Secondary battery

Abstract

A secondary battery includes: an electrode assembly including a first electrode, a second electrode, and a separator therebetween; a case including a bottom portion, a sidewall portion connected to the bottom portion, and an opening portion facing the bottom portion, the case accommodating the electrode assembly; and a cover assembly coupled to one end of the side wall portion of the housing to seal the opening portion, in which the housing includes a groove region on an inner circumferential surface of the side wall portion.

Description

Technical Field

[0001] This disclosure relates to a secondary battery. Background Technology

[0002] Unlike primary batteries, which are not designed to be (re)charged, secondary (or rechargeable) batteries are designed to be discharged and 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 to drive motors in hybrid and electric vehicles and to store 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] The information disclosed in this background section is intended to enhance the understanding of the background art of this disclosure, and therefore may contain information that does not constitute related (or prior art). Summary of the Invention

[0004] The embodiment includes a secondary battery comprising: an electrode assembly including a first electrode, a second electrode, and a separator therebetween; a housing including a bottom portion, a sidewall portion connected to the bottom portion, and an opening portion facing the bottom portion, the housing accommodating the electrode assembly; and a cover assembly coupled to one end of the sidewall portion of the housing to seal the opening portion, wherein the housing includes a groove region formed on the inner peripheral surface of the sidewall portion.

[0005] The first electrode can be a positive electrode, and the second electrode can be a negative electrode.

[0006] In the direction of the winding axis of the electrode assembly, the length of the second electrode can be greater than the length of the first electrode.

[0007] Secondary batteries can include coin cells or button cells.

[0008] The material of the casing may include stainless steel.

[0009] The electrode assembly may further include a first electrode terminal connected to the first electrode and a second electrode terminal connected to the second electrode.

[0010] The first electrode connector can be connected to the cover assembly.

[0011] The second electrode connector can be connected to the bottom of the housing.

[0012] The inner peripheral surface may include a first inner peripheral surface located adjacent to the opening portion and a second inner peripheral surface located adjacent to the bottom portion, and the groove region may include: a first surface connected to the first inner peripheral surface, a third surface connected to the second inner peripheral surface, and a second surface connected to the first surface and the third surface.

[0013] The third surface can be perpendicular to the second inner circumferential surface.

[0014] The first surface may include an inclined surface, and the third surface may also include an inclined surface.

[0015] The first surface may include a curved surface, and the third surface may include a curved surface.

[0016] The first boundary line between the first inner circumferential surface and the first surface can correspond to the upper end of the second electrode, and the second boundary line between the second inner circumferential surface and the third surface can correspond to the lower end of the second electrode.

[0017] The boundary line between the first inner circumferential surface and the first surface can be separated from the end of the opening portion by a predetermined distance of 0.4 mm to 0.6 mm in the direction of the winding axis of the electrode assembly.

[0018] The boundary line between the second inner circumferential surface and the third surface can be separated from the bottom portion by a predetermined distance of 0.1 mm to 0.3 mm in the direction of the winding axis of the electrode assembly.

[0019] The distance between the boundary line between the second surface and the first inner circumferential surface and the first surface in a direction perpendicular to the winding direction of the electrode assembly can be equal to the distance between the boundary line between the second surface and the second inner circumferential surface and the third surface in a direction perpendicular to the winding direction of the electrode assembly.

[0020] The second surface can be separated from the boundary line between the first inner circumferential surface and the first surface by a predetermined distance of 0.01 mm to 0.07 mm in a direction perpendicular to the winding direction of the electrode assembly.

[0021] The first boundary line between the first inner circumferential surface and the first surface can be separated from the second boundary line between the second inner circumferential surface and the third surface by a predetermined distance in the winding axis direction of the electrode assembly.

[0022] The predetermined distance can correspond to the length of the second electrode.

[0023] The predetermined distance can be 2mm to 4mm.

[0024] However, the aspects and features of this disclosure are not limited to those described above, and other aspects and features not mentioned will be clearly understood by those skilled in the art from the detailed description described below. Attached Figure Description

[0025] Features will become apparent to those skilled in the art from the detailed description of exemplary embodiments with reference to the accompanying drawings, wherein:

[0026] Figure 1 This is a perspective view illustrating an example of a secondary battery according to one or more embodiments of the present disclosure;

[0027] Figure 2 These are illustrations of examples of electrode assemblies according to one or more embodiments of the present disclosure;

[0028] Figure 3 This is a cross-sectional view illustrating an example of a secondary battery according to a comparative example of the present disclosure;

[0029] Figure 4 This is a cross-sectional view illustrating an example of a secondary battery with an expanded electrode assembly according to a comparative example of the present disclosure;

[0030] Figure 5 This is a diagram illustrating an example of the shape of a groove region according to one or more embodiments of the present disclosure;

[0031] Figure 6 This is a cross-sectional view illustrating an example of a housing having a grooved region formed according to one or more embodiments of the present disclosure;

[0032] Figure 7 This is a cross-sectional view illustrating an example of a secondary battery having a slotted region according to one or more embodiments of the present disclosure;

[0033] Figure 8 This is a cross-sectional view illustrating an example of a secondary battery having an expanded electrode assembly according to one or more embodiments of the present disclosure;

[0034] Figure 9 This is a diagram illustrating an example of the shape of a groove region according to one or more embodiments of the present disclosure;

[0035] Figure 10 This is a cross-sectional view illustrating an example of a secondary battery having a slotted region according to one or more embodiments of the present disclosure;

[0036] Figure 11 These are illustrations illustrating examples of the shape of a groove region according to one or more embodiments of the present disclosure; and

[0037] Figure 12 This is a cross-sectional view illustrating an example of a secondary battery having a slotted area according to one or more embodiments of the present disclosure. Detailed Implementation

[0038] Exemplary embodiments will now be described more fully with reference to the accompanying drawings; however, they may be implemented in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey exemplary implementation methods to those skilled in the art.

[0039] In the accompanying drawings, for clarity of illustration, the dimensions of layers and regions may be enlarged. It will also be understood that when a layer or element is referred to as being "on" another layer or substrate, it may be directly on that layer or substrate, or there may be intermediate layers present. Furthermore, it will be understood that when a layer is referred to as being "below" another layer, it may be directly below, and one or more intermediate layers may be present. Additionally, it will be understood that when a layer is referred to as being "between" two layers, it may be the only layer between the two layers, or one or more intermediate layers may be present. The same reference numerals always indicate the same elements.

[0040] The terms or words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings, but should be interpreted as being consistent with the technical ideas of this disclosure, based on the principle that the inventor is capable of being his / her own lexicographer to properly define the terms and concepts in order to best interpret his / her embodiments.

[0041] 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. Therefore, 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.

[0042] It will be understood that when a component or layer is described as being "on," "connected to," or "attached to" another component or layer, it can be directly on, connected to, or attached to the other component or layer, or one or more intermediate components or layers may be present. When a component or layer is described as being "directly" on, directly connected to, or directly attached to another component or layer, no intermediate components or layers are present. For example, when a first component is described as being "attached" or "connected" to a second component, the first component can be directly attached to or connected to the second component, or the first component can be indirectly attached to or connected to the second component via one or more intermediate components.

[0043] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Furthermore, the use of “may” in describing embodiments of this disclosure refers to “one or more embodiments of this disclosure.” Expressions such as “at least one of…” and “any one of…” preceding / following the list of elements modify the entire list of elements, not individual elements in the 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 specify a list of elements A, B, and C, the phrase may refer to any and all suitable combinations or subsets of A, B, and C, 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 “generally,” “approximately,” and similar terms are used as approximate terms rather than terms of degree and are intended to account for inherent variations in measurements or calculations that are perceptible to those skilled in the art.

[0044] It will be understood that while the terms first, second, third, etc., may be used 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.

[0045] For ease of description, this document uses spatial relative terms such as “below,” “under,” “down,” “above,” and “up” to describe the relationship between one element or feature and another element or feature as shown in the figure. It should be understood that spatial relative terms are intended to include different orientations of the device in use or operation, in addition to 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 can be oriented; an element described as “below” or “under” other elements or features can be oriented; and “above” or “up” other elements or features can include both above and below orientations. The device can be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein should be interpreted accordingly.

[0046] The terminology used herein is for the purpose of describing embodiments of this disclosure and is not intended to be limiting of this disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. It should be further understood that when used in this specification, the terms “comprising” and / or “including” 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.

[0047] Furthermore, any numerical ranges disclosed and / or enumerated herein are intended to include all subranges with the same numerical precision contained within the enumerated ranges. For example, the range “1.0 to 10.0” is intended to include all subranges between the enumerated minimum value of 1.0 and the enumerated 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 enumerated herein is intended to include all lower numerical limits contained therein, and any minimum numerical limit enumerated in this specification is intended to include all higher numerical limits contained therein. Therefore, the applicant reserves the right to modify this specification, including the claims, to expressly enumerate any subranges contained within the scope expressly enumerated herein. All such ranges are intended to be inherently described in this specification such that modifications made to expressly enumerate any such subranges will comply with the applicable requirements.

[0048] Referring to two compared elements, features, etc., as “identical” may mean that they are “substantially identical.” Therefore, the phrase “substantially identical” can include cases with deviations considered low in the art, such as 5% or less. Furthermore, when a parameter is said to be consistent in a given region, this may mean that it is consistent in terms of its mean.

[0049] Throughout this specification, unless otherwise stated, each element may be singular or plural.

[0050] Placing any element "above (or below)" or "above (or below)" another element may mean that the arbitrary element can be positioned to contact the upper (or lower) surface of the element, and other elements may also be positioned between the element and any element positioned on (or below) the element.

[0051] Furthermore, it will be understood that when a component is referred to as “connected,” “linked,” or “attached” to another component, the components can be directly “connected,” “linked,” or “attached” to each other, or another component can be “between” the components.

[0052] Throughout this specification, unless otherwise stated, when “A and / or B” is stated, it means A, B, or A and B. In other words, “and / or” includes any or all combinations of the listed items. Unless otherwise indicated, when “C to D” is stated, it means greater than or equal to C and less than or equal to D.

[0053] In this disclosure, for clarity of description, the dimensions and relative dimensions of layers and regions shown in the accompanying drawings may be enlarged. For example, the dimensions shown in the drawings are for ease of understanding only and are not limiting. Throughout the specification, the same reference numerals denote the same parts.

[0054] Figure 1 This is a perspective view illustrating an example of a secondary battery according to one or more embodiments of the present disclosure.

[0055] refer to Figure 1 The secondary battery 100 may include a housing 120, a cover assembly 110, and an electrode assembly 210 (see...). Figure 2 ).

[0056] The secondary battery 100 can be a coin cell battery or a button cell battery. For example, the secondary battery 100 can have a cylindrical shape. However, the secondary battery 100 can be various shapes, such as square, pouch, or cylindrical batteries. In one example, the secondary battery 100 can be a rechargeable and dischargeable secondary battery.

[0057] The housing 120 can accommodate the electrode assembly 210 (see...) Figure 2 The housing 120 contains an electrolyte and can form the external shape of the secondary battery together with the cover assembly 110. The housing 120 may include a bottom portion, sidewall portions connecting to the bottom portion, and an opening facing the bottom portion. However, the housing 120 can have various shapes such as circular or pouch-like. The housing 120 can be made of metals such as stainless steel (SUS), aluminum (Al), aluminum alloys, nickel-plated steel, or laminated films or plastics forming a pouch.

[0058] The housing 120 can accommodate the electrode assembly 210 (see...) Figure 2 Electrode assembly 210 (see...) Figure 2 An insertable device can be inserted through an opening formed on one side of the housing 120. The opening of the housing 120 can then be sealed by a cover assembly 110. The opening of the housing 120 can be sealed by welding using the cover assembly 110. The cover assembly 110 can be connected to one end of a sidewall portion of the housing 120 to seal the opening.

[0059] According to one or more embodiments, the housing 120 may include a groove region formed on the inner circumferential surface of a sidewall portion. The groove region may be formed continuously along the inner circumferential surface of the sidewall portion. As another example, the groove region may be formed discontinuously along the inner circumferential surface of the sidewall portion. The inner circumferential surface may include a first inner circumferential surface positioned adjacent to an opening portion and a second inner circumferential surface positioned adjacent to a bottom portion. The groove region may include a first surface connected to the first inner circumferential surface, a third surface connected to the second inner circumferential surface, and a second surface connected to the first and third surfaces. Reference will be made below. Figures 5 to 12 Please describe this configuration in detail.

[0060] Figure 2 This is a diagram illustrating an example of an electrode assembly according to one or more embodiments of the present disclosure. Figure 2 The left-hand diagram is a plan view illustrating the shape of the electrode assembly of a secondary battery before it is wound. Figure 2 The diagram on the right is a perspective view illustrating the shape of the electrode assembly of a secondary battery after it has been wound.

[0061] According to one or more embodiments, the electrode assembly 210 may include a first electrode 212, a second electrode 214, and a diaphragm 215. For example, the electrode assembly 210 may be formed by winding the first electrode 212, the second electrode 214, and the diaphragm 215 therebetween. The electrode assembly 210 may be wound to form a core and may include through-holes in the core. The electrode assembly 210 may further include a first electrode tab 216 connected to the first electrode 212 and a second electrode tab 218 connected to the second electrode 214.

[0062] The first electrode 212 may include a first substrate member, a first uncoated portion formed on the first substrate member, and a first electrode tab 216 connected to a surface of the first uncoated portion. The first electrode 212 may include a first active material layer formed by coating a first active material. The first electrode tab 216 may extend outward from the first uncoated portion of the first substrate member to which the active material layer is not coated, and the first electrode tab 216 may be electrically connected to the terminal block of the cover assembly.

[0063] The second electrode 214 may include a second substrate member, a second uncoated portion formed on the second substrate member, and a second electrode tab 218 connected to a surface of the second uncoated portion. The second electrode 214 may include a second active material layer formed by coating a second active material. The second electrode tab 218 may extend outward from the second uncoated portion of the second substrate member to which the active material layer is not coated, and the second electrode tab 218 may be electrically connected to the housing.

[0064] The first electrode 212, the second electrode 214, and the diaphragm 215 between them can... Figure 2 In terms of the drawing direction, it is from left to right ( Figure 2 The first electrode 212, the second electrode 214, and the diaphragm 215 therebetween are wound in the X direction to form the electrode assembly 210. In the following text, the X direction may be referred to as the winding direction, and the first electrode 212, the second electrode 214, and the diaphragm 215 therebetween are wound in the X direction to form the electrode assembly 210. Figure 2 In terms of the drawing direction, the left and right ends can refer to the front and rear ends of the coil.

[0065] In one or more embodiments, the winding tip may refer to the region at the start of winding during the winding process of the electrode assembly 210, and the winding tail may refer to the region at the end of winding during the winding process of the electrode assembly 210. Accordingly, the first electrode tab 216 at the winding tail may be located on the outer periphery of the wound electrode assembly 210. For example, the winding tail may be located at the outermost edge of the electrode assembly 210.

[0066] The first electrode 212 can be used as a positive electrode (or a positive electrode plate). In one or more embodiments, the first substrate component can be made of, for example, aluminum foil, and, for example, the first active material can include a transition metal oxide.

[0067] The positive electrode plate 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).

[0068] For example, the positive electrode plate may further include additives that can be used as sacrificial positive electrodes.

[0069] Based on a 100wt% positive electrode active material layer, the amount of positive electrode active material can be from about 90wt% to about 99wt%. Based on a 100wt% positive electrode active material layer, the amount of binder and conductive material can be from about 0.5wt% to about 5wt%.

[0070] The binder is used to ensure good adhesion between the positive electrode active material particles and also to ensure good adhesion of the positive electrode active material to the current collector. Non-limiting 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.

[0071] 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 rechargeable lithium batteries) 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, or carbon nanofibers; metallic materials, including copper, nickel, aluminum, silver, etc., in the form of metal powders or metal fibers; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0072] Al can be used as a current collector, but is not limited to this.

[0073] 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.

[0074] The composite oxide can be a lithium transition metal composite oxide. Specific examples of composite oxides may include lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, cobalt-free nickel manganese oxides, or combinations thereof.

[0075] 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); Li a FePO4 (0.90≤a≤1.8).

[0076] 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.

[0077] For example, the positive electrode active material can be a high-nickel positive electrode active material, based on 100 mol% of metals other than lithium in a lithium transition metal composite oxide, with 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 positive electrode active materials can achieve high capacity and can be applied to high-capacity and high-density rechargeable lithium secondary batteries.

[0078] The second electrode 214 can be used as a negative electrode (or negative electrode plate). In one or more embodiments, the second substrate component can be made of, for example, copper foil or nickel foil, and the second active material can include, for example, graphite.

[0079] The negative electrode plate 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 an adhesive and / or a conductive material (e.g., a conductive material).

[0080] For example, the negative electrode active material layer may include from about 90 wt% to about 99.5 wt% of a negative electrode active material, from about 0.5 wt% to about 5 wt% of an adhesive, and from about 0 wt% to about 5 wt% of a conductive material.

[0081] 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.

[0082] The negative electrode active material may include a material that reversibly intercalates / deintercalates lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / de-doping lithium, or a transition metal oxide.

[0083] The material that reversibly intercalates / deintercalates lithium ions may include a carbon-based negative electrode active material, such as, for example, crystalline carbon, amorphous carbon, and / or a combination thereof. 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, mesophase pitch carbide, calcined coke, etc.

[0084] The lithium metal alloy may include 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.

[0085] 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, SiOx (0 < x ≤ 2), a Si-Q alloy (where Q is selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (except 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, SiO2, a Sn-based alloy, or a combination thereof.

[0086] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to an 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 assembled 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 present in an amorphous carbon matrix.

[0087] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core having crystalline carbon and silicon particles, and an amorphous carbon coating on the surface of the core.

[0088] Si-based or Sn-based negative electrode active materials can be used in combination with carbon-based negative electrode active materials.

[0089] According to one or more embodiments, the length of the second electrode 214 may be greater than the length of the first electrode 212 in the direction of the winding axis C of the electrode assembly 210. The upper end of the second electrode 214 may be disposed above the upper end of the first electrode 212, and the lower end of the second electrode 214 may be disposed below the lower end of the second electrode 212.

[0090] The separator 215 can be used to prevent short circuits between the first electrode 212 and the second electrode 214 while allowing lithium ions to move. For example, the separator can be made of, but is not limited to, polyethylene film, polypropylene film, polyethylene-polypropylene film, etc.

[0091] The diaphragm 125 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 double-layer diaphragm, a polyethylene / polypropylene / polyethylene triple-layer diaphragm, a polypropylene / polyethylene / polypropylene triple-layer diaphragm, etc.

[0092] The diaphragm 125 may include a porous substrate and a coating on one or both surfaces of the porous substrate (e.g., two main surfaces), the coating comprising an organic material, an inorganic material, or a combination thereof.

[0093] The porous substrate can be a polymer film formed from any of the following: polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate and polybutylene terephthalate), polyacetal, polyamide, polyimide, polycarbonate, polyetherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fiber, and polytetrafluoroethylene (e.g., Teflon), or copolymers or mixtures of two or more thereof.

[0094] Organic materials may include polyvinylidene fluoride polymers or (meth)acrylic acid polymers.

[0095] 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.

[0096] Organic and inorganic materials can be mixed in a coating, or coatings containing organic materials and coatings containing inorganic materials can be stacked.

[0097] The diaphragm 215 may be longer than the first electrode 212 and the second electrode 214 in the height direction of the electrode assembly 210. For example, in the direction of the winding axis C of the electrode assembly 210, the length of the diaphragm 215 may be greater than the length of the first electrode 212 and the second electrode 214. The upper end of the diaphragm 215 may be disposed above the upper end of the first electrode 212 and the upper end of the second electrode 214, and the lower end of the diaphragm 215 may be disposed below the lower end of the first electrode 212 and the lower end of the second electrode 214.

[0098] Figure 3 This is a cross-sectional view illustrating an example of a secondary battery according to a comparative example of the present disclosure, and Figure 4 This is a cross-sectional view illustrating an example of a secondary battery with an expanded electrode assembly according to a comparative example of the present disclosure.

[0099] refer to Figure 3 and Figure 4 The secondary battery 200 may include an electrode assembly 210, a housing 220, a cover assembly 230, and an insulating gasket 240.

[0100] The cover assembly 230 may include a cover plate 232, an insulating layer 234, a terminal block 236, and an insulating member 238. In one or more embodiments, the cover plate 232 may cover an opening in the housing 220. The cover plate 232 may be coupled to a side surface of the housing 220 corresponding to the side surface of the opening.

[0101] The electrode assembly 210 may include a first electrode 212, a second electrode 214, and a diaphragm 215, and may further include a first electrode connector 216 connected to the first electrode 212 and a second electrode connector 218 connected to the second electrode 214. The first electrode connector 216 may be connected to the cover assembly 230, and the second electrode connector 218 may be connected to the bottom portion of the housing 220.

[0102] Electrode assembly 210 can be formed by winding a first electrode 212, a second electrode 214, and a separator 215 therebetween. Electrode assembly 210 can be wound to form a core and may include through-holes within the core. The dimensions of the first electrode 212 and the second electrode 214 can differ from each other. When the negative electrode is small, the separator may be damaged and a short circuit may occur because lithium ions deposit from the portion of the positive electrode not facing the negative electrode and grow during charging. Accordingly, the size of the second electrode 214, used as the negative electrode, can be larger than the size of the first electrode 212, used as the positive electrode. For example, the length of the second electrode 214 can be greater than the length of the first electrode 212 in the direction of the winding axis of electrode assembly 210 (or in the direction of the winding axis of electrode assembly 210).

[0103] Figure 3 This is an example schematically illustrating the winding structure of the wound electrode assembly 210, but the number and size of the electrode plates can be varied. A first electrode 212 or a second electrode 214 may be present at the outermost edge of the electrode assembly 210. First electrode tabs 216 and second electrode tabs 218 of the electrode assembly 210 may be formed on different side surfaces of the electrode assembly 210.

[0104] refer to Figure 3 The electrode assembly 210 may not contact the side wall portion of the housing 220 before expansion.

[0105] However, due to the mixture of active materials, binders, and conductive materials, the volume of the electrode assembly 210 may change during the charging and discharging of the secondary battery. For example... Figure 4 As illustrated, after the electrode assembly 210 expands, it may come into contact with a sidewall portion of the housing 220 to apply pressure. As a result, the sidewall portion of the housing 220 may exert a reaction pressure on the electrode assembly 210. Accordingly, cracks may appear in the first electrode 212 and the second electrode 214 due to the pressure from the sidewall portion of the housing 220.

[0106] In this disclosure, the contact between the electrode assembly 210 and the housing 220 includes the case where the electrode assembly 210 contacts the housing 220 through another component (such as an insulating component) intervening therebetween, and the case where the electrode assembly 210 directly contacts the housing 220.

[0107] Figure 5 This is an illustration of an example of the shape of a groove region according to one or more embodiments of the present disclosure, and Figure 6 This is a cross-sectional view illustrating an example of a housing having a grooved region formed according to one or more embodiments of the present disclosure.

[0108] refer to Figure 5 and Figure 6 Secondary battery 500 (see) Figure 7 It may include housing 520, cover assembly 510 and electrode assembly 210 (see Figure 2 The secondary battery 500 can be a coin cell or a button cell. For example, the secondary battery 500 can have a cylindrical shape. The housing 520 can accommodate the electrode assembly 210 (see...). Figure 2 It contains an electrolyte and can be used together with the cover assembly 510 to form the external shape of the secondary battery.

[0109] According to one or more embodiments, the housing 520 may include a bottom portion 522, a sidewall portion 524 connected to the bottom portion 522, and an opening portion 526 facing the bottom portion 522. The housing 520 may include a groove region 540 formed on the inner peripheral surface 530 of the sidewall portion 524.

[0110] According to one or more embodiments, the inner peripheral surface 530 may include a first inner peripheral surface 532 positioned adjacent to the opening portion 526 and a second inner peripheral surface 534 positioned adjacent to the bottom portion 522. The groove region 540 may include a first surface 542 connected to the first inner peripheral surface 532, a third surface 546 connected to the second inner peripheral surface 534, and a second surface 544 connected to the first surface 542 and the third surface 546.

[0111] According to one or more embodiments, the first inner circumferential surface 532 and the second inner circumferential surface 534 may be parallel to each other. In one or more embodiments, the second surface 544 may be parallel to the first inner circumferential surface 532 and the second inner circumferential surface 534. However, the second surface 544 may include a surface inclined at a predetermined angle relative to the first inner circumferential surface 532 and / or the second inner circumferential surface 534.

[0112] According to one or more embodiments, the first surface 542 may be perpendicular to the first inner peripheral surface 532, and the third surface 546 may be perpendicular to the second inner peripheral surface 534. As a result, the first surface 542 and the third surface 546 may be parallel to each other. The first surface 542 and the third surface 546 may be perpendicular to the second surface 544.

[0113] According to one or more embodiments, the boundary line 552 between the first inner peripheral surface 532 and the first surface 542 can be formed to be separated from the boundary line 554 between the second inner peripheral surface 534 and the third surface 546 by a predetermined distance d2 (e.g., separated in the winding axis direction of the electrode assembly 210). For example, regarding the winding axis C of the electrode assembly 210 (see... Figure 7 In terms of the direction of the winding axis of the electrode assembly 210 (or the predetermined distance d2 in the direction of the winding axis of the electrode assembly 210), it can be 2 mm to 4 mm. As a result, regarding the winding axis C of the electrode assembly 210 (see...), Figure 7 In terms of the direction of the electrode assembly 210 (or in the direction of the winding axis of the electrode assembly 210), the length of the groove region 540 may correspond to the length of the first electrode 212 used as the positive electrode and / or the second electrode 214 used as the negative electrode.

[0114] According to one or more embodiments, the boundary line 552 between the first inner peripheral surface 532 and the first surface 542 can be positioned at a predetermined distance d1, separating it from the end of the opening portion 526 (e.g., in the direction of the winding axis of the electrode assembly 210), by 0.4 mm to 0.6 mm. As a result, the boundary line 552 between the first inner peripheral surface 532 and the first surface 542 can be formed above the upper end of the first electrode 212 used as a positive electrode and at the same level as the upper end of the second electrode 214 used as a negative electrode. The boundary line 552 between the first inner peripheral surface 532 and the first surface 542 can be formed above the upper end of the first electrode 212 used as a positive electrode and the upper end of the second electrode 214 used as a negative electrode.

[0115] According to one or more embodiments, the boundary line 554 between the second inner peripheral surface 534 and the third surface 546 can be positioned at a predetermined distance d3, separating it from the bottom portion 522 (e.g., in the direction of the winding axis of the electrode assembly 210) by 0.1 mm to 0.3 mm. Consequently, the boundary line 554 between the second outer peripheral surface 534 and the third surface 544 can be formed below the lower end of the first electrode 212 used as a positive electrode and at the same level as the lower end of the second electrode 214 used as a negative electrode. The boundary line 554 between the second inner peripheral surface 534 and the third surface 546 can be formed below the lower ends of both the first electrode 212 used as a positive electrode and the second electrode 214 used as a negative electrode.

[0116] According to one or more embodiments, the distance d4 between the second surface 544 and the boundary line 552 between the first inner peripheral surface 532 and the first surface 542 (e.g., in a direction perpendicular to the winding axis direction of the electrode assembly 210) can be equal to the distance d5 between the second surface 544 and the boundary line 554 between the second inner peripheral surface 534 and the third surface 546 (e.g., in a direction perpendicular to the winding axis direction of the electrode assembly 210).

[0117] According to one or more embodiments, the second surface 544 can be positioned separated from the boundary line 552 between the first inner peripheral surface 532 and the first surface 542 by a predetermined distance d4 of 0.01 mm to 0.07 mm (e.g., separated in a direction perpendicular to the winding axis direction of the electrode assembly 210). As a result, the pressure exerted by the sidewall portion 524 of the housing 520 can be reduced when the electrode assembly expands. However, the shape and size of the groove region 540 can be changed.

[0118] Figure 7 This is a cross-sectional view illustrating an example of a secondary battery having a slotted region according to one or more embodiments of the present disclosure, and Figure 8 This is a cross-sectional view illustrating an example of a secondary battery with an expanded electrode assembly according to one or more embodiments of the present disclosure.

[0119] refer to Figure 7 and Figure 8 The secondary battery 500 may include an electrode assembly 210, a housing 520, a cover assembly 230, and an insulating gasket 240.

[0120] The cover assembly 230 may include a cover plate 232, an insulating layer 234, a terminal plate 236, and an insulating member 238. In one or more embodiments, the cover plate 232 may cover an opening in the housing 220. The cover plate 232 may be coupled to a side surface of the housing 520 corresponding to the side surface of the opening.

[0121] An insertion slot may be formed in the cover plate 232. For example, the insertion slot may be formed at the center of the cover plate 232. A portion of the terminal plate 236 (e.g., the insertion portion 236b of the terminal plate 236) may be inserted into the insertion slot, and the terminal plate 236 may be disposed on the cover plate 232. The terminal plate 236 may include a body portion 236a and an insertion portion 236b protruding from the body portion 236a. In one or more embodiments, the insertion portion 236b of the terminal plate 236 may be inserted into the insertion slot of the cover plate 232. The insertion portion 236b of the terminal plate 236 may be electrically connected by contacting the first electrode tab 216. Reference Figure 7 The cover assembly 230, including the terminal plate 236, can be coupled to the housing 520 such that the insertion portion 236b faces the electrode assembly 210. However, the cover assembly can be coupled to the housing such that the insertion portion of the terminal plate faces the opposite direction to the electrode assembly (e.g., the direction of the upper surface of the battery), but this can be changed.

[0122] An insulating layer 234 may be disposed between the terminal block 236 and the cover plate 232. The insulating layer 234 has adhesive strength and can connect the terminal block 236 and the cover plate 232. The insulating layer 234 may be made of insulating material and can electrically insulate the terminal block 236 and the cover plate 232.

[0123] An insulating member 238 may be disposed on the lower surface of the cover plate 232. In one or more embodiments, the upper surface of the cover plate 232 may face the main body portion 236a of the terminal plate 236, and the lower surface of the cover plate 232 may face the electrode assembly 210. The insulating member 238 may be made of an insulating material and may electrically insulate the cover plate 232 from the electrode assembly 210, or may electrically insulate the cover plate 232 from the first electrode terminal piece 216.

[0124] Electrode assembly 210 may include a terminating strip that wraps around at least a portion of the circumference of the outermost edge of electrode assembly 210. In one or more embodiments, the terminating strip may secure the wound electrode assembly 210. For example, in electrode assembly 210, the winding of the first electrode 212, the second electrode 214, and the diaphragm 215 may be held in place by the terminating strip without unwinding. For example, the terminating strip may have adhesive strength and may be coupled to at least a portion of the circumference of the outermost edge of electrode assembly 210.

[0125] The electrode assembly 210 may further include a first electrode tab 216 connected to the first electrode 212 and a second electrode tab 218 connected to the second electrode 214. The first electrode tab 216 may be connected to the cover assembly 230, and the second electrode tab 218 may be connected to the bottom portion 522 of the housing 520.

[0126] The first electrode tab 216 can be bent within a housing 520 below a terminal plate 236, which houses the electrode assembly 210 and is coupled to a cover assembly 230. A short circuit between the bent first electrode tab 216 and the electrode assembly 210 can be prevented by an insulating washer 240. For example, the insulating washer 240 can be disposed between the electrode assembly 210 and the terminal plate 236. For example, the insulating washer 240 can be disposed between the first electrode tab 216 and the electrode assembly 210 located below the terminal plate 236. The insulating washer 240 can contain insulating material. The insulating washer 240 can separate the first electrode tab 216 and the electrode assembly 210. The insulating washer 240 can electrically insulate the first electrode tab 216 and the electrode assembly 210.

[0127] Each of the first electrode terminal piece 216 and the second electrode terminal piece 218 can be covered by a covering tape. The covering tape may contain an insulating material. In one or more embodiments, the insulating material may have electrical insulating properties, thus preventing current from flowing through. As a result, short circuits that may occur between the first electrode terminal piece 216, the second electrode terminal piece 218, and the conductive components can be prevented.

[0128] The electrode assembly 210 can be housed in the housing 520 together with the electrolyte in a cylindrical shape. The electrolyte can be an organic liquid containing added salts to allow lithium ions to move between the positive and negative electrode plates. The electrolyte can contain, but is not limited to, a non-aqueous organic electrolyte, which is a mixture of lithium salts such as LiPF6, LiPF4, or LiClO4 and a high-purity organic solvent.

[0129] According to one or more embodiments, the housing 520 may include a groove region 540 formed on the inner peripheral surface 530 of the sidewall portion 524. The length of the groove region 540 can be set with respect to the lengths of the first electrode 212 and / or the second electrode 214 in the direction of the winding axis C of the electrode assembly 210. For example, the first electrode 212 may be a positive electrode, and the second electrode 214 may be a negative electrode. Since the negative electrode contains a negative electrode active material such as silicon, it can expand more than the positive electrode during the charging and discharging of the secondary battery. Accordingly, the length of the groove region 540 can be set to correspond to the length of the second electrode 214 as the negative electrode in the direction of the winding axis of the electrode assembly 210.

[0130] According to one or more embodiments, the boundary line 552 between the first inner peripheral surface 532 and the first surface 542 can be formed to be separated from the boundary line 554 between the second inner peripheral surface 534 and the third surface 546 by a predetermined distance d2 (e.g., separated in the direction of the winding axis of the electrode assembly 210). This predetermined distance d2, in the direction of the winding axis C of the electrode assembly 210 (or in the direction of the winding axis of the electrode assembly 210), can correspond to the length of the second electrode 214. For example, the predetermined distance d2, in the direction of the winding axis C of the electrode assembly 210 (or in the direction of the winding axis of the electrode assembly 210), can be equal to the length of the second electrode 214. As a result, when the electrode assembly 210 expands, the pressure exerted by the sidewall portion 524 of the housing 520 is reduced, thus preventing cracks in the first electrode 212 and the second electrode 214 in advance. However, this predetermined distance can be greater than or less than the length of the second electrode 214.

[0131] According to one or more embodiments, the boundary line 552 between the first inner peripheral surface 532 and the first surface 542 can be positioned corresponding to the upper end of the second electrode 214, and the boundary line 554 between the second inner peripheral surface 534 and the third surface 546 can be positioned corresponding to the lower end of the second electrode 214. For example, the boundary line 552 between the first inner peripheral surface 532 and the first surface 542 can be formed at the same level as the upper end of the wound second electrode 214, or it can be formed above the upper end of the wound second electrode 214. The boundary line 554 between the second inner peripheral surface 534 and the third surface 546 can be formed at the same level as the lower end of the wound second electrode 214, or it can be formed below the lower end of the wound second electrode 214. Due to these structural features, the electrode assembly 210 can be fixed during expansion via the boundary line 552 between the first inner circumferential surface 532 and the first surface 542, and the boundary line 554 between the second inner circumferential surface 534 and the third surface 546. As a result, since the electrode assembly 210 is fixed via the groove region 540 during movement of the secondary battery 500, movement of the electrode assembly 210 within the secondary battery 500 can be reduced.

[0132] Figure 9 This is an illustration of an example of the shape of a groove region according to one or more embodiments of the present disclosure, and Figure 10 This is a cross-sectional view illustrating an example of a secondary battery having a groove region according to one or more embodiments of the present disclosure. Figure 9 and Figure 10 The configuration already includes Figures 5 to 8 The description of the configuration described in the document has been omitted.

[0133] According to one or more embodiments, the first surface 942 may include an inclined surface, and the third surface 946 may include an inclined surface. Figure 9 and Figure 10 As illustrated, the boundary line 952 between the first inner peripheral surface 932 and the first surface 942 can be formed above the boundary line between the first surface 942 and the second surface 944. The boundary line 954 between the second inner peripheral surface 934 and the third surface 946 can be formed below the boundary line between the second surface 944 and the third surface 946. However, unlike... Figure 9 and Figure 10 In the illustrated case, the boundary line 952 between the first inner peripheral surface 932 and the first surface 942 can be formed below the boundary line between the first surface 942 and the second surface 944. The boundary line 954 between the second inner peripheral surface 934 and the third surface 946 can be formed above the boundary line between the second surface 944 and the third surface 946.

[0134] like Figure 10 As illustrated, the boundary line between the first surface 942 and the second surface 944 can be formed above the upper end of the wound first electrode 212, and the boundary line between the second surface 944 and the third surface 946 can be formed below the lower end of the wound first electrode 212. Unlike... Figure 10 In the illustrated case, the boundary line between the first surface 942 and the second surface 944 can be formed below the upper end of the wound first electrode 212, and the boundary line between the second surface 944 and the third surface 946 can be formed above the lower end of the wound first electrode 212.

[0135] Figure 11 This is an illustration of an example of the shape of a groove region according to one or more embodiments of the present disclosure, and Figure 12 This is a cross-sectional view illustrating an example of a secondary battery having a groove region according to one or more embodiments of the present disclosure. Figure 11 and Figure 12 The configuration already includes Figures 5 to 8 The description of the configuration described in the document has been omitted.

[0136] According to one or more embodiments, the first inner circumferential surface 1132 may include a curved surface, and the third surface 1146 may include a curved surface. Figure 11 and Figure 12 As illustrated, the boundary line 1152 between the first inner peripheral surface 1132 and the first surface 1142 can be formed above the boundary line between the first surface 1142 and the second surface 1144. The boundary line 1154 between the second inner peripheral surface 1134 and the third surface 1146 can be formed below the boundary line between the second surface 1144 and the third surface 1146. However, the shape of the groove region 1140 is not limited to this and differs from... Figure 11 and Figure 12 In the illustrated case, the boundary line 1152 between the first inner peripheral surface 1132 and the first surface 1142 can be formed below the boundary line between the first surface 1142 and the second surface 1144. The boundary line 1154 between the second inner peripheral surface 1134 and the third surface 1146 can be formed above the boundary line between the second surface 1144 and the third surface 1146.

[0137] like Figure 12 As illustrated, the boundary line between the first surface 1142 and the second surface 1144 can be formed above the upper end of the wound first electrode 212, and the boundary line between the second surface 1144 and the third surface 1146 can be formed below the lower end of the wound first electrode 212. Unlike... Figure 12 In the illustrated case, the boundary line between the first surface 1142 and the second surface 1144 can be formed below the upper end of the wound first electrode 212, and the boundary line between the second surface 1144 and the third surface 1146 can be formed above the lower end of the wound first electrode 212.

[0138] The positive and negative electrodes may comprise a mixture of active materials, binders, and conductive materials. The volume of the electrode assembly may change during charging and discharging due to the chemicals that form the positive and negative electrodes. The chemicals forming the positive and negative electrodes expand, and therefore, the electrode assembly may come into contact with the housing containing the electrode assembly. At this point, the housing may exert pressure on the electrode assembly, and thus, the positive and negative electrodes of the electrode assembly may be damaged.

[0139] According to one or more embodiments of this disclosure, a secondary battery can be provided to improve the safety of the secondary battery.

[0140] According to one or more embodiments of this disclosure, a secondary battery can be provided to improve the performance and safety of the secondary battery by reducing the pressure applied to the electrode components in the secondary battery.

[0141] According to one or more embodiments of this disclosure, when the electrode assembly expands due to the charging and discharging of the secondary battery, the pressure applied to the electrode assembly can be reduced by ensuring free space through the groove area of ​​the housing, thus preventing damage to the electrode in advance.

[0142] According to one or more embodiments of this disclosure, when the electrode assembly expands due to the charging and discharging of the secondary battery, the groove area of ​​the housing can fix the electrode assembly even if the secondary battery moves, thereby reducing the movement of the electrode assembly within the secondary battery.

[0143] While this disclosure has been described above with reference to embodiments thereof, it is not limited thereto. Those skilled in the art can make various modifications and variations thereto within the spirit and equivalent scope of the claims.

[0144] Example embodiments have been disclosed herein. While specific terminology has been used, it is used and interpreted in a general and descriptive sense only and not for limiting purposes. In some cases, as will be apparent to those skilled in the art at the time of filing this application, unless otherwise specifically stated, features, characteristics, and / or elements described in connection with particular embodiments may be used alone or in combination with features, characteristics, and / or elements described in connection with other embodiments. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope set forth in the following claims.

[0145] Explanation of reference numerals in the attached figures

[0146] 100, 200, 500, 900, 1100: Secondary batteries

[0147] 110, 230, 510, 910, 1110: Cover assembly

[0148] 120, 220, 520, 920, 1120: Shell

[0149] 210: Electrode assembly

[0150] 212: First electrode

[0151] 214: Second electrode

[0152] 215: Diaphragm

[0153] 216: First electrode connector

[0154] 218: Second electrode connector

[0155] 522: Bottom part

[0156] 524: Sidewall section

[0157] 526: Opening portion

[0158] 530, 930, 1130: Inner peripheral surface

[0159] 532, 932, 1132: First inner circumferential surface

[0160] 534, 934, 1134: Second inner circumferential surface

[0161] 540, 940, 1140: Tank area

[0162] 542, 942, 1142: First surface

[0163] 544, 944, 1144: Second Surface

[0164] 546, 946, 1146: Third Surface

[0165] 552, 952, 1152: Boundary lines between the first inner circumferential surface and the first surface

[0166] 554, 954, 1154: Boundary lines between the second inner circumferential surface and the third surface.

Claims

1. A secondary battery, comprising: An electrode assembly, comprising a first electrode, a second electrode, and a diaphragm therebetween; The housing includes a bottom portion, a sidewall portion connected to the bottom portion, and an opening portion facing the bottom portion, the housing accommodating an electrode assembly; as well as A cover assembly, attached to one end of the sidewall portion of the housing, to seal the opening. The housing includes a groove region on the inner circumferential surface of the sidewall portion.

2. The secondary battery according to claim 1, wherein: The first electrode is a positive electrode, and The second electrode is the negative electrode.

3. The secondary battery according to claim 1, wherein the length of the second electrode is greater than the length of the first electrode in the winding axis direction of the electrode assembly.

4. The secondary battery according to claim 1, wherein the secondary battery comprises a coin cell battery or a button cell battery.

5. The secondary battery according to claim 1, wherein the material of the casing includes stainless steel.

6. The secondary battery according to claim 1, wherein: The electrode assembly further includes: The first electrode terminal is connected to the first electrode, and The second electrode connector is connected to the second electrode.

7. The secondary battery of claim 6, wherein the first electrode terminal is connected to the cover assembly.

8. The secondary battery according to claim 6, wherein the second electrode terminal is connected to the bottom portion of the housing.

9. The secondary battery according to claim 1, wherein: The inner peripheral surface includes: The first inner circumferential surface is positioned adjacent to the opening portion, and The second inner circumferential surface is positioned adjacent to the bottom portion, and The groove region includes: The first surface is connected to the first inner peripheral surface. The third surface is connected to the second inner peripheral surface, and The second surface is connected to the first surface and the third surface.

10. The secondary battery according to claim 9, wherein: The third surface is perpendicular to the second inner circumferential surface.

11. The secondary battery according to claim 9, wherein: The first surface includes an inclined surface, and The third surface includes an inclined surface.

12. The secondary battery according to claim 9, wherein: The first surface includes a curved surface, and The third surface includes a curved surface.

13. The secondary battery according to claim 9, wherein: The first boundary line between the first inner circumferential surface and the first surface corresponds to the upper end of the second electrode, and The second boundary line between the second inner circumferential surface and the third surface corresponds to the lower end of the second electrode.

14. The secondary battery according to claim 9, wherein the boundary line between the first inner circumferential surface and the first surface is separated from the end of the opening portion by a predetermined distance of 0.4 mm to 0.6 mm in the winding axis direction of the electrode assembly.

15. The secondary battery of claim 9, wherein the boundary line between the second inner circumferential surface and the third surface is positioned at a predetermined distance of 0.1 mm to 0.3 mm from the bottom portion in the direction of the winding axis of the electrode assembly.

16. The secondary battery of claim 9, wherein the distance between the boundary line between the second surface and the first inner peripheral surface and the first surface in a direction perpendicular to the winding axis direction of the electrode assembly is equal to the distance between the boundary line between the second surface and the second inner peripheral surface and the third surface in the direction perpendicular to the winding axis direction of the electrode assembly.

17. The secondary battery of claim 9, wherein the boundary line between the second surface and the first inner peripheral surface and the first surface is separated by a predetermined distance of 0.01 mm to 0.07 mm in a direction perpendicular to the winding axis direction of the electrode assembly.

18. The secondary battery of claim 9, wherein the first boundary line between the first inner peripheral surface and the first surface and the second boundary line between the second inner peripheral surface and the third surface are separated by a predetermined distance in the winding axis direction of the electrode assembly.

19. The secondary battery according to claim 18, wherein the predetermined distance corresponds to the length of the second electrode.

20. The secondary battery according to claim 18, wherein the predetermined distance is 2 mm to 4 mm.

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