclosure should not be construed as limited to the drawings.

[0033] Figure 1 This is a perspective view illustrating an example of a secondary battery according to an embodiment of the present disclosure.

[0034] Figure 2 This is a cross-sectional view showing an example of a secondary battery according to an embodiment of the present disclosure.

[0035] Figure 3 This is a diagram illustrating an example of an electrode assembly before and after winding, according to an embodiment of the present disclosure.

[0036] Figure 4This is a cross-sectional view illustrating an example of an electrode assembly according to an embodiment of the present disclosure.

[0037] Figure 5 Examples of electrode assemblies according to embodiments of the present disclosure are shown before and after winding.

[0038] Figure 6 This is a cross-sectional view of an electrode assembly according to an embodiment of the present disclosure.

[0039] Figure 7 This is a perspective view illustrating an example of an insulating member according to an embodiment of the present disclosure.

[0040] Figure 8 This is a perspective view illustrating an example of an insulating member according to an embodiment of the present disclosure.

[0041] Figure 9 This is a perspective view showing an example of a cover plate according to an embodiment of the present disclosure.

[0042] Figure 10 This is a cross-sectional view of the cover plate according to an embodiment of the present disclosure.

[0043] Figure 11 This is a cross-sectional view of the upper portion of a secondary battery according to an embodiment of the present disclosure.

[0044] Figure 12 This is a cross-sectional view of the upper portion of a secondary battery according to an embodiment of the present disclosure.

[0045] Explanation of reference numerals in the attached figures

[0046] 100: Secondary battery; 120: Casing

[0047] 122: Bottom section; 126: Rolled section

[0048] 128: Crimped part; 130: Cover plate

[0049] 132: First flat portion; 134: Connecting portion

[0050] 136: Second flat portion; 139: Notch

[0051] 140: Pad; 150: Insulation material

[0052] 200: Electrode assembly; 210: First electrode

[0053] 212: First electrode connector; 220: Second electrode

[0054] 222: Second electrode connector; 230: Diaphragm

[0055] 260: Core portion; 262: First outer surface

[0056] 270: Outer Part 270_1: First Outer Part

[0057] 270_2: Second outer part; 272_1: Second outer surface

[0058] 272_2: Third outer surface Detailed Implementation

[0059] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The terms or words used in this specification and claims should not be construed as limited to their general or dictionary meanings, and should be interpreted in a manner consistent with the technical spirit of the present disclosure, based on the principle that the inventor is capable of interpreting the concepts of the terms appropriately as his / her own lexicographer.

[0060] The embodiments described in this specification and the configurations shown in the accompanying drawings are only some of the embodiments of this disclosure and do not represent all the technical ideas, aspects, and features of this disclosure. Accordingly, it should be understood that various equivalents and modifications that can replace or modify the embodiments described herein may exist at the time of filing this application.

[0061] It will be understood that when an element or layer is referred to as being "on" another element or layer, "connected to," or "linked to" another element or layer, it can be directly on, directly connected to, or linked to the other element or layer, or one or more intermediary elements or layers may be present. When an element or layer is referred to as being "directly on" another element or layer, "directly connected to," or "directly linked to" another element or layer, no intermediary element or layer is present. For example, when a first element is described as being "linked" or "connected" to a second element, the first element can be directly linked to or connected to the second element, or the first element can be indirectly linked to or connected to the second element via one or more intermediary elements.

[0062] In the figures, the dimensions of various elements, layers, etc., may be exaggerated for clarity of illustration. The same reference numerals denote the same elements. As used herein, the term “and / or” includes any and all combinations of one or more of the related listed items. Furthermore, when describing embodiments of this disclosure, the use of “may” refers to “one or more embodiments of this disclosure.” Expressions such as “at least one of…” and “any one of…” modify the entire list of elements when following it, and not individual elements within that list. When phrases such as “at least one of A, B, and C,” “at least one of A, B, or C,” “at least one selected from the group of A, B, and C,” or “at least one selected from A, B, and C” are used to refer to a list of elements A, B, and C, the phrase may refer to any one of A, B, and C and all suitable combinations or subsets of them, such as A, B, C, A and B, A and C, B and C, or A and B and C. As used herein, the term “use” may be considered synonymous with the term “utilize.” As used herein, the terms “substantially,” “about,” and similar terms are used as approximate terms and not as terms of degree, and are intended to describe the inherent variations in measured or calculated values ​​that would be recognized by one of ordinary skill in the art.

[0063] It will be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or segment from another element, component, region, layer, or segment. Therefore, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment.

[0064] For ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” and “above” are used herein to describe the relationship between one element or feature illustrated in the figure and another element or feature. It will be understood that spatial relative terms are intended to cover different orientations of the device in use or operation other than the orientation depicted in the figure. For example, if the device in the figure is flipped, an element described as “below” or “under” other elements or features will then be oriented as “above” or “above” other elements or features. Therefore, the term “below” can encompass both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptive terms used herein should be interpreted accordingly.

[0065] The terminology used herein is for the purpose of describing embodiments of this disclosure and is not intended to limit this disclosure. As used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprising” and / or “including” as used in this specification specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0066] Furthermore, any numerical range disclosed and / or described herein is intended to include all subranges with the same numerical precision contained within the described range. For example, the range “1.0 to 10.0” is intended to include all subranges between the described minimum value of 1.0 and the described maximum value of 10.0 (and inclusive of both), i.e., a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as 2.4 to 7.6. Any maximum numerical limit described herein is intended to include all lower numerical limits contained therein, and any minimum numerical limit described herein is intended to include all higher numerical limits contained therein. Accordingly, the applicant reserves the right to amend this specification, including the claims, to explicitly describe any subranges contained within the scope explicitly described herein.

[0067] Referring to two compared elements, features, etc., as “identical” can mean that they are “substantially identical.” Therefore, the phrase “substantially identical” can include cases where the deviation is considered low in the art (e.g., 5% or less). Additionally, when a parameter is said to be consistent in a given region, it can mean that it is consistent in terms of average value.

[0068] Throughout this specification, unless otherwise stated, each element may be singular or plural.

[0069] Placing any element "above (or below)" or "on (or under)" another element may mean that the arbitrary element can be configured to contact the upper (or lower) surface of the element, and other elements may also be located between the element and any element disposed on (or below) the element.

[0070] Additionally, it will be understood that when a component is referred to as “connected,” “linked,” or “attached” to another component, these components can be directly “connected,” “linked,” or “attached” to each other, or another component can be “between” these components.

[0071] Throughout this specification, unless otherwise stated, the phrase "A and / or B" means A, B, or A and B. That is, "and / or" includes any one or all of the listed items. Unless otherwise stated, the phrase "C to D" means C and below D.

[0072] In this disclosure, for clarity, the dimensions and relative dimensions of layers and regions shown in the accompanying drawings may be exaggerated. That is, the dimensions shown in the drawings are for ease of understanding only and are not limiting. Furthermore, the same reference numerals refer to the same parts throughout the specification.

[0073] Figure 1 This is a perspective view illustrating an example of a secondary battery according to an embodiment of the present disclosure, and Figure 2 This is a cross-sectional view showing an example of a secondary battery according to an embodiment of the present disclosure.

[0074] like Figure 1 and Figure 2 As shown, the secondary battery 100 may include an electrode assembly 200, a cylindrical housing 120 therein containing the electrode assembly 200 and an electrolyte, and a cover plate 130 connected to an opening in the cylindrical housing 120 to seal the cylindrical housing 120. An insulating member 150 may be located within the cylindrical housing 120 between the electrode assembly 200 and the cover plate 130.

[0075] Electrode assembly 200 may include a first electrode 210, a second electrode 220, and a diaphragm 230 located between the first electrode 210 and the second electrode 220. Electrode assembly 200 may be wound around a winding axis Y to form an electrode core shape. In another example, electrode assembly 200 may be formed by stacking multiple electrode plates and a diaphragm, the diaphragm being zig-folded and positioned between the electrode plates along the thickness direction.

[0076] According to one embodiment, the electrode assembly 200 may include a first electrode 210 connected to a first electrode tab 212, a second electrode 220 connected to a second electrode tab 222, and a diaphragm 230 between the first electrode 210 and the second electrode 220. The first electrode 210, the diaphragm 230, and the second electrode 220 may be stacked and wound sequentially. In the wound state, the electrode assembly 200 may include a core portion and an outer portion connected to the core portion, the core portion having a central hole formed therein. Here, the length of the core portion in the direction of the winding axis Y may be greater than the length of the outer portion in the direction of the winding axis Y. This will be described in more detail below.

[0077] The first electrode 210 includes a first substrate and a first active material layer on the first substrate. The first electrode tab 212 can extend outward from a first uncoated portion of the first substrate, the first active material layer is not located at the first uncoated portion, and the first electrode tab 212 can be electrically connected to the cover assembly 130.

[0078] The second electrode 220 includes a second substrate and a second active material layer on the second substrate. A second electrode tab 222 can extend outward from a second uncoated portion of the second substrate, where the second active material layer is not located, and the second electrode tab 222 can be electrically connected to the housing 120. The first electrode tab 212 and the second electrode tab 222 can extend in opposite directions.

[0079] The first electrode 210 can serve as a positive electrode. In such an embodiment, the first substrate can be made of, for example, aluminum foil, and the first active material layer can include, for example, a transition metal oxide. The second electrode 220 can serve as a negative electrode. In such an embodiment, the second substrate can be made of, for example, copper foil or nickel foil, and the second active material layer can include, for example, graphite.

[0080] The separator 230 prevents short circuits between the first electrode 210 and the second electrode 220 while allowing lithium ions to move between them. The separator 230 can be made of, for example, a polyethylene membrane, a polypropylene membrane, or a polyethylene-polypropylene membrane.

[0081] The housing 120 houses the electrode assembly 200 and, together with the cover plate 130, forms the appearance of the secondary battery 100. The housing 120 may have a generally cylindrical body portion 124 and a bottom portion 122 connected to one side (e.g., one end) of the body portion 124. An inwardly deformed rolled portion (e.g., a rolled section) 126 may be formed in the body portion 124, and an inwardly bent crimped portion (e.g., a crimped section) 128 may be formed at the open end of the body portion 124.

[0082] The crimping portion 126 can reduce or prevent movement of the electrode assembly 200 within the housing 120 and can facilitate the placement of the gasket 140 and the cover plate 130. The crimping portion 128 can securely hold the cover plate 130 in place by pressing the edge of the cover plate 130. The housing 120 can be formed of, for example, nickel-plated iron. The housing 120 can be made of steel, steel alloy, aluminum, or aluminum alloy.

[0083] The cover plate 130 can seal the opening of the cylindrical housing 120 to protect the electrode assembly 200 from the influence of the external environment. The cover plate 130 may include a notch 139. When the internal pressure of the cylindrical housing 120 becomes higher than a reference pressure, the cover plate 130 can rupture at the notch 139, thereby releasing the internal gas of the cylindrical housing 120 to the outside of the secondary battery 100.

[0084] The center of the cover plate 130 may protrude in a direction away from the electrode assembly 200. Thus, the cover plate 130 can be used as a positive terminal. The cover plate 130 may be made of aluminum or an aluminum alloy.

[0085] According to one embodiment, the cover plate 130 may include a first flat portion, a second flat portion, and a connecting portion. The first flat portion is located at the center and protrudes in a direction away from the electrode assembly 200 housed in the cylindrical housing 120. The second flat portion is located outside the first flat portion, and the connecting portion is located between the first flat portion and the second flat portion. This configuration will be described in more detail below.

[0086] The gasket 140 can provide insulation between the cover plate 130 and the housing 120. The gasket 140 can be formed of resin materials such as polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET).

[0087] The insulating member 150 may be positioned to contact the electrode assembly 200. The insulating member 150 may have a tab opening through which the first electrode tab 212 is led out. A cover plate 130 electrically connected to the first electrode 210 via the first electrode tab 212 may face the electrode assembly 200, and the insulating member 150 is positioned between the cover plate 130 and the electrode assembly 200, and the cover plate 130 may be kept insulated (e.g., electrically insulated) from the electrode assembly 200 by the insulating member 150.

[0088] An electrolyte is provided inside the cylindrical housing 120. During charging / discharging, the electrolyte allows the movement of lithium ions generated by electrochemical reactions at the negative and positive plates inside the battery. The electrolyte can be a non-aqueous organic electrolyte, which is a mixture of lithium salt and a high-purity organic solvent. In other cases, the electrolyte can be a polymer or solid electrolyte using a polymer electrolyte. However, the type of electrolyte is not limited in this disclosure.

[0089] Figure 3 Examples of electrode assemblies according to embodiments of the present disclosure are shown before and after winding, and Figure 4 This is a cross-sectional view of an electrode assembly according to an embodiment of the present disclosure.

[0090] Figure 3The left part is a plan view showing the shape of the electrode assembly of the secondary battery before winding, and Figure 3 The right part is a perspective view showing the shape of the electrode assembly of the secondary battery after it has been wound.

[0091] refer to Figure 3 The electrode assembly 200 may include a first electrode 210, a second electrode 220, and a diaphragm 230. Specifically, the electrode assembly 200 may be formed by winding the first electrode 210, the second electrode 220, and the diaphragm 230 between the first electrode 210 and the second electrode 220. The electrode assembly 200 may be wound to form a core portion 260, and the core portion 260 may include a central hole 250. The electrode assembly 200 may include a first electrode tab 212 connected to the first electrode 210 and a second electrode tab 222 connected to the second electrode 220.

[0092] The first electrode 210 may include a first substrate having a first uncoated portion and a first electrode tab 212 connected to the surface of the first uncoated portion. The first electrode 210 may also include a first active material layer coated with a first active material. The first electrode tab 212 extends outward from the first uncoated portion of the first substrate without the active material layer, and the first electrode tab 212 may be electrically connected to the cover plate 130 (see...). Figure 2 ).

[0093] The second electrode 220 may include a second substrate having a second uncoated portion and a second electrode tab 222 connected to the surface of the second uncoated portion. The second electrode 220 may also include a second active material layer coated with a second active material. The second electrode tab 222 may extend outward from the second uncoated portion of the second substrate where the second active material layer is not coated, and the second electrode tab 222 may be electrically connected to the housing 120 (see [link to housing 120]). Figure 2 ).

[0094] The electrode assembly 200 can be wound from left to right (X direction), such as... Figure 3 The drawing direction is shown below. In the following text, the X direction will be referred to as the winding direction, and based on... Figure 3 The drawing direction indicates that the left end of the first electrode 210 and the second electrode 220 refers to the front end of the winding, and the right end refers to the end of the winding.

[0095] Here, the winding tip refers to the region where winding begins during the winding process of the electrode assembly 200, and the winding end refers to the region where winding ends during the winding process of the electrode assembly 200. Accordingly, the positions where the first electrode tab 212 and the second electrode tab 222 protrude from the wound electrode assembly 200 can be set according to the positions where the first electrode tab 212 and the second electrode tab 222 are connected to the first electrode 210 and the second electrode 220. For example, the first electrode tab 212 located at the winding end can be located on the outer periphery of the wound electrode assembly 200. That is, the winding end can be located at the outermost portion of the electrode assembly 200. As another example, the first electrode tab 212 located at the winding tip can be located on the inner periphery of the wound electrode assembly 200. That is, the winding tip can be located at the innermost portion of the electrode assembly 200.

[0096] The first electrode 210 can be used as a positive electrode. In this case, the first substrate can be made of, for example, aluminum foil, and the first active material can include, for example, a transition metal oxide.

[0097] The positive electrode for a rechargeable lithium battery may include a current collector and a layer of positive electrode active material on the current collector. The positive electrode active material layer may include a positive electrode active material and may further include a binder and / or a conductive material (e.g., an electrically conductive material).

[0098] For example, the positive electrode may further include additives that can be used as a sacrificial positive electrode.

[0099] Based on a 100wt% positive electrode active material layer, the amount of positive electrode active material can be from about 90wt% to about 99.5wt%. Based on a 100wt% positive electrode active material layer, the amounts of binder and conductive material can be from about 0.5wt% to about 5wt%, respectively.

[0100] The binder is used to attach positive electrode active material particles to each other, and also to attach positive electrode active material to a current collector. As a non-limiting example, examples of binders may include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, nylon, etc.

[0101] Conductive materials can be used to impart conductivity (e.g., electrical conductivity) to electrodes. Any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in a rechargeable lithium battery) and conducts electrons can be used in the battery. Examples of conductive materials can include: carbon-based materials such as natural graphite, synthetic graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metal-based materials comprising copper, nickel, aluminum, silver, etc., in the form of metal powders or metal fibers; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0102] Al can be used as a current collector, but this disclosure is not limited thereto.

[0103] The positive electrode active material may include compounds capable of intercalating and deintercalating lithium (lithiation intercalation compounds). Specifically, at least one of lithium and a composite oxide of a metal selected from cobalt, manganese, nickel, and combinations thereof may be used.

[0104] The composite oxide can be a lithium transition metal composite oxide. Specific examples of composite oxides may include lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, cobalt-free nickel manganese-based oxides, or combinations thereof.

[0105] As an example, the following compounds, represented by any of the following chemical formulas, can be used. Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0<α<2); Li a Ni b Co c L1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, and 0≤e≤0.1); Li a NiG b O2 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn 1-b G b O2 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn 1-g G g PO4 (0.90≤a≤1.8, and 0≤g≤0.5); Li (3-f) Fe2(PO4)3 (0≤f≤2); or Li a FePO4 (0.90≤a≤1.8).

[0106] In the above chemical formulas, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; and L 1 It is Mn, Al, or a combination thereof.

[0107] The positive electrode active material can be, for example, a high-nickel-based positive electrode active material, based on 100 mol% of metals other than lithium in a lithium transition metal composite oxide. This high-nickel-based positive electrode active material has a nickel content greater than or equal to about 80 mol%, greater than or equal to about 85 mol%, less than or equal to about 90 mol%, greater than or equal to about 91 mol%, or greater than or equal to about 94 mol% and less than or equal to about 99 mol%. High-nickel-based positive electrode active materials can achieve high capacity and can be applied to high-capacity, high-density rechargeable lithium secondary batteries.

[0108] The second electrode 220 can be used as a negative electrode. In this case, the second substrate can be formed of, for example, copper foil or nickel foil, and the second active material can include, for example, graphite.

[0109] The negative electrode for a rechargeable lithium battery may include a current collector and a negative electrode active material layer on the current collector. The negative electrode active material layer may include a negative electrode active material and may further include a binder and / or a conductive material (e.g., an electrically conductive material).

[0110] For example, the negative electrode active material layer may include from about 90 wt% to about 99 wt% of a negative electrode active material, from about 0.5 wt% to about 5 wt% of a binder, and from about 0 wt% to about 5 wt% of a conductive material.

[0111] The negative current collector may include a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foam, a copper foam, a polymer substrate coated with a conductive metal, or a combination thereof.

[0112] The negative electrode active material may include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / de-doping lithium, or a transition metal oxide.

[0113] The material capable of reversibly intercalating / deintercalating lithium ions may include a carbon-based negative electrode active material, such as crystalline carbon, amorphous carbon, or a combination thereof as examples. The crystalline carbon may be graphite, such as natural graphite or artificial graphite that is amorphous, plate-like, flaky, spherical, or fibrous. The amorphous carbon may be soft carbon, hard carbon, a mesophase pitch carbonized product, sintered coke, etc.

[0114] The lithium metal alloy includes an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0115] The material capable of doping / de-doping lithium may be a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material may include silicon, a silicon-carbon composite, SiO x (0 < x < 2), a Si-Q alloy (where Q is selected from alkali metals, alkaline earth metals, group 13 elements, group 14 elements (excluding Si), group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof). The Sn-based negative electrode active material may include Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0116] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the silicon-carbon composite may include secondary particles (cores) in which primary silicon particles are aggregated and an amorphous carbon coating (shell) on the surface of the secondary particles. The amorphous carbon may also be between the primary silicon particles, and for example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed in the amorphous carbon matrix.

[0117] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core comprising crystalline carbon and silicon particles, and an amorphous carbon coating on the surface of the core.

[0118] Si-based or Sn-based negative electrode active materials can be used in combination with carbon-based negative electrode active materials.

[0119] The separator 230 serves to prevent short circuits between the first electrode 210 and the second electrode 220 while allowing lithium ions to move. The separator 230 can be formed of, for example, a polyethylene membrane, a polypropylene membrane, or a polyethylene-polypropylene membrane, but is not limited to these.

[0120] The diaphragm 230 may include a multilayer membrane of polyethylene, polypropylene, polyvinylidene fluoride or two or more layers thereof, as well as a mixed multilayer membrane (such as a polyethylene / polypropylene two-layer diaphragm, a polyethylene / polypropylene / polyethylene three-layer diaphragm, a polypropylene / polyethylene / polypropylene three-layer diaphragm, etc.).

[0121] The diaphragm 230 may include a porous substrate and a coating on one or both surfaces of the porous substrate, comprising organic materials, inorganic materials or combinations thereof.

[0122] Porous substrates can be made from polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate and polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyetherketones, polyaryletherketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene ethers, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fibers, and polytetrafluoroethylene (e.g., A polymer film formed from any one of the polymers selected, or a copolymer or mixture of two or more of them.

[0123] Organic materials may include polyvinylidene fluoride polymers or (meth)acrylic acid polymers.

[0124] Inorganic materials may include, but are not limited to, inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite and combinations thereof.

[0125] Organic and inorganic materials can be mixed in a coating, or coatings containing organic materials and coatings containing inorganic materials can be stacked.

[0126] According to one embodiment, the first electrode 210, the diaphragm 230, and the second electrode 220 can be stacked and wound sequentially to form an electrode assembly 200. Therefore, the shapes of the first electrode 210, the diaphragm 230, and the second electrode 220 determine the shape of the wound electrode assembly 200. Figure 3 As shown, the first electrode 210, the diaphragm 230, and the second electrode 220 may include steps such that the height (e.g., length in the direction of the winding axis Y) of the first electrode 210, the second electrode 202, and the diaphragm 230 decreases along the winding direction (i.e., the X direction). Accordingly, the winding tip may protrude in the direction of the winding axis Y and be located at the innermost part of the wound electrode assembly 200, and the winding end may be located at the outermost part of the wound electrode assembly 200.

[0127] The first electrode 210, diaphragm 230, and second electrode 220 can be stacked and wound sequentially. In the wound state, the electrode assembly 200 may include a core portion 260 and an outer portion 270 connected to the core portion 260, the core portion 260 having a central hole 250 formed therein. The length of the core portion 260 in the direction of the winding axis Y is different from the length of the outer portion 270 in the direction of the winding axis Y. Figure 3 As shown, the outer portion 270 includes a first outer portion 270_1 connected to the core portion 260 and a second outer portion 270_2 connected to the first outer portion 270_1. The length of the first outer portion 270_1 in the direction of the winding axis Y may be less than the length of the core portion 260 in the direction of the winding axis Y, and the length of the second outer portion 270_2 in the direction of the winding axis Y may be less than the length of the first outer portion 270_1 in the direction of the winding axis Y.

[0128] According to one embodiment, the first electrode tab 212 and the second electrode tab 222 may be located between the winding front end and winding end of the first electrode 210 and the second electrode 220. Accordingly, the first electrode tab 212 and the second electrode tab 222 may protrude from the first outer portion 270_1 of the electrode assembly 200. However, this disclosure is not limited to this configuration.

[0129] According to one embodiment, the electrode assembly 200 may have a first outer surface 262 formed by a core portion 260, a second outer surface 272_1 formed by the first outer portion 270_1, and a third outer surface 272_2 formed by the second outer portion 270_2. For example... Figure 4 As shown, the top of the core portion 260, the top of the first outer portion 270_1, and the top of the second outer portion 270_2 are parallel to each other. The first outer surface 262 is perpendicular to the top of the core portion 260 and the top of the first outer portion 270_1, and the second outer surface 272_1 may be perpendicular to the top of the first outer portion 270_1 and the top of the second outer portion 270_2.

[0130] Using the aforementioned electrode assembly 200, the shape of the electrode assembly 200 allows it to fill spaces inside the housing that would otherwise be empty. Therefore, for a given secondary battery, the amount of electrode assembly 200 housed inside the housing increases, thereby improving the energy density of the secondary battery.

[0131] Figure 5 Examples of electrode assemblies according to embodiments of the present disclosure before and after winding, and Figure 6 This is a cross-sectional view illustrating an example of an electrode assembly according to an embodiment of the present disclosure. The following will be described... Figure 5 and Figure 6 The configuration shown is the same as Figure 3 and Figure 4 The differences between the configurations shown.

[0132] refer to Figure 5 and Figure 6 The electrode assembly 500 may include a first electrode tab 512 connected to the first electrode 510 and a second electrode tab 522 connected to the second electrode 520. The first electrode 510, the diaphragm 530, and the second electrode 520 may include regions whose height gradually decreases in the direction of the winding axis Y. The winding front end may protrude in the direction of the winding axis Y and be located at the innermost part of the winding electrode assembly 500, and the winding end may be located at the outermost part of the winding electrode assembly 500.

[0133] According to one embodiment, the electrode assembly 500 may have a first outer surface 562 formed by a core portion 560, a second outer surface 572_1 formed by a first outer portion 570_1, and a third outer surface 572_2 formed by a second outer portion 570_2. The core portion 560 may have a central hole 550 formed therein. According to one embodiment, the tops of the core portion 560, the tops of the first outer portion 570_1, and the tops of the second outer portion 570_2 are parallel to each other, and the first outer surface 562 and the second outer surface 572_1 are inclined in a radially outward direction. With this shape, the electrode assembly 500 can be located in a space inside the housing that would otherwise not be used, thereby increasing the energy density of the secondary battery.

[0134] Figure 7 This is a perspective view of an insulating member according to an embodiment of the present disclosure.

[0135] refer to Figure 7The insulating member 150 may include a first protrusion 152, a second protrusion 154 surrounding the first protrusion 152, and a flat portion 158 surrounding the second protrusion 154. The first protrusion 152, the second protrusion 154, and the flat portion 158 have different heights and may include a step in the direction of the winding axis Y.

[0136] According to one embodiment, the first protrusion 152, the second protrusion 154, and the flat surface 158 of the insulating member 150 may be flat surfaces extending along lines parallel to each other. Here, the first protrusion 152 and the second protrusion 154 may protrude relative to the flat portion 158 in one direction. When the insulating member 150 is located above the electrode assembly, the first protrusion 152 and the second protrusion 154 may be positioned between the cover plate and the electrode assembly, facing away from the electrode assembly. The insulating member 150 thereby insulates the cover plate from the electrode assembly.

[0137] The insulating member 150 may include a tab opening 156 through which a first electrode tab may extend. In one example, the tab opening 156 is formed in a second protrusion 154. A plurality of such tab openings may be spaced at regular intervals around the first protrusion 152. Specifically, the plurality of tab openings 156 may be arranged at regular intervals along the periphery of a circle. In a particular embodiment, four tab openings are arranged at 90° intervals within a circle surrounding the first protrusion 152. However, the arrangement and number of tab openings 156 are not limited to the depicted embodiment. That is, in other embodiments, the arrangement and number of tab openings 156 may be different.

[0138] The outer surface of the insulating member 150 may extend along a line perpendicular to the first protrusion 152, the second protrusion 154, and the flat surface 158. Here, the first protrusion 152, the second protrusion 154, and the flat surface 158 may be flat surfaces extending along lines parallel to each other. Thus, the outer surface of the electrode assembly perpendicular to the top of the electrode assembly can be easily covered by the insulating member 150.

[0139] Figure 8 This is a perspective view of an insulating member according to an embodiment of the present disclosure. The description will follow. Figure 8 The insulating components shown in the figure are Figure 7 Different aspects of the insulating components are shown in the figure.

[0140] refer to Figure 8 The insulating member 850 may include a first protrusion 852, a second protrusion 854 surrounding the first protrusion 852, and a flat portion 858 surrounding the second protrusion 854. In one example, a tab opening 856 is formed in the second protrusion 854.

[0141] According to one embodiment, the outer surface of the insulating member 850 may be radially outwardly inclined. Here, the first protrusion 852, the second protrusion 854, and the flat surface 858 may be flat surfaces extending along lines parallel to each other. Therefore, the radially outwardly inclined outer surface of the electrode assembly can be easily covered using the insulating member 850.

[0142] Figure 9 This is a perspective view illustrating an example of a cover plate according to an embodiment of the present disclosure, and Figure 10 This is a cross-sectional view showing an example of a cover plate according to an embodiment of the present disclosure.

[0143] refer to Figure 9 and Figure 10 The cover plate 130 may include a first flat portion 132, a second flat portion 136, and a connecting portion 134 located between the first flat portion 132 and the second flat portion 136. The first flat portion 132 may be located at the center of the cover plate 130. The second flat portion 136 may be located outside the first flat portion 132. Specifically, the second flat portion 136 may be located at the outer end of the first flat portion 132. Here, the outer end means at the point where the cover plate 130 is assembled to the cylindrical housing 120 (see...). Figure 2 ( ) is located or in a region radially away from the center of the cylindrical shell 120.

[0144] According to one embodiment, the first flat portion 132 may protrude relative to the second flat portion 136. Specifically, when the cover plate 130 seals the cylindrical housing 120 (see...), Figure 2 When the first flat portion 132 is away from the electrode assembly 200 (see...), Figure 2 The first flat portion 132 protrudes in the direction of the first flat portion 132. Therefore, the first flat portion 132 can be connected to an external terminal so that current can pass through the first flat portion 132.

[0145] A connecting portion 134 is located between the first flat portion 132 and the second flat portion 136 to connect the first flat portion 132 and the second flat portion 136. The connecting portion 134 can be radially inclined from the first flat portion 132. Furthermore, the inner end of the second flat portion 136 can be radially outwardly positioned from the outer end of the first flat portion 132.

[0146] The cover plate 130 may include a notch 139 formed in the lower surface of the second flat portion 136. The notch 139 may be formed to a certain depth in the lower surface of the second flat portion 136. The notch 139 may be formed continuously or discontinuously along the circumferential direction on the lower surface of the second flat portion 136. When the internal pressure of the secondary battery becomes greater than the operating pressure of the cover plate 130, the notch 139 ruptures, thereby allowing the internal gas of the cylindrical housing 120 to be released to the outside. Therefore, the secondary battery is safer. The secondary battery according to one embodiment of the present disclosure has only a cover plate 130 provided as a component for sealing the upper portion of the cylindrical housing 120, and no other components with current blocking function are provided. Therefore, additional space is provided for accommodating the larger electrode assembly 200 according to the present disclosure, thereby increasing the energy density of the secondary battery.

[0147] Figure 11 This is a cross-sectional view showing an example of the upper portion of a secondary battery according to an embodiment of the present disclosure. The description will follow. Figure 11 The configuration shown in the image is the same as... Figure 2 The differences between the configurations shown in the diagram.

[0148] refer to Figure 11 The cover plate 130 may include a first flat portion 132, a second flat portion 136, and a connecting portion 134 located between the first flat portion 132 and the second flat portion 136. A gasket 140 may be located between the cover plate 130 and the cylindrical housing 120. Specifically, the second flat portion 136 may be fixed to the cylindrical housing 120 via the gasket 140.

[0149] The gasket 140 can provide insulation between the cover plate 130 and the cylindrical housing 120. In one embodiment, the gasket 140 is wound around the outer edge of the second flat portion 136 of the cover plate 130. The outer surface of the gasket 140 can contact the crimp portion 126 and the crimp portion 128, and the inner surface of the gasket 140 can contact the second flat portion 136. The height of the first flat portion 132 (in the direction of the winding axis Y) can be greater than or equal to the height of the crimp portion 128 at the top of the cylindrical housing 120.

[0150] According to one embodiment, a first electrode tab 212 may protrude from the first outer portion 270_1 and connect to the second flat portion 136 of the cover plate 130. Although not shown, a second electrode tab 222 protrudes from the first outer portion 270_1 and may connect to the bottom portion 122 of the cylindrical housing 120 (see [link to documentation]). Figure 2 ).

[0151] The top of the core portion 260, the top of the first outer portion 270_1, and the top of the second outer portion 270_2 extend along lines parallel to each other. The first outer surface 262 may be perpendicular to the top of the core portion 260 and the top of the first outer portion 270_1, and the second outer surface 272_1 may be perpendicular to the top of the first outer portion 270_1 and the top of the second outer portion 270_2.

[0152] The top of the core portion 260 may be higher than the bottom of the second flat portion 136 of the cover plate 130 (in Figure 11 (In the direction of the winding axis Y shown). Additionally, the top of the core portion 260 may be higher than the top of the second flat portion 136 of the cover plate 130. The longest diameter D1 of the core portion 260 may be greater than or equal to the diameter D2 of the first flat portion 132. In other embodiments, the longest diameter D1 of the core portion 260 may be less than the diameter D2 of the first flat portion 132.

[0153] The top of the first outer portion 270_1 can be higher than the bottom of the pad 140 in the direction of the winding axis Y. The longest diameter D3 of the first outer portion 270_1 can be smaller than the diameter D4 of the circle formed by the inner surface of the pad 140. Therefore, the electrode assembly 200 can be located in an open space inside the cylindrical housing 120, thereby improving the energy density of the secondary battery.

[0154] Figure 12 This is a cross-sectional view showing an example of the upper portion of a secondary battery according to an embodiment of the present disclosure. The description will follow. Figure 12 The configuration shown in the image is the same as... Figure 11 The differences between the configurations shown in the diagram.

[0155] refer to Figure 12 The top of the core portion 560, the top of the first outer portion 570_1, and the top of the second outer portion 570_2 can extend along lines parallel to each other, and the first outer surface 562 and the second outer surface 572_1 can be radially outwardly inclined. Accordingly, the electrode assembly 500 can be shaped to correspond to the shape of the cover plate 130 and the liner 140, thereby improving the energy density of the secondary battery.

[0156] Although the present disclosure has been described above with reference to embodiments thereof, the present disclosure is not limited thereto. Various modifications and variations can be made to it within the spirit of the present disclosure by those skilled in the art.

Claims

1. An electrode assembly, comprising: The first electrode is connected to the first electrode terminal block; The second electrode is connected to the second electrode terminal block; as well as A diaphragm is located between the first electrode and the second electrode. The first electrode, the diaphragm, and the second electrode are stacked sequentially and wound around a winding axis, such that the electrode assembly includes a core portion and an outer portion connected to the core portion, the core portion having a central hole formed therein, and The length of the core portion in the direction of the winding axis is different from the length of the outer portion in the direction of the winding axis.

2. The electrode assembly of claim 1, wherein the outer portion comprises a first outer portion connected to the core portion and a second outer portion connected to the first outer portion. Wherein the length of the first outer portion in the direction of the winding axis is shorter than the length of the core portion in the direction of the winding axis, and The length of the second outer portion in the direction of the winding axis is shorter than the length of the first outer portion in the direction of the winding axis.

3. The electrode assembly according to claim 2, wherein the first electrode tab and the second electrode tab protrude from the first outer portion.

4. The electrode assembly according to claim 2, wherein the electrode assembly comprises: The first outer surface is formed by the core portion; The second outer surface is formed from the first outer portion; as well as The third outer surface is formed by the second outer portion.

5. The electrode assembly of claim 4, wherein the top of the core portion, the top of the first outer portion, and the top of the second outer portion extend along lines parallel to each other. Wherein the first outer surface is perpendicular to the top of the core portion and the top of the first outer portion, and The second outer surface is perpendicular to the top of the first outer portion and the top of the second outer portion.

6. The electrode assembly of claim 4, wherein the top of the core portion, the top of the first outer portion, and the top of the second outer portion extend along lines parallel to each other, and The first outer surface and the second outer surface are respectively inclined radially outward from the core portion and the first outer portion.

7. A secondary battery, comprising: Electrode assembly; A cylindrical housing to accommodate the electrode assembly; A cover plate that seals the opening of the cylindrical shell; as well as A gasket is located between the cover plate and the cylindrical shell. The electrode assembly includes: The first electrode is connected to the first electrode terminal block; The second electrode is connected to the second electrode terminal block; and A diaphragm, located between the first electrode and the second electrode, The first electrode, the diaphragm, and the second electrode are stacked sequentially and wound around a winding axis to form the electrode assembly. The electrode assembly includes a core portion and an outer portion connected to the core portion. The core portion has a central hole formed therein. The core portion is longer in the direction of the winding axis than the outer portion is in the direction of the winding axis.

8. The secondary battery according to claim 7, wherein the cover plate comprises: The first flat portion is located at the center of the cover plate and protrudes in a direction away from the electrode assembly housed in the cylindrical housing; The second flat portion is located outside the first flat portion; as well as The connecting portion is located between the first flat portion and the second flat portion.

9. The secondary battery according to claim 8, wherein the connecting portion is radially outward from the first flat portion.

10. The secondary battery of claim 8, wherein a notch is formed in the lower surface of the second flat portion of the cover plate.

11. The secondary battery according to claim 8, wherein the outer portion comprises: The first outer portion is connected to the core portion; as well as The second outer portion is connected to the first outer portion. Wherein the length of the first outer portion in the direction of the winding axis is shorter than the length of the core portion in the direction of the winding axis, and The length of the second outer portion in the direction of the winding axis is shorter than the length of the first outer portion in the direction of the winding axis.

12. The secondary battery of claim 11, wherein the first electrode tab protrudes from the first outer portion and is connected to the second flat portion of the cover plate.

13. The secondary battery of claim 11, wherein the second electrode tab protrudes from the first outer portion and is connected to the bottom portion of the cylindrical housing.

14. The secondary battery according to claim 7, further comprising an insulating member between the cover plate and the electrode assembly.

15. The secondary battery according to claim 11, wherein the electrode assembly comprises: The first outer surface is formed by the core portion; The second outer surface is formed from the first outer portion; as well as The third outer surface is formed by the second outer portion.

16. The secondary battery of claim 15, wherein the top of the core portion, the top of the first outer portion, and the top of the second outer portion extend along lines parallel to each other. Wherein the first outer surface is perpendicular to the top of the core portion and the top of the first outer portion, and The second outer surface is perpendicular to the top of the first outer portion and the top of the second outer portion.

17. The secondary battery of claim 15, wherein the top of the core portion, the top of the first outer portion, and the top of the second outer portion extend along lines parallel to each other. The first outer surface and the second outer surface are respectively inclined radially outward from the core portion and the first outer portion.

18. The secondary battery according to any one of claims 11 to 17, wherein the top of the core portion is higher than the bottom of the second flat portion of the cover plate in the direction of the winding axis.

19. The secondary battery according to any one of claims 11 to 17, wherein the top of the first outer portion is higher than the bottom of the pad in the direction of the winding axis.

20. The secondary battery according to any one of claims 11 to 17, wherein the longest diameter of the first outer portion is shorter than the diameter of the circle formed by the inner surface of the liner.

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