Electrode assembly and rechargeable battery including the same

Abstract

An electrode assembly and a battery including the same are disclosed. One embodiment is an electrode assembly formed by winding a laminate, in which a separator is interposed between a positive plate and a negative plate, multiple times to have a winding center, wherein the cutting shape at the winding end of the separator has a shape in which the upper end is removed.

Description

Technology Field

[0001] The present disclosure relates to an electrode assembly and a battery comprising the same. Background Technology

[0002] Unlike primary batteries, which cannot be recharged, secondary batteries are batteries capable of charging and discharging. Low-capacity secondary batteries (hereinafter also simply referred to as "batteries") are used in small portable electronic devices such as smartphones, feature phones, laptop computers, digital cameras, and camcorders, while high-capacity batteries are widely used as power sources for motor driving and power storage in hybrid and electric vehicles. Such batteries include electrodes comprising a positive electrode and / or a negative electrode, an electrode assembly comprising the electrodes, a case housing the same, and electrode terminals connected to the electrode assembly.

[0003] As technology advances, there is a growing demand for high-capacity batteries. Accordingly, multiple batteries may be electrically connected and used. For example, batteries may be applied to electronic devices in the form of a battery module comprising multiple batteries and / or a battery pack comprising multiple battery modules. Depending on the embodiment, a battery pack may be composed of multiple batteries. In this case, the electronic device is one that requires high power and / or high capacity, such as an electric vehicle.

[0004] A battery includes an electrode assembly that functions as a unit structure for performing charging and discharging operations. The electrode assembly has a structure in which a separator is interposed between a positive plate and a negative plate. Unlike positive or negative plates containing a metal substrate, the separator, formed from a polymer or the like, is prone to shrinking in high-temperature environments. Considering this, the separator is typically manufactured to be larger than the positive or negative plate, and the portion larger than the positive or negative plate is called the overhang portion. Due to the overhang portion, it is possible to prevent the positive and negative plates from coming into contact even if the separator shrinks to some extent.

[0005] Coin batteries typically include a jelly-roll type electrode assembly. The jelly-roll type electrode assembly can be formed by winding a laminate of a sheet-shaped positive plate, separator, negative plate, and separator, which is relatively long compared to its width, multiple times in a clockwise or counterclockwise direction. A coin battery can be manufactured by inserting the jelly-roll type electrode assembly into a can with an open top, placing a cap assembly on the top of the can, and joining them by means such as welding. In the jelly-roll type electrode assembly as well, the separator is larger than the positive plate or negative plate and has an overhang portion.

[0006] However, when a cap assembly is placed on top of a can into which a jelly-roll type electrode assembly is inserted and the joint surface is welded, the overhang portion of the separator may interfere with the cap assembly. As a result, pressure is applied to the separator, which may damage the separator or cause defects such as pinholes at the joint surface between the can and the cap assembly.

[0007] The information described above disclosed in the background technology of this invention is intended only to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art. The problem to be solved

[0008] The problem that the present disclosure aims to solve is to provide a jellyroll-type electrode assembly capable of preventing interference between the overhang portion of the separator and the cap assembly, and a battery including the same.

[0009] However, the technical problems that the present disclosure aims to solve are not limited to those described above, and other unmentioned problems can be clearly understood by those skilled in the art from the description of the invention below. means of solving the problem

[0010] One embodiment of the present disclosure for solving the above technical problem is an electrode assembly formed by winding a laminate, in which a separator is interposed between an anode plate and a cathode plate, multiple times to have a winding center, wherein the cutting shape at the winding end of the separator may have a shape in which the upper end is removed.

[0011] According to one aspect of the above embodiment, the cutting shape may have a shape in which the upper portion of the separator is removed in a curved manner.

[0012] According to another aspect of the above embodiment, the cutting shape may have a shape in which the upper portion of the separator is removed in a straight line. For example, the cutting shape may have a shape in which the corner portion is removed only at the top.

[0013] According to another aspect of the above embodiment, the cutting shape may have a shape in which the lower end of the wound end of the separator is also removed. For example, the cutting shape may have a shape that is vertically symmetrical with respect to the width direction of the separator. In this case, the cutting shape may have a shape in which the central part is more convex than the top and bottom with respect to the width direction of the separator.

[0014] For example, the cutting shape may have a shape in which the upper and lower portions of the separator are each removed in a curved manner. Alternatively, the cutting shape may have a shape in which the upper and lower portions of the separator are each removed in a straight line. In this case, the cutting shape may have a shape in which the corner portions are removed from the top and bottom, respectively.

[0015] Another embodiment of the present disclosure for solving the above technical problem is an electrode assembly formed by winding a laminate, in which a separator is interposed between an anode plate and a cathode plate, multiple times to have a winding center, wherein the separator has an overhang portion in the longitudinal direction with respect to the anode plate and the cathode plate, and the width of the upper portion of the overhang portion may be smaller than the width of the central portion.

[0016] According to one aspect of the above embodiment, the widthwise boundary of the overhang portion may have a curved cutting shape around the top.

[0017] According to another aspect of the above embodiment, the widthwise boundary of the overhang portion may have a straight cutting shape around the top. For example, the overhang portion may have a shape in which the corner portion is removed only at the top of the central portion.

[0018] According to another aspect of the above embodiment, the width of the bottom of the overhang portion may also be smaller than the central portion. For example, the widthwise boundary of the overhang portion may have a cutting shape that is vertically symmetrical with respect to the width direction of the separator. In this case, the widthwise boundary of the overhang portion may have a cutting shape with a curve in which the central portion is more convex than the upper and lower portions with respect to the width direction of the separator.

[0019] Alternatively, the widthwise boundary of the overhang portion may have a straight cutting shape in which the central part is more convex than the upper and lower parts relative to the width direction of the separator. For example, the overhang portion may have a shape in which the corner portions are removed at the top and bottom, respectively.

[0020] A battery according to one embodiment of the present disclosure for solving the above technical problem comprises a can having a cylindrical shape and an opening having an open top, an electrode assembly formed by winding a laminate having a winding center multiple times, wherein a separator is interposed between a positive plate and a negative plate, and a cap assembly joined to the top of the can to cover the opening, wherein the cutting shape at the end of the winding of the separator may have a shape in which the top is removed. Effects of the invention

[0021] According to an embodiment of the present disclosure, when a jelly roll-type electrode assembly is housed inside a can and a cap assembly is placed on top of it and joined, interference caused by the overhang portion of the separator does not occur, thereby preventing damage to the separator or the occurrence of pinholes, etc., on the joint surface between the can and the cap assembly.

[0022] However, the effects obtainable through the present invention are not limited to those described above, and other unmentioned technical effects will be clearly understood by those skilled in the art from the description of the invention below. Brief explanation of the drawing

[0023] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1 is a perspective view schematically showing the configuration of a coin-type battery according to one embodiment. Figure 2 is a schematic cross-sectional view taken along line II-II of Figure 1. FIG. 3 is a front view schematically showing the configuration of a conventional jelly roll type electrode assembly. FIG. 4 is a front view schematically showing the configuration of an electrode assembly according to one embodiment. FIG. 5 is a front view schematically showing the configuration of an electrode assembly according to another embodiment. FIG. 6 is a front view schematically showing the configuration of an electrode assembly according to another embodiment. FIG. 7 is a front view schematically showing the configuration of an electrode assembly according to another embodiment. Specific details for implementing the invention

[0024] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings. Instead, based on the principle that the inventor may appropriately define the concepts of terms to best describe his invention, they should be interpreted in a meaning and concept consistent with the technical spirit of the present invention. Therefore, it should be understood that the embodiments described in this specification and the configurations illustrated in the drawings are merely some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention; thus, various equivalents and modifications that can replace them may exist at the time of filing this application. Furthermore, as used in this specification, "comprise" or "include" and / or "comprising" or "including" specify the presence of the mentioned features, numbers, steps, actions, parts, elements, and / or groups thereof, and do not exclude the presence or addition of one or more other features, numbers, actions, parts, elements, and / or groups. Additionally, when describing embodiments of the present invention, "can" or "can be" may include "one or more embodiments of the present invention."

[0025] Additionally, to aid in understanding the invention, the attached drawings are not drawn to actual scale, and the dimensions of some components may be exaggerated. Furthermore, the same reference numerals may be assigned to identical components in different embodiments.

[0026] The statement that two subjects of comparison are 'identical' means that they are 'substantially identical.' Therefore, substantial identity may include deviations considered low in the industry, for example, deviations within 5%. Additionally, the statement that a parameter is uniform in a given area may mean that it is uniform from an average perspective.

[0027] Although terms such as "first," "second," etc., are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless specifically stated otherwise, the first component may also be the second component.

[0028] Throughout the specification, unless specifically stated otherwise, each component may be singular or plural.

[0029] The fact that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0030] Furthermore, where it is stated that one component is "connected," "coupled," or "connected" to another component, it should be understood that while said components may be directly connected or connected to each other, another component may be "interposed" between each component, or that each component may be "connected," "coupled," or "connected" through another component. Additionally, when it is stated that a part is electrically coupled with another part, this includes not only cases where they are directly connected but also cases where they are connected with another component in between.

[0031] Throughout the specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise. That is, "and / or" includes any combination or any combination of the enumerated items. "C to D" means C or more and D or less, unless specifically stated otherwise.

[0032] When syntax 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" is used to specify a list of elements A, B, and C, the syntax can refer to any suitable combination.

[0033] The term "use" may be considered synonymous with the term "utilize." As used herein, "substantially," "about," and similar terms are used as terms of approximation rather than degree, and are intended to account for the inherent variation of measured or calculated values ​​that a person skilled in the art would recognize.

[0034] In this specification, terms such as first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Accordingly, the first element, component, region, layer, or section discussed below may be named the second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0035] Spatial relative terms such as "beneath," "below," "lower," "above," and "upper" may be used herein for ease of explanation to describe the relationship between one element or feature and another element(s) or feature(s) as illustrated in the drawings. Spatially relative positions are to be understood as encompassing different orientations of the device in use or operation, in addition to the orientations depicted in the figures. For example, if the device in the drawing is inverted, an element described as "below" or "below" is understood as "above" or "upper" of another element. Thus, the term "below" may encompass both the up and down directions.

[0036] The terms used in this specification are intended to describe embodiments of the present disclosure and are not intended to limit the present disclosure.

[0037] Hereinafter, a secondary battery and a battery pack including the same according to various embodiments of the present invention will be described with reference to the attached drawings. In this process, the thickness of lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of explanation. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intention or convention of the user or operator. Therefore, the definitions of these terms should be based on the content throughout this specification.

[0038] FIG. 1 is a perspective view schematically showing the configuration of a battery according to one embodiment. FIG. 2 is a schematic cross-sectional view taken along line II-II of FIG. 1. Referring to FIG. 1 and FIG. 2, the battery (1) includes an electrode assembly (100), a can (200), and a cap assembly (300).

[0039] A battery (1) according to one embodiment may be a coin-type battery or a button-type battery. However, it is not limited thereto, and the battery (1) may be a cylindrical battery or a prismatic battery.

[0040] A coin-type battery refers to a battery in the shape of a thin coin or button, and may refer to a battery in which the ratio of height to diameter is relatively small. For example, the ratio of a coin-type battery may be 1 or less, but is not limited thereto. Also, the horizontal cross-section of a coin-type battery may be circular, but this is also exemplary. For example, the horizontal cross-section of a coin-type battery may be polygonal or elliptical.

[0041] The can (100) forms the general exterior of the battery (1) and can accommodate an electrode assembly (200) inside. The can (100) can be formed from a material that is rigid and has excellent heat transfer properties. For example, the can (100) can be formed from a material including at least one of steel, stainless steel, aluminum, and aluminum alloy. Accordingly, the can (100) can protect the electrode assembly (200) from external impact and perform a heat dissipation function to release heat associated with the charging and discharging operation of the electrode assembly (200) to the outside.

[0042] The can (100) may also be formed of an electrically conductive metal material. Accordingly, the can (100) or the cap plate (310) of the cap assembly (300) connected thereto may function as a terminal of the battery (1).

[0043] The can (100) may include a bottom portion (110) and a side wall portion (120). The bottom portion (110) may form the lower exterior of the can (100). The bottom portion (110) may be formed to have a shape approximately like a disc.

[0044] The side wall portion (120) can form the periphery of the can (100). The side wall portion (120) may have a cylindrical shape extending upward from the edge of the bottom portion (110). The side wall portion (120) may be positioned to surround the upper space of the bottom portion (110). The side wall portion (120) may have a planar shape corresponding to the shape of the bottom portion (110), for example, a circular cross-sectional shape in the horizontal direction.

[0045] The perimeter surface of the bottom portion (120) can be joined to the lower portion of the side wall portion (110). The bottom portion (120) can be formed integrally with the side wall portion (110) by a drawing process or the like, or alternatively, it is also possible to manufacture it separately from the side wall portion (110) and then join it to the side wall portion (110) by welding or the like.

[0046] The can (100) may further include an opening (130) that opens the upper portion of the side wall portion (110). The opening (130) may function as a configuration that provides a path for the electrode assembly (200), described later, to be inserted into the interior of the can (100) in the upper region of the can (100), and provides a space for the cap assembly (300), described later, to be installed. The opening (130) may refer to an empty space surrounded by the upper portion of the side wall portion (110) located on the opposite side of the bottom portion (120).

[0047] The electrode assembly (200) can function as a unit structure that performs charging and discharging operations of power in the battery (1). The electrode assembly (200) may include a first electrode plate (210), a second electrode plate (220), and a separator (230) disposed between the first electrode plate (210) and the second electrode plate (220).

[0048] The electrode assembly (200) can be placed inside the can (100). The electrode assembly (200) can be inserted into the interior of the case (100) through the opening (130) of the can (100).

[0049] The electrode assembly (200) may have a circular shape wound around a winding axis. More specifically, the electrode assembly (200) may have a shape in which a first electrode plate (210), a separator (230), a second electrode plate (220), and a separator (230) are stacked and wound multiple times along a clockwise or counterclockwise direction around a winding axis. Accordingly, the electrode assembly (200) may have a shape approximately like a jelly roll (cylindrical). Here, the winding axis may refer to a straight line penetrating the center of the electrode assembly (200). The separator (230) has an overhang portion that is larger in size than the first electrode plate (210) and the second electrode plate (220).

[0050] The first electrode plate (210) can function as the positive electrode of the electrode assembly (200). The first electrode plate (210) may be formed to have the form of a foil containing a metal material such as aluminum or an aluminum alloy. The type, size, and shape of the first electrode plate (210) are not particularly limited, as long as it is conductive without causing chemical changes in the battery.

[0051] A first active material layer may be applied to at least a portion of the first electrode plate (210). The first active material layer may be applied to both sides of the first electrode plate (210), or alternatively, it may be applied to only one side of the first electrode plate (210). As the first electrode plate (210) functions as an anode, the first active material layer may include an anode active material.

[0052] The cathode active material may be a compound capable of reversible intercalation and deintercalation of lithium (a lithated intercalation compound). More specifically, one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, iron, and combinations thereof may be used.

[0053] For example, the positive electrode active material may include at least one of lithium-iron-phosphorus oxide (LiFePO4, LFP), lithium-manganese-iron-phosphorus oxide (LiMnFePO4, LMFP), and lithium-nickel-cobalt-manganese oxide (LiNixCoyMnzO2, NCM). Here, 0 <x<1, 0<y<1, 0<z<1, x+y+z=1을 만족할 수 있다. 양극 활물질은 리튬-철-인 산화물(LiFePO4, LFP), 리튬-망간-철-인 산화물(LiMnFePO4, LMFP), 리튬-니켈-코발트-망간 산화물(LiNixCoyMnzO2, LNCM) 중 어느 하나만을 포함할 수 있고, 리튬-철-인 산화물(LiFePO4, LFP), 리튬-망간-철-인 산화물(LiMnFePO4, LMFP), 리튬-니켈-코발트-망간 산화물(LiNixCoyMnzO2, LNCM)중 어느 두개 또는 이들을 모두 포함하는 것도 가능하다.

[0054] The first active material layer may further include an anode conductive material. The anode conductive material is used to impart conductivity to the first active material layer, and any electronically conductive material that does not cause chemical changes can be used. Examples of anode conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjenblack, carbon fiber, carbon nanofiber, carbon nanotube, etc., metal-based materials in the form of metal powder or metal fibers containing copper, nickel, aluminum, silver, etc., or conductive polymers such as polyphenylene derivatives, or mixtures thereof.

[0055] The first active material layer may further include an anode binder. The anode binder serves to adhere the particles constituting the anode active material well to each other and also to adhere the anode active material well to the first electrode plate (210). Examples of anode binders may include non-aqueous binders, aqueous binders, dry binders, or combinations thereof.

[0056] Examples of non-aqueous binders include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide imide, polyimide, or combinations thereof.

[0057] The water-based binder may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylenepropylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0058] When using a water-based binder as the anode binder, it may further include a cellulose-based compound capable of imparting viscosity. As this cellulose-based compound, one or more types such as carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or alkali metal salts thereof may be used in a mixture. Na, K, or Li may be used as the alkali metal.

[0059] The dry binder is a polymer material capable of fiberization, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0060] The first electrode plate (210) can be electrically connected to the cap assembly (300), more specifically to the terminal plate (320). As the first electrode plate (210) functions as the positive electrode of the electrode assembly (200), the terminal plate (320) of the cap assembly (300) can function as the positive terminal of the battery (1). For example, the first electrode plate (210) can be electrically connected to the terminal plate (320) by a first electrode tab (240). The first electrode tab (240) can be formed of a conductive metal material such as copper, a copper alloy, nickel, or a nickel alloy. The first electrode tab (240) is positioned on the upper side of the electrode assembly (200), and both ends can be connected to the first electrode plate (210) and the terminal plate (320), respectively. One end of the first electrode tab (240) can be directly connected to the first electrode plate (210). However, the first electrode plate (210) may also be directly connected to the terminal plate (320) without the first electrode tab (240).

[0061] The second electrode plate (220) can function as the negative electrode of the electrode assembly (200). The second electrode plate (220) may be formed to have the shape of a foil containing a metal material such as copper, a copper alloy, nickel, or a nickel alloy. The second electrode plate (220) may be positioned facing the first electrode plate (210) at a predetermined distance apart. The type, size, and shape of the second electrode plate (220) are not particularly limited, as long as it is conductive without causing chemical changes in the battery.

[0062] A second active material layer may be applied to at least a portion of the second electrode plate (220). The second active material layer may be applied to both sides of the second electrode plate (220), or alternatively, it may be applied to only one side of the second electrode plate (220). As the second electrode plate (220) functions as a negative electrode, the second active material layer may include a negative electrode active material.

[0063] The negative electrode active material may include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0064] Materials capable of reversibly intercalating / deintercalating lithium ions may include carbon-based negative electrode active materials, such as crystalline carbon, amorphous carbon, or a combination thereof. Examples of crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, and examples of amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0065] As lithium metal alloys, alloys of lithium and metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn can be used.

[0066] Si-based negative electrode active materials or Sn-based negative electrode active materials may be used as materials capable of doping and undoping lithium. Si-based negative electrode active materials may be silicon, silicon-carbon composites, SiOx (x = 1 or 2), Si-Q alloys (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), or combinations thereof. Sn-based negative electrode active materials may be Sn, SnO2, Sn-based alloys, or combinations thereof.

[0067] A 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, it may include a secondary particle (core) assembled from silicon primary particles and an amorphous carbon coating layer (shell) located on the surface of the secondary particle. Amorphous carbon may also be located between the silicon primary particles, so that, for example, the silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0068] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core containing crystalline carbon and silicon particles and an amorphous carbon coating layer located on the surface of the core.

[0069] Si-based or Sn-based cathode active materials can be used in combination with carbon-based cathode active materials.

[0070] The second active material layer may further include a cathode conductive material and a cathode binder.

[0071] The cathode conductive material is used to impart conductivity to the second active material layer, and any electronically conductive material that does not cause chemical changes can be used. Examples of cathode conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc., metal-based materials in the form of metal powder or metal fibers containing copper, nickel, aluminum, silver, etc., or conductive polymers such as polyphenylene derivatives, or mixtures thereof.

[0072] The negative electrode binder serves to adhere the particles constituting the negative electrode active material to each other well, and also to adhere the negative electrode active material well to the second electrode plate (220). Examples of negative electrode binders may include non-aqueous binders, aqueous binders, dry binders, or combinations thereof.

[0073] Examples of non-aqueous binders include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide imide, polyimide, or combinations thereof.

[0074] The water-based binder may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylenepropylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0075] When using a water-based binder as the cathode binder, a cellulose-based compound capable of imparting viscosity may be further included. As this cellulose-based compound, one or more types such as carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or alkali metal salts thereof may be used in a mixture. Na, K, or Li may be used as the alkali metal.

[0076] The dry binder is a polymer material capable of fiberization, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0077] The second electrode plate (220) can be electrically connected to the can (100). For example, the second electrode plate (220) can be electrically connected to the can (100) by the second electrode tab (250). As the second electrode plate (220) functions as the negative electrode of the electrode assembly (200), the can (200) can function as the negative terminal of the battery (1). The second electrode tab (250) can be formed from a conductive metal material such as copper, a copper alloy, nickel, or a nickel alloy. The second electrode tab (250) is positioned on the lower side of the electrode assembly (200), and both ends can be connected to the second electrode plate (220) and the bottom portion (110) of the can (100), respectively. One end of the second electrode tab (250) can be directly connected to the second electrode plate (220). However, the second electrode plate (220) can also be directly connected to the can (100) without the second electrode tab (250).

[0078] A separator (230) may be placed between the first electrode plate (210) and the second electrode plate (220). The separator (230) may perform the function of preventing a short circuit between the first electrode plate (210) and the second electrode plate (220) while allowing the movement of lithium ions between the first electrode plate (210) and the second electrode plate (220).

[0079] As such a separator (230), polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer membrane of two or more layers thereof may be used, and a mixed multilayer membrane such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator may be used.

[0080] The separator (230) may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0081] The porous substrate may be a polymer membrane formed from any one 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 oxide; cyclic olefin copolymer; polyphenylene sulfide; polyethylene naphthalate; glass fiber; Teflon; and polytetrafluoroethylene, or a copolymer or mixture of two or more of these.

[0082] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0083] The inorganic material may include, but is 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.

[0084] Organic and inorganic materials may exist mixed in a single coating layer, or may exist in a stacked form with a coating layer containing organic materials and a coating layer containing inorganic materials.

[0085] The separator (230) may be provided in pairs. The pair of separator (230) may be arranged to face each other on both sides of the first electrode plate (210) or the second electrode plate (220). The pair of separator (230) may be wound together with the first electrode plate (210) and the second electrode plate (220) around a winding axis.

[0086] A cap assembly (300) may be disposed at the upper portion of the side wall portion (110), that is, at the opening portion (130). The opening portion (130) of the can (100) is sealed by the cap assembly (300), and for this purpose, the cap assembly (300) may be combined with the can (100).

[0087] The cap assembly (300) can cover the opening (130) of the can (100). The cap assembly (300) may include a cap plate (310) and a terminal plate (320). That is, the cap plate (310) and the terminal plate (320) can cover the opening (130) of the can (100).

[0088] The cap plate (310) can be combined with the can (100), more specifically the side wall portion (120), to cover the outer area of ​​the opening (130). The cap plate (310) may include a through hole that exposes the central area of ​​the opening (130). The cap plate (310) can be directly combined with the side wall of the can (100) forming the opening (130) of the can (100) by a welding process or the like to cover the outer area of ​​the opening (130). The cap plate (310) attached to the can (100) may have the same polarity as the can (100), i.e., the second electrode plate (220).

[0089] The terminal plate (320) can cover the central area of ​​the opening (130), that is, the area corresponding to the through hole of the cap plate (310). The terminal plate (320) can be insulated and bonded to the cap plate (310). Thus, although not shown in the drawing, an insulating layer may be disposed between the cap plate (310) and the terminal plate (320). The insulating layer electrically insulates the cap plate (310) and the terminal plate (320) from each other. There are no special restrictions on the type of material forming the insulating layer, and it can be formed from insulating materials such as rubber, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), as well as insulating ceramics.

[0090] The lower surface of the terminal plate (320) covering the central area of ​​the opening (130) can be connected to the first electrode tab (240). Thus, the terminal plate (320) can have the same polarity as the first electrode (210).

[0091] FIG. 3 is a front view schematically showing the configuration of a conventional jelly roll type electrode assembly. Referring to FIG. 3, the jelly roll type electrode assembly (200A) includes an anode plate (210), a cathode plate (220), and a separator (230A). The jelly roll type electrode assembly (200A) may also further include a first electrode tab (240) with one end connected to the anode plate (210) and a second electrode tab (250) with one end connected to the cathode plate (220). Typically, in the jelly roll type electrode assembly (200A), the separator (230A) is positioned at the outermost edge of the electrode assembly (200), so in FIG. 3, the separator (230A) visible from the front, i.e., the outermost separator, is shown as a solid line. On the other hand, since the positive plate (210) and the negative plate (220) are covered by the separator (230A), the positive plate (210) and the negative plate (220) that are not visible from the front are shown as dotted lines.

[0092] Typically, in an electrode assembly, the sizes of the positive plate, the negative plate, and the separator differ. This is also the case for the jellyroll-type electrode assembly (200A) of FIG. 3. For example, in the jellyroll-type electrode assembly (200A), the size of the positive plate (210) may be the smallest and the size of the separator (230A) may be the largest, both in the width direction and in the length direction. And the size of the negative plate (220) may be of an intermediate size between that of the positive plate (210) and the separator (230A).

[0093] Accordingly, the separator (230A) may have a first overhang portion (OH1) in the width direction with respect to the negative plate (220), and may also have a second overhang portion (OH2) with respect to the negative plate (220) in the length direction. The first overhang portion (OH1) corresponds to the upper and lower portions in the width direction of the separator (230A), and the second overhang portion (OH2) corresponds to the end of the winding of the separator (230A) wound in a circular shape. The size of each of these first and second overhang portions (OH1, OH2) may vary depending on the type or size of the battery. For example, in the case of a coin-type battery, the first overhang portion (OH1) may have a length of about 0.6 mm, and the second overhang portion (OH2) may have a length of about 10 mm.

[0094] This jelly roll-type electrode assembly (200A) is inserted into the interior of the can (100) through the opening (130) at the top of the can (100). During the insertion process, the jelly roll-type electrode assembly (200A) may come into contact with the inner surface of the can (100), more specifically the side wall (120), and accordingly, the separator (230A) positioned at the outermost edge may be subjected to an upward force due to friction with the side wall (120).

[0095] As a result, the overhang portions (OH1, OH2) of the separator (230A), particularly the second overhang portion (OH2), may protrude upward. In particular, when the profile, i.e., the cutting shape at the end (E1) in the longitudinal direction of the separator (230A), has a straight shape parallel to the width direction, the second overhang portion (OH2) may protrude upward more. The second overhang portion (OH2) of the separator (230A) protruding upward may cause interference with the cap assembly (300) when the cap assembly (300) is placed at the top of the can (100), i.e., the opening (130) of the can (100), and the bonding surface is welded to join them. Due to this interference, not only may the separator (230) be damaged, but defects such as pinholes may also occur on the bonding surface between the can (100) and the cap assembly (300).

[0096] FIG. 4 is a front view schematically showing the configuration of a jelly roll type electrode assembly according to one embodiment. Compared to the conventional jelly roll type electrode assembly (200A) shown in FIG. 3, the components of the jelly roll type electrode assembly (200B) of FIG. 4 are the same, but the cutting shape (E2) of the separator (230B) differs from the cutting shape (E1) of the separator (230A) of FIG. 3. However, in FIG. 4, to make the technical concept of the present embodiment more clearly visible, only the negative plate (220), which is relatively larger in size among the positive plate (210) and the negative plate (220), is indicated by a dotted line, and the indication of the positive plate (210) is omitted.

[0097] Referring to FIG. 4, the cutting shape (E2) of the separator (230B) may have a curved shape in which the central portion is more convex than the lower portion with respect to the width direction. More specifically, the cutting shape (E2) of the separator (230B) may not be a straight line shape parallel to the width direction of the separator (230B), but may have a curved shape in which the central portion is convex. In this case, the upper portion and the lower portion of the cutting shape (E2) may be symmetrical with respect to the central portion, but is not limited thereto.

[0098] The cutting shape (E2) of this separator (230B) is an example of a shape in which at least the upper corner portion is removed from the second overhang portion (OH2), which is the winding end portion of the separator (230B). The second overhang portion (OH2) has a curved shape near the top. In FIG. 4, the lower corner of the second overhang portion (OH2) is also removed in the same shape as the upper corner. As a result, the cutting shape (E2) of the separator (230B) may have a shape in which the central portion is more convex than the upper or lower portions overall.

[0099] As illustrated in FIG. 4, when the upper corner portion of the second overhang portion (OH2) is removed, the overhang portion (OH2) may not protrude upward from the electrode assembly (200B) even if a force is applied upward to the separator (230B) positioned at the outermost edge in contact with the inner surface of the side wall portion (120) of the can (100) during the process of inserting the jelly roll type electrode assembly (200B) into the interior of the can (100) through the opening (130) of the upper portion of the can (100). As a result, even if the cap assembly (300) is placed in the opening (130) of the can (100) and the bonding surface is welded to join it, the separator (230B) may not interfere with the cap assembly (300).

[0100] FIG. 5 is a front view schematically showing the configuration of a jelly roll type electrode assembly according to another embodiment. Compared to the conventional jelly roll type electrode assembly (200A) shown in FIG. 3, the components of the jelly roll type electrode assembly (200C) of FIG. 5 are the same, but the cutting shape (E3) of the separator (230C) differs from the cutting shape (E1) of the separator (230A) of FIG. 3. However, in FIG. 5, to make the technical concept of the present embodiment more clearly visible, only the negative plate (220), which is relatively larger in size among the positive plate (210) and the negative plate (220), is indicated by a dotted line, and the indication of the positive plate (210) is omitted.

[0101] Referring to FIG. 5, the cutting shape (E3) of the separator (230C) may have a straight shape in which the central portion is more convex than the lower portion with respect to the width direction. More specifically, the cutting shape (E3) of the separator (230C) may not have a straight shape parallel to the width direction of the separator (230C), but rather a straight shape in which the central portion is convex. In this case, the upper portion and the lower portion of the cutting shape (E3) may be symmetrical with respect to the central portion, but is not limited thereto.

[0102] The cutting shape (E3) of this separator (230C) is another example of a shape in which at least the upper corner portion is removed from the second overhang portion (OH2), which is the winding end of the separator (230C). The second overhang portion (OH2) has a straight shape near the top. In FIG. 5, the lower corner of the second overhang portion (OH2) is also removed in the same shape as the upper corner. As a result, the cutting shape (E3) of the separator (230C) has a shape in which the central part is more convex than the upper or lower part.

[0103] FIG. 6 is a front view schematically showing the configuration of a jelly roll type electrode assembly according to another embodiment. Compared to the conventional jelly roll type electrode assembly (200A) shown in FIG. 3, the components of the jelly roll type electrode assembly (200D) of FIG. 6 are identical, but the cutting shape (E4) of the separator (230D) differs from the cutting shape (E1) of the separator (230A) of FIG. 3. However, in FIG. 6, to make the technical concept of the present embodiment more clearly visible, only the negative plate (220), which is relatively larger in size among the positive plate (210) and the negative plate (220), is indicated by a dotted line, and the indication of the positive plate (210) is omitted.

[0104] Referring to FIG. 6, the cutting shape (E4) of the separator (230D) may have a straight shape parallel to the width direction overall, but may have a shape (E41) in which the corner portion is removed only at the top. Accordingly, the separator (230D) may have a cutting shape in which only the top corner portion is removed, i.e., a chamfered shape (E41). The chamfered portion of the chamfered shape (E41) does not necessarily have to be a straight line; it may be a curve. Furthermore, there are no special restrictions on the size of the chamfered shape (E41), and it is sufficient to remove a portion of the second overhang portion (OH2) from the separator (230D).

[0105] The cutting shape (E41) of this separator (230D) is another example of a shape in which at least the upper corner is removed at the second overhang portion (OH2), which is the winding end of the separator (230D). In FIG. 6, the second overhang portion (OH2) is shown as being chamfered only at the top, but it is not limited to this. Unlike what is shown in FIG. 6, the second overhang portion (OH2) may also be chamfered at the bottom.

[0106] FIG. 7 is a front view schematically showing the configuration of a jelly roll type electrode assembly according to another embodiment. Compared to the conventional jelly roll type electrode assembly (200A) shown in FIG. 3, the components of the jelly roll type electrode assembly (200E) of FIG. 7 are identical, but the cutting shape (E5) of the separator (230E) differs from the cutting shape (E1) of the separator (230A) of FIG. 3. However, in FIG. 7, to make the technical concept of the present embodiment more clearly visible, only the negative plate (220), which is relatively larger in size among the positive plate (210) and the negative plate (220), is indicated by a dotted line, and the indication of the positive plate (210) is omitted.

[0107] Referring to FIG. 7, the cutting shape (E5) of the separator (230E) has a shape in which the width at the top is the smallest and the width at the bottom is the largest at the second overhang portion (OH2), which is the winding end of the separator (230C). This cutting shape (E5) of the separator (230E) may also be another example of a shape in which at least the top corner is removed. FIG. 7 is illustrated as having a width that continues to increase up to the bottom of the second overhang portion (OH2), but this is merely illustrative. Unlike what is shown in FIG. 7, the width of the second overhang portion (OH2) may gradually increase from the top to the center, and then remain constant from the center to the bottom.

[0108] Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom.

[0109] Therefore, the technical scope of protection of the present invention should be determined by the following patent claims.

Claims

Claim 1 An electrode assembly formed by winding a laminate having a separator interposed between a positive plate and a negative plate multiple times to have a winding center, wherein the cutting shape at the winding end of the separator has a shape in which the upper end is removed. Claim 2 An electrode assembly according to claim 1, characterized in that the cutting shape has a shape in which the upper portion of the separator is removed in a curve. Claim 3 An electrode assembly according to claim 1, characterized in that the cutting shape has a shape in which the upper portion of the separator is removed in a straight line. Claim 4 An electrode assembly according to paragraph 3, characterized in that the cutting shape has a shape in which the corner portion is removed only at the top. Claim 5 An electrode assembly according to claim 1, characterized in that the cutting shape has a shape in which the lower end of the winding end of the separator is also removed. Claim 6 An electrode assembly according to claim 5, characterized in that the cutting shape has an upper and lower symmetrical shape with respect to the width direction of the separator. Claim 7 An electrode assembly according to claim 6, characterized in that the cutting shape has a shape in which the central part is more convex than the top and bottom with respect to the width direction of the separator. Claim 8 An electrode assembly according to claim 7, characterized in that the cutting shape has a shape in which the upper and lower portions of the separator are each removed in a curved manner. Claim 9 In claim 7, the electrode assembly is characterized in that the cutting shape has a shape in which the upper portion and the lower portion of the separator are each removed in a straight line. Claim 10 An electrode assembly according to claim 9, characterized in that the cutting shape has a shape in which corner portions are removed at the top and bottom, respectively. Claim 11 An electrode assembly formed by winding a laminate having a separator interposed between an anode plate and a cathode plate multiple times to have a winding center, wherein the separator has an overhang portion in the longitudinal direction with respect to the anode plate and the cathode plate, and the overhang portion is characterized in that the width of the upper portion is smaller than the width of the central portion. Claim 12 An electrode assembly according to claim 11, characterized in that the widthwise boundary of the overhang portion has a curved cutting shape near the top. Claim 13 An electrode assembly according to claim 11, characterized in that the widthwise boundary of the overhang portion has a straight cutting shape near the top. Claim 14 An electrode assembly according to claim 13, characterized in that the overhang portion has a cutting shape in which the corner portion is removed only at the top of the central portion. Claim 15 An electrode assembly according to claim 11, characterized in that the width of the lower part of the overhang portion is also smaller than the central portion. Claim 16 An electrode assembly according to claim 15, characterized in that the width-direction boundary of the overhang portion has a vertically symmetric cutting shape with respect to the width direction of the separator. Claim 17 An electrode assembly according to claim 16, characterized in that the widthwise boundary of the overhang portion has a curved cutting shape in which the central portion is more convex than the upper and lower portions based on the widthwise direction of the separator. Claim 18 An electrode assembly according to claim 16, characterized in that the width-direction boundary of the overhang portion has a straight cutting shape in which the central portion is more convex than the upper and lower portions with respect to the width direction of the separator. Claim 19 An electrode assembly according to claim 18, characterized in that the overhang portion has a shape in which corner portions are removed at the top and bottom, respectively. Claim 20 A battery comprising: a can having a cylindrical shape and an opening having an open top; an electrode assembly formed by winding a laminate, in which a separator is interposed between a positive plate and a negative plate, multiple times to have a winding center; and a cap assembly joined to the top of the can to cover the opening, wherein the cutting shape at the winding end of the separator has a shape in which the top is removed.

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