Secondary battery, secondary battery manufacturing method and battery module

Abstract

The present disclosure relates to a secondary battery and a battery module including the same. The technical problem to be solved is to provide a secondary battery, a method for manufacturing a secondary battery, and a battery module capable of preventing thermal damage to a gasket caused by welding heat during welding between a case and a cap plate. To this end, the present disclosure provides a secondary battery comprising a case, an electrode assembly accommodated in the case, a cap plate having a pair of terminals having different polarities and a welded portion formed by welding to the case, and a gasket disposed between the cap plate and the terminals, wherein the terminals include a first terminal portion connected to the electrode assembly and a second terminal portion extending from the first terminal portion and disposed between the welded portion and the first terminal portion.

Description

Technology Field

[0001] The present disclosure relates to a secondary battery, a method for manufacturing a secondary battery, and a battery module. Background Technology

[0002] In general, accompanied by the recent rapid proliferation of electronic devices using batteries, such as mobile phones, laptop computers, and electric vehicles, the demand for high-energy-density, high-capacity rechargeable batteries is rapidly increasing. Accordingly, research and development to improve the performance of lithium-ion batteries is actively underway.

[0003] A lithium secondary battery is a battery comprising a positive electrode and a negative electrode containing an active material capable of lithium ion intercalation and deintercalation, and an electrolyte, which produces electrical energy through oxidation and reduction reactions when lithium ions are intercalated or deintercalated from the positive and negative electrodes.

[0004] 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

[0005] The purpose of the present invention is to provide a secondary battery, a method for manufacturing a secondary battery, and a battery module capable of preventing thermal damage to a gasket caused by welding heat during welding between a case and a cap plate.

[0006] The purpose of the present invention is to provide a secondary battery capable of maximizing the contact area between a terminal and a gasket, a method for manufacturing a secondary battery, and a battery module.

[0007] However, the technical problems that the present invention 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

[0008] A secondary battery according to the present invention for solving the above technical problem comprises: a case, an electrode assembly accommodated in the case, a cap plate welded to the case to form a welded portion and having a pair of terminals having different polarities, and a gasket disposed between the cap plate and the terminals, wherein the terminals include a first terminal portion connected to the electrode assembly and a second terminal portion extending from the first terminal portion and disposed between the welded portion and the first terminal portion.

[0009] The second terminal portion may include a first terminal surface facing the cap plate, a second terminal surface arranged to face in a direction opposite to the first terminal surface, and a third terminal surface that connects the first terminal surface and the second terminal surface and is arranged to intersect the first terminal surface and the second terminal surface.

[0010] The first terminal surface may be provided with a terminal groove portion that is formed by being recessed toward the second terminal surface and surrounds the gasket.

[0011] The width of the first terminal surface, excluding the width of the terminal groove portion, may be 0.7 mm or more and 0.9 mm or less.

[0012] The depth of the above terminal groove may be 0.7 mm or more and 0.9 mm or less.

[0013] The first terminal surface and the third terminal surface are in contact with the gasket, and the second terminal surface may not be in contact with the gasket.

[0014] The above terminal may further include a connecting portion connecting the first terminal portion and the second terminal portion.

[0015] The above connection part may be provided with an inclined surface that contacts the gasket and is positioned at a set angle.

[0016] The above connection part may be provided with a stepped surface that contacts the gasket.

[0017] The above stepped surface may include a first stepped surface connected to the first terminal portion and a second stepped surface connected to the second terminal portion and arranged to intersect with the first stepped surface.

[0018] The above cap plate may include a first plate surface facing the electrode assembly, a second plate surface positioned to face in a direction opposite to the first plate surface, and a plate groove portion formed by being recessed into the first plate surface to surround the gasket.

[0019] The above cap plate may further include a plate protrusion that protrudes from the second plate surface and at least a portion of which contacts the gasket.

[0020] The above gasket may include a gasket body portion penetrating the cap plate, a first gasket extension portion extending from the gasket body portion and positioned facing the first plate surface, a second gasket extension portion extending from the gasket body portion and positioned facing the plate protrusion, and a third gasket extension portion extending from the second gasket extension portion and positioned facing the second terminal portion.

[0021] The third gasket extension can be non-contacting with the plate protrusion.

[0022] The distance between the above welded portion and the above third gasket extension portion may be greater than the thickness of the above terminal.

[0023] The distance between the above welded part and the above third gasket extension part may be 2.5 mm or more and 4 mm or less.

[0024] The ratio of the distance between the welded portion and the third gasket extension portion to the width of the cap plate may be 8.9 or more and 16.1 or less.

[0025] The width of the third gasket extension part above may be 0.7 mm or more and 0.9 mm or less.

[0026] A method for manufacturing a secondary battery according to the present invention comprises: a step of placing a cap plate and a terminal between a first mold and a second mold; a step of moving the first mold toward the second mold to form a cavity; and a step of injecting resin into the cavity to form a gasket.

[0027] A battery module according to the present invention comprises: a housing and a plurality of secondary batteries disposed inside the housing, wherein the secondary batteries comprise a case, an electrode assembly accommodated in the case, a cap plate welded to the case to form a welded portion and having a pair of terminals having different polarities, and a gasket disposed between the cap plate and the terminals, wherein the terminals comprise a first terminal portion connected to the electrode assembly and a second terminal portion extending from the first terminal portion and disposed between the welded portion and the first terminal portion. Effects of the invention

[0028] According to the present invention, by increasing the distance between the gasket and the weld, thermal damage to the gasket caused by welding heat during welding between the case and the cap plate can be prevented.

[0029] According to the present invention, the contact area between the terminal and the gasket can be maximized to increase the bonding strength of the gasket during injection molding of the gasket.

[0030] 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

[0031] 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 battery module according to one embodiment of the present invention. FIG. 2 is a perspective view schematically showing the configuration of a secondary battery according to one embodiment of the present invention. FIG. 3 is an exploded perspective view schematically showing the configuration of a secondary battery according to one embodiment of the present invention. FIG. 4 is a schematic diagram showing the configuration of an electrode assembly according to one embodiment of the present invention. FIG. 5 is a partial cross-sectional view schematically showing the configuration of a secondary battery according to one embodiment of the present invention. Figure 6 is an enlarged view of Figure 5. FIG. 7 is a partial cross-sectional view schematically showing the configuration of a secondary battery according to another embodiment of the present invention. Figure 8 is an enlarged view of Figure 7. FIG. 9 is a flowchart schematically illustrating a method for manufacturing a secondary battery according to one embodiment of the present invention. FIGS. 10 to 13 are schematic diagrams illustrating a secondary battery manufacturing process according to one embodiment of the present invention. Specific details for implementing the invention

[0032] Hereinafter, preferred embodiments of the present invention will be described in detail 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, but should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. Accordingly, 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; therefore, it should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application.

[0033] Additionally, as used herein, “comprise, include” and / or “comprising, 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] Throughout the specification, unless specifically stated otherwise, each component may be singular or plural.

[0038] 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.

[0039] Furthermore, where one component is described as being "on," "connected to," or "coupled to" another component, it should be understood that while the components may be directly connected or coupled to each other, another component may be "interposed" between each component, or that each component may be "connected," "coupled," or "coupled" through another component.

[0040] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Additionally, the use of “may” when describing embodiments of the present disclosure relates to “one or more embodiments of the present disclosure.” Expressions such as “one or more” and “one or more” preceding a list of elements modify the entire list of elements and do not modify individual elements of the list.

[0041] Throughout the specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise, and "C to D" means C or more and D or less, unless specifically stated otherwise.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] The terms used in this specification are intended to describe embodiments of the present disclosure and are not intended to limit the present disclosure.

[0047] FIG. 1 is a perspective view schematically showing the configuration of a battery module according to one embodiment of the present invention.

[0048] Referring to FIG. 1, the battery module according to the present embodiment may include a housing (10), a secondary battery (20), and a bus bar (30).

[0049] The housing (10) forms the general outline of the battery module and can provide a space in which a secondary battery (20) can be accommodated. The housing (10) may include a housing body (11) and a housing cover (12).

[0050] The housing body (11) can be formed to have a box shape with an empty interior and one side open. The cross-sectional shape of the housing body (11) is not limited to the square shape shown in FIG. 1, but can be designed to have various shapes such as polygons, circles, and ellipses.

[0051] The housing cover (12) is coupled to the housing body (11) and can close the internal space of the housing body (11). For example, the housing cover (12) may be formed to have a shape of approximately a plate and may be positioned to face the open side of the housing body (11).

[0052] The housing cover (12) can be fixed to the housing body (11) by various types of joining methods such as bolting, welding, and snap-fitting.

[0053] The secondary battery (20) can function as a unit structure that stores and supplies power in the battery module. The secondary battery (20) can be placed inside the housing (10).

[0054] The secondary batteries (20) may be provided in multiple numbers. The multiple secondary batteries (20) may be arranged in at least two rows along at least one of the length direction (X-axis direction in FIG. 1) or width direction (Y-axis direction in FIG. 1) of the housing (10).

[0055] In FIG. 1, a plurality of secondary batteries (20) are shown arranged in six rows along the length direction of the housing (10) as an example, but the arrangement of the plurality of secondary batteries (20) is not limited to this and can be designed in various forms.

[0056] Multiple secondary batteries (20) can be arranged side by side. The number of secondary batteries (20) can be varied depending on the size, shape, etc. of the housing (10).

[0057] Multiple secondary batteries (20) can be electrically connected by a bus bar (30).

[0058] The bus bar (30) according to the present embodiment can be placed between the housing cover (12) and the secondary battery (20).

[0059] The bus bar (30) may be provided in multiple numbers. Each bus bar (30) can connect an adjacent pair of secondary batteries (20) in series or in parallel.

[0060] The bus bar (30) can be formed from an electrically conductive material such as copper, aluminum, or nickel. The specific shape of the bus bar (30) is not limited to the shape shown in FIG. 1, and can be designed to various shapes that can electrically connect adjacent secondary batteries (20).

[0061] Multiple bus bars (30) can be supported inside the housing (10) by a bus bar holder (40).

[0062] The bus bar holder (40) according to the present embodiment may be formed to have a flat plate shape. The bus bar holder (40) may be placed between the housing cover (12) and the secondary battery (20).

[0063] The bus bar (30) can be fixed to the bus bar holder (40) by various types of joining methods, such as snap joining, bolting, and injection joining. The bus bar holder (40) can be configured to include an electrically insulating polymer compound material.

[0064] Below, a secondary battery (20) according to various embodiments of the present invention will be described.

[0065] FIG. 2 is a schematic perspective view showing the configuration of a secondary battery according to one embodiment of the present invention, and FIG. 3 is an exploded perspective view showing the configuration of a secondary battery according to one embodiment of the present invention.

[0066] In the following description, the secondary battery (20) is described as a prismatic battery as a lithium-ion secondary battery (20). However, the present invention is not limited thereto, and the secondary battery (20) may be a lithium polymer battery or a cylindrical battery.

[0067] Referring to FIGS. 1 to 3, the secondary battery (20) according to the present embodiment may include a case (100), an electrode assembly (200), a cap plate (300), a terminal (400), and a gasket (500).

[0068] The case (100) forms the general appearance of the secondary battery (20) and can accommodate an electrode assembly (200). The case (100) may include a bottom portion (110), a front portion (120), a rear portion (130), a first side portion (140), and a second side portion (150).

[0069] The bottom portion (110) can form the lower (based on FIG. 3) exterior of the case (100). The bottom portion (110) according to the present embodiment may have the shape of a rectangular plate. The bottom portion (110) may be seated on the bottom surface of the housing body (11).

[0070] The front portion (120), rear portion (130), first side portion (140) and second side portion (150) can form the periphery surface of the case (100).

[0071] The front portion (120), rear portion (130), first side portion (140), and second side portion (150) may have the shape of a plate extending upward from the edge of the bottom portion (110) (based on FIG. 3).

[0072] The front portion (120), rear portion (130), first side portion (140), and second side portion (150) may be arranged to surround the upper space of the bottom portion (110). The front portion (120), rear portion (130), first side portion (140), and second side portion (150) may be arranged to form a rectangular cross-sectional shape.

[0073] The front portion (120) and the rear portion (130) may be positioned facing each other along the longitudinal direction of the housing (10) (X-axis direction based on FIG. 1). The front portion (120) and the rear portion (130) may be positioned parallel to each other. The areas of the front portion (120) and the rear portion (130) may be equal to each other.

[0074] The first side portion (140) and the second side portion (150) may be arranged facing each other along the width direction (Y-axis direction based on FIG. 1) of the housing (10). The first side portion (140) and the second side portion (150) may be arranged parallel to each other.

[0075] The areas of the first side section (140) and the second side section (150) may be equal to each other. The areas of the first side section (140) and the second side section (150) may be smaller than the areas of the front section (120) and the rear section (130).

[0076] The case (100) may further include an opening (160). The opening (160) may refer to a space enclosed by the upper portions of the front portion (120), the rear portion (130), the first side portion (140), and the second side portion (150). The opening (160) may interconnect the internal space and the external space of the case (100).

[0077] Accordingly, the case (100) according to the present embodiment may have the shape of a rectangular prism with the upper side (based on FIG. 3) open.

[0078] The first direction described below may mean a direction parallel to the Z-axis with respect to FIGS. 2 and FIGS. 3, extending from the bottom portion (110) toward the opening portion (160). The second direction may mean a direction parallel to the Y-axis with respect to FIGS. 2 and FIGS. 3, extending from the second side portion (150) toward the first side portion (140). The third direction may mean a direction parallel to the X-axis with respect to FIGS. 2 and FIGS. 3, extending from the rear portion (130) toward the front portion (120).

[0079] The electrode assembly (200) can function as a unit structure that performs charging and discharging operations of power in a secondary battery (20). The electrode assembly (200) can be accommodated inside a case (100).

[0080] FIG. 4 is a schematic diagram showing the configuration of an electrode assembly according to one embodiment of the present invention.

[0081] Referring to FIGS. 1 to 4, the electrode assembly (200) according to the present embodiment may include a first electrode (210), a second electrode (220), and a separator (230) disposed between the first electrode (210) and the second electrode (220). The first electrode (210), the separator (230), and the second electrode (220) may be provided in multiple numbers.

[0082] Hereinafter, the electrode assembly (200) will be described as having a stacked form in which a plurality of first electrodes (210), separators (230), and second electrodes (220) are sequentially stacked along a third direction. However, the electrode assembly (200) is not limited to such a form, and it is also possible to form a shape in which the first electrodes (210), separators (230), and second electrodes (220) are stacked and wound along a clockwise or counterclockwise direction around a winding axis.

[0083] The first electrode (210) can function as either the positive or negative electrode of the electrode assembly (200). Hereinafter, the first electrode (210) will be described as an example of being the positive electrode of the electrode assembly (200). However, the first electrode (210) is not limited thereto, and it is also possible for it to function as the negative electrode of the electrode assembly (200).

[0084] The first electrode (210) according to the present embodiment may be formed to have the shape of a foil including a metal material such as aluminum or an aluminum alloy.

[0085] The first electrode (210) is not particularly limited in type, size, shape, etc., as long as it is conductive without causing chemical changes in the secondary battery (20).

[0086] The cross-sectional shape of the first electrode (210) can be designed to have various shapes in addition to the rectangle shown in FIG. 4.

[0087] The first electrode (210) may be provided in multiple numbers. The multiple first electrodes (210) may be arranged along a third direction between the front portion (120) and the rear portion (130) of the case (100). The number of first electrodes (210) can be varied in design depending on the charging capacity of the secondary battery (20), etc.

[0088] A first active material layer (211) may be applied to at least a portion of the first electrode (210). The first active material layer (211) may be applied to both sides of the first electrode (210), or alternatively, it may be applied to only one side of the first electrode (210).

[0089] In this embodiment, as the first electrode (210) functions as a positive electrode, the first active material layer (211) may include a positive electrode active material.

[0090] 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.

[0091] 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.

[0092] The positive electrode active material may include only one of lithium-iron-phosphorus oxide (LiFePO4, LFP), lithium-manganese-iron-phosphorus oxide (LiMnFePO4, LMFP), and lithium-nickel-cobalt-manganese oxide (LiNixCoyMnzO2, NCM), and it is also possible to include any two of lithium-iron-phosphorus oxide (LiFePO4, LFP), lithium-manganese-iron-phosphorus oxide (LiMnFePO4, LMFP), and lithium-nickel-cobalt-manganese oxide (LiNixCoyMnzO2, NCM), or all of these.

[0093] The first active material layer (211) may further include an anode conductive material.

[0094] The positive electrode conductive material is used to impart conductivity to the first active material layer (211), and any electronically conductive material that does not cause chemical changes can be used.

[0095] Examples of positive electrode 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.

[0096] The first active material layer (211) may further include an anode binder.

[0097] The positive binder serves to adhere the particles constituting the positive active material well to each other and also to adhere the positive active material well to the first electrode (210).

[0098] Examples of positive binders may include non-aqueous binders, aqueous binders, dry binders, or combinations thereof.

[0099] 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.

[0100] 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.

[0101] When using a water-based binder as the anode binder, a cellulose-based compound capable of imparting viscosity may be further included. As cellulose-based compounds, one or more types such as carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or alkali metal salts thereof may be mixed and used. Na, K, or Li may be used as the alkali metal.

[0102] 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.

[0103] The first electrode (210) may include a first uncoated portion (212) on which the first active material layer (211) is not coated.

[0104] The first non-removable portion (212) according to the present embodiment may be disposed in the upper portion of the first electrode (210) positioned to face the opening (160) inside the case (100). However, the first non-removable portion (212) is not limited to this shape and may also be formed over the entire edge portion of the first electrode (210).

[0105] The second electrode (220) can function as either the positive or negative electrode of the electrode assembly (200). Hereinafter, the second electrode (220) will be described as an example of being the negative electrode of the electrode assembly (200). However, the second electrode (220) is not limited to this, and it is also possible for it to function as the positive electrode of the electrode assembly (200).

[0106] The second electrode (220) may be provided in multiple numbers. The multiple second electrodes (220) may be arranged along a third direction between the front portion (120) and the rear portion (130) of the case (100).

[0107] The first electrode (210) and the second electrode (220) may be alternately arranged along the third direction. The second electrode (220) may be spaced apart from the first electrode (210) at a set interval along the third direction.

[0108] The second electrode (220) according to the present embodiment may be formed to have the shape of a foil including a metal material such as copper, copper alloy, nickel, or nickel alloy.

[0109] The second electrode (220) is not particularly limited in type, size, shape, etc., as long as it is conductive and does not cause chemical changes in the secondary battery (20).

[0110] The cross-sectional shape of the second electrode (220) can be designed to have various shapes in addition to the rectangular shape shown in FIG. 4.

[0111] A second active material layer (221) may be applied to at least a portion of the second electrode (220). The second active material layer (221) may be applied to both sides of the second electrode (220), or alternatively, it may be applied to only one side of the second electrode (220).

[0112] As the second electrode (220) functions as a negative electrode, the second active material layer (221) may include a negative active material.

[0113] 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.

[0114] Materials capable of reversibly intercalating / deintercalating lithium ions may include carbon-based negative electrode active materials, for example, crystalline carbon, amorphous carbon, or a combination thereof.

[0115] Examples of crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, and examples of amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0116] 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.

[0117] As materials capable of doping and undoping lithium, Si-based negative electrode active materials or Sn-based negative electrode active materials may be used. Si-based negative electrode active materials may be silicon, silicon-carbon composites, SiOx (0 < x < 2), Si-Q alloys (wherein 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.

[0118] A silicon-carbon composite may be a composite of silicon and amorphous carbon. 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.

[0119] Amorphous carbon can be located between silicon primary particles, for example, silicon primary particles can be coated with amorphous carbon. Secondary particles can be dispersed in the amorphous carbon matrix.

[0120] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core comprising crystalline carbon and silicon particles, and an amorphous carbon coating layer located on the surface of the core.

[0121] Si-based or Sn-based cathode active materials can be used in combination with carbon-based cathode active materials.

[0122] The second active material layer (221) may further include a negative electrode conductive material and a negative electrode binder.

[0123] The cathode conductive material is used to impart conductivity to the second active material layer (221), and any electronically conductive material that does not cause chemical changes can be used.

[0124] Examples of cathode conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metal-based materials in the form of metal powders or metal fibers containing copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0125] The negative electrode binder serves to adhere the particles constituting the negative electrode active material well to each other and also to adhere the negative electrode active material well to the second electrode (220).

[0126] Examples of cathode binders may include non-aqueous binders, aqueous binders, dry binders, or combinations thereof.

[0127] 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.

[0128] 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.

[0129] When using a water-based binder as the cathode binder, a cellulose-based compound capable of imparting viscosity may be further included. As cellulose-based compounds, 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.

[0130] 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.

[0131] The second electrode (220) may include a second uncoated portion (222) where the second active material layer (221) is not coated.

[0132] The second non-removable portion (222) according to the present embodiment may be disposed in the upper portion of the second electrode (220) positioned to face the opening (160) inside the case (100). However, the second non-removable portion (222) is not limited to this shape and may also be formed over the entire edge portion of the second electrode (220).

[0133] A separator (230) may be placed between the first electrode (210) and the second electrode (220). The separator (230) may perform the function of preventing a short circuit between the first electrode (210) and the second electrode (220) while allowing the movement of lithium ions between the first electrode (210) and the second electrode (220).

[0134] The separator (230) can be positioned to completely cover the surface area of ​​the electrode assembly (200). Accordingly, the separator (230) can prevent the first electrode (210) and the second electrode (220) from being directly exposed to the outside of the electrode assembly (200).

[0135] 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.

[0136] 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.

[0137] The porous substrate may be a polymer membrane formed from any one polymer selected from 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.

[0138] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0139] 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.

[0140] 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.

[0141] The electrode assembly (200) according to the present embodiment may further include a first electrode tab (240) and a second electrode tab (250).

[0142] The first electrode tab (240) is connected to the first electrode (210) and may protrude outward from the electrode assembly (200). As the first electrode (210) is exemplified as a positive electrode, the first electrode tab (240) may function as a positive electrode tab of the secondary battery (20). However, the first electrode tab (240) is not limited thereto, and if the first electrode (210) is a negative electrode, it may function as a negative electrode tab of the secondary battery (20).

[0143] The first electrode tab (240) according to the present embodiment may extend along a first direction from the electrode assembly (200). For example, the first electrode tab (240) may extend toward an opening (160) inside the case (100).

[0144] According to the present embodiment, the first electrode tab (240) may be provided in multiple numbers. The multiple first electrode tabs (240) may be spaced apart along the second direction. Although FIG. 3 illustrates an example where the first electrode tab (240) is formed in two numbers, the number of first electrode tabs (240) is not limited to this and can be designed to have various numbers, such as three or four.

[0145] The first electrode tab (240) may include a first tab member (241).

[0146] The first tab member (241) according to the present embodiment may have the shape of a foil extending along a first direction from the first unworn portion (212) of the first electrode (210).

[0147] The first tab member (241) may have a roughly rectangular shape. However, the shape of the first tab member (241) is not limited to this, and the design can be changed to various shapes.

[0148] The first tap member (241) may be formed integrally with the first electrode (210). For example, the first tap member (241) may be the remaining area of ​​the first unused portion (212) after a portion of the first unused portion (212) has been cut or removed by notching or the like. Alternatively, the first tap member (241) may be manufactured separately from the first electrode (210) and then connected to the first unused portion (212) by welding or the like. The material of the first tap member (241) may be the same as the material of the first electrode (210).

[0149] The first tap member (241) may be provided in multiple numbers. The number of the first tap member (241) may be equal to the number of the first electrode (210). Each first tap member (241) may extend individually from the first non-tap portion (212) of the different first electrode (210).

[0150] Adjacent first tab members (241) may be arranged facing each other along a third direction. Adjacent first tab members (241) may be arranged parallel to each other.

[0151] Accordingly, the first electrode tab (240) according to the present embodiment may be an assembly of a plurality of first tab members (241) stacked along a third direction. Adjacent first tab members (241) may come into contact with each other, and may also be spaced apart by the thickness of the separator (230).

[0152] The second electrode tab (250) is connected to the second electrode (220) and may protrude outward from the electrode assembly (200). As the second electrode (220) is exemplified as a negative electrode, the second electrode tab (250) may function as a negative electrode tab of the secondary battery (20). However, the second electrode tab (250) is not limited thereto, and if the second electrode (220) is a positive electrode, it may function as a positive electrode tab of the secondary battery (20).

[0153] The second electrode tab (250) according to the present embodiment may extend along a first direction from the electrode assembly (200). That is, the second electrode tab (250) may extend toward the opening (160) inside the case (100).

[0154] The first electrode tab (240) and the second electrode tab (250) may be spaced apart along the second direction. For example, the second electrode tab (250) may be positioned at a set distance from the first electrode tab (240) along the second direction.

[0155] The second electrode tabs (250) according to the present embodiment may be provided in a plurality. The plurality of second electrode tabs (250) may be spaced apart along the second direction.

[0156] In FIG. 3, the second electrode tab (250) is shown as being formed in two numbers, but the number of second electrode tabs (250) is not limited to this and can be designed to have various numbers such as three or four.

[0157] The second electrode tab (250) may include a second tab member (251).

[0158] The second tab member (251) according to the present embodiment may have the shape of a foil extending along the first direction from the second unlit portion (222) of the second electrode (220).

[0159] The second tab member (251) may have a roughly rectangular shape. However, the shape of the second tab member (251) is not limited to this, and the design can be changed to various shapes.

[0160] The second tap member (251) may be formed integrally with the second electrode (220). For example, the second tap member (251) may be the remaining area of ​​the second unused portion (222) after a portion of the second unused portion (222) has been cut or removed by notching or the like. Alternatively, the second tap member (251) may be manufactured separately from the second electrode (220) and then connected to the second unused portion (222) by welding or the like. The material of the second tap member (251) may be the same as the material of the second electrode (220).

[0161] The second tap member (251) may be provided in multiple numbers. The number of the second tap member (251) may be equal to the number of the second electrode (220). Each second tap member (251) may extend individually from the second non-tap portion (222) of the different second electrode (220).

[0162] Adjacent second tab members (251) may be arranged facing each other along a third direction. Adjacent second tab members (251) may be arranged parallel to each other.

[0163] Accordingly, the second electrode tab (250) according to the present embodiment may be an assembly of a plurality of second tab members (251) stacked along a third direction. Adjacent second tab members (251) may come into contact with each other, and may also be spaced apart by the thickness of the separator (230).

[0164] The cap plate (300) can be attached to the case (100) to seal the case (100).

[0165] The cap plate (300) according to the present embodiment may be formed to have a flat plate shape. The cap plate (300) may be placed in the opening (160) of the case (100).

[0166] The cap plate (300) may be positioned facing the electrode assembly (200) along a first direction. That is, the cap plate (300) may be positioned at a set distance from the electrode assembly (200) in a first direction. The cap plate (300) may be positioned parallel to the bottom portion (110) of the case (100).

[0167] The cap plate (300) can be seated on the upper part of the case (100), more specifically, on the upper part of the front part (120), rear part (130), first side part (140), and second side part (150). The cap plate (300) can be joined to the case (100) by welding.

[0168] The edge of the cap plate (300) and the top of the case (100) can be joined together by laser welding. Thus, a weld (300a) can be formed on the cap plate (300). The weld (300a) can be formed along the edge of the cap plate (300).

[0169] FIG. 5 is a partial cross-sectional view schematically showing the configuration of a secondary battery according to one embodiment of the present invention, and FIG. 6 is an enlarged view of FIG. 5.

[0170] Referring to FIGS. 1 to 6, the cap plate (300) according to the present embodiment may include a first plate surface (310), a second plate surface (320), a plate groove (330), and a plate protrusion (340).

[0171] The first plate surface (310) and the second plate surface (320) may be spaced apart along the first direction. The first plate surface (310) may be positioned to face the electrode assembly (200).

[0172] The first plate surface (310) can be exemplified as the lower surface of a cap plate (300) positioned to face the upper surface of an electrode assembly (200) in which the first electrode tab (240) and the second electrode tab (250) protrude.

[0173] The second plate surface (320) may be positioned to face the external space of the case (100). The second plate surface (320) may be exemplified as the upper surface of a cap plate (300) positioned to face in a direction opposite to that of the first plate surface (310).

[0174] The plate groove portion (330) may have the shape of a groove formed by being recessed from the first plate surface (310) of the cap plate (300) toward the second plate surface (320). The plate groove portion (330) may be positioned to surround the first gasket extension portion (520) of the gasket (500).

[0175] The plate protrusion (340) may have the shape of a projection protruding along a first direction from the second plate surface (320) of the cap plate (300). At least a portion of the plate protrusion (340) may come into contact with the gasket (500). The plate protrusion (340) may come into contact with the second gasket extension (530) of the gasket (500).

[0176] The cap plate (300) according to the present embodiment may be provided with a vent hole (301) and a vent (302).

[0177] The vent hole (301) can be formed to have the shape of a hole that penetrates the cap plate (300) vertically along the first direction. The vent hole (301) can provide a path for flames, gas, smoke, etc. formed inside the case (100) to be discharged to the outside of the case (100) when the secondary battery (20) undergoes thermal runaway due to overcurrent, etc. The cross-sectional shape of the vent hole (301) can be designed to have various shapes, such as elliptical, circular, or polygonal.

[0178] The vent (302) is installed in the vent hole (301) and can be opened and closed in conjunction with changes in the internal pressure of the case (100). That is, the vent (302) can close the vent hole (301) during normal operation of the secondary battery (20) to prevent the electrolyte inside the case (100) from leaking out of the case (100) or moisture, foreign substances, etc. from entering the case (100).

[0179] The vent (302) can open the vent hole (301) during thermal runaway of the secondary battery (20) to induce flames, gas, smoke, etc. formed inside the case (100) to be discharged to the outside of the case (100).

[0180] The vent (302) can be formed to have a shape roughly like a plate. The vent (302) can be fixed to the cap plate (300) by various types of joining methods such as welding, bolting, and snap joining.

[0181] The vent (302) may be positioned inside the vent hole (301), or positioned above or below the cap plate (300) so as to face the vent hole (301) along the first direction.

[0182] The thickness of the vent (302) parallel to the first direction may be smaller than the thickness of the cap plate (300). Accordingly, the vent (302) can be easily ruptured or broken when the internal pressure of the case (100) increases.

[0183] The vent (302) may include a notch formed concavely on the inner side of the vent (302) so as to be preferentially broken when the internal pressure of the case (100) increases.

[0184] In the cap plate (300) according to the present embodiment, an electrolyte injection port (303) may be formed that penetrates the cap plate (300) and can be fitted with a sealing plug.

[0185] The electrolyte injection port (303) may be positioned at a set interval from the vent hole (301) in the second direction or in the opposite direction of the second direction.

[0186] A plate hole (304) may be formed in the cap plate (300) according to the present embodiment. The plate hole (304) may have the shape of a hole penetrating the cap plate (300) along a first direction.

[0187] The plate holes (304) may be provided in pairs. The pair of plate holes (304) may be spaced apart at a set interval along the second direction. The vent hole (301) and the electrolyte injection port (303) may be placed between the pair of plate holes (304).

[0188] An insulating plate (305) may be disposed between the cap plate (300) and the electrode assembly (200) according to the present embodiment. The insulating plate (305) can insulate the cap plate (300) and the electrode assembly (200) by preventing direct contact between the cap plate (300) and the electrode assembly (200).

[0189] The insulating plate (305) can fix the position of the electrode assembly (200) inside the case (100). The insulating plate (305) can prevent the electrode assembly (200) from being damaged if the cap plate (300) is deformed inwardly into the case (100) due to external impact or the like.

[0190] The insulating plate (305) according to the present embodiment may be arranged to face the electrode assembly (200) along a first direction inside the case (100). That is, the electrode assembly (200), the insulating plate (305), and the cap plate (300) may be arranged sequentially along the first direction.

[0191] The insulating plate (305) can be fixed to the inner surface of the case (100) by various types of joining methods such as snap joining, welding, bolting, and bonding.

[0192] The insulating plate (305) can be in contact with one side of the electrode assembly (200) to which the first electrode tab (240) and the second electrode tab (250) are extended.

[0193] The insulating plate (600) can be formed from an insulating material such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET) rubber, etc.

[0194] A terminal (400) may be provided in the cap plate (300) according to the present embodiment.

[0195] The terminal (400) can function as a configuration that provides an electrical connection of the secondary battery (20) to the bus bar (30) or an external power device.

[0196] The terminal (400) according to the present embodiment may be formed of an electrically conductive material such as aluminum, nickel, copper, etc. The terminal (400) may protrude outward from the cap plate (300). For example, the terminal (400) may be positioned at a set distance along a first direction from the second plate surface (320) of the cap plate (300).

[0197] In the drawing, the terminal (400) is illustrated as having a rectangular cross-sectional shape, but the cross-sectional shape of the terminal (400) is not limited to this and can be designed to have various shapes such as a circle, ellipse, or polygon.

[0198] The terminal (400) according to the present embodiment may include a first terminal portion (410), a second terminal portion (420), and a connection portion (430).

[0199] The first terminal portion (410) can be connected to the electrode assembly (200). The lower surface of the first terminal portion (410) can be positioned to face the plate hole (304) formed by penetrating the cap plate (300). The cross-sectional area of ​​the first terminal portion (410) may be smaller than the cross-sectional area of ​​the plate hole (304).

[0200] The second terminal portion (420) may extend from the first terminal portion (410). The second terminal portion (420) may protrude laterally from the first terminal portion (410). The second terminal portion (420) may be positioned between the weld portion (300a) and the first terminal portion (410). The second terminal portion (420) may be positioned relatively closer to the weld portion (300a) than to the first terminal portion (410).

[0201] The bus bar (30) can be seated on the upper surface of the second terminal portion (420). The bus bar (30) and the second terminal portion (420) can be joined integrally by laser welding or the like.

[0202] The second terminal portion (420) according to the present embodiment may include a first terminal surface (421), a second terminal surface (422), and a third terminal surface (423).

[0203] The first terminal surface (421) may be positioned to face the cap plate (300). The first terminal surface (421) may be exemplified as the lower surface of a second terminal portion (420) positioned to face the second plate surface (320) of the cap plate (300). The first terminal surface (421) may come into contact with the gasket (500).

[0204] The second terminal surface (422) may be spaced apart from the first terminal surface (421) along the first direction. The second terminal surface (422) may be positioned to face the external space of the case (100). The second terminal surface (422) may be exemplified as the upper surface of the second terminal portion (420) positioned to face in a direction opposite to the first terminal surface (421). The second terminal surface (422) may be non-contact with the gasket (500).

[0205] The third terminal surface (423) can connect the first terminal surface (421) and the second terminal surface (422). The third terminal surface (423) can be positioned to face the direction in which the plate protrusion (340) of the cap plate (300) is located. The third terminal surface (423) can be exemplified as the outer surface of the second terminal portion (420) which is positioned to intersect the first terminal surface (421) and the second terminal surface (422). The third terminal surface (423) can be in contact with the gasket (500).

[0206] In this embodiment, a terminal groove portion (421a) may be provided on the other first terminal surface (421). The terminal groove portion (421a) may have the shape of a groove formed by being recessed from the first terminal surface (421) toward the second terminal surface (422). The terminal groove portion (421a) may be arranged to surround the gasket (500). A portion of the gasket (500) may be received inside the terminal groove portion (421a).

[0207] The width (W2) of the first terminal surface (421), excluding the width (W1) of the terminal groove portion (421a), may be 0.7 mm or more and 0.9 mm or less. The depth (D) of the terminal groove portion (421a) may be 0.7 mm or more and 0.9 mm or less.

[0208] By configuring the terminal groove portion (421a) formed concavely on the first terminal surface (421), the contact area with the gasket (500) can be increased, thereby improving the bonding strength of the gasket (500) during injection molding of the gasket (500).

[0209] The connecting portion (430) can connect the first terminal portion (410) and the second terminal portion (420). The connecting portion (430) can be positioned between the first terminal portion (410) and the second terminal portion (420) and connected to the first terminal portion (410) and the second terminal portion (420).

[0210] The connecting portion (430) extends along the first direction from the upper surface of the first terminal portion (410), and the second terminal portion (420) may extend from the connecting portion (430) in the direction where the plate protrusion (340) of the cap plate (300) is located.

[0211] The connecting portion (430) according to the present embodiment may be provided with an inclined surface (431). The inclined surface (431) may be provided on the outer surface of the connecting portion (430) that contacts the gasket (500). The inclined surface (431) may be connected to the terminal groove portion (421a). The inclined surface (431) may be formed to be inclined upward at a set angle toward the terminal groove portion (421a). It may guide the inflow of resin so that resin flows into the terminal groove portion (421a) during injection molding of the gasket (500).

[0212] The terminals (400) according to the present embodiment may be provided as a pair. The pair of terminals (400) may be arranged spaced apart at a set interval along the second direction. The pair of terminals (400) may be arranged facing each other along the second direction with the vent hole (301) in between.

[0213] The lower surfaces of a pair of terminals (400) can be positioned to face each other with different plate holes (304). A pair of terminals (400) can be positioned to face each other along a first direction with a first electrode tab (240) and a second electrode tab (250) through different plate holes (304).

[0214] A pair of terminals (400) can each be individually connected to the first electrode (210) and the second electrode (220) of the electrode assembly (200). Accordingly, the pair of terminals (400) can each function as the positive terminal and the negative terminal of the secondary battery (2). For example, the pair of terminals (400) can each be electrically connected to the first electrode (210) and the second electrode (220) by a first connecting member (401) and a second connecting member (402).

[0215] The first connecting member (401) may be positioned between the electrode assembly (200) and the cap plate (300). The first connecting member (401) may connect the terminal (400) positioned facing the first electrode tab (240) among a pair of terminals (400) to the first electrode tab (240).

[0216] The first connecting member (401) may be formed of a conductive material. The first connecting member (401) may be formed of the same material as the terminal (400).

[0217] The first connecting member (401) according to the present embodiment may include a first current collection plate (401a), a first tap connecting part (401b), and a first terminal connecting part (401c).

[0218] The first current collector plate (401a) may be positioned between the first electrode tab (240) and the first plate surface (310) of the cap plate (300). The lower surface of the first current collector plate (401a) may be positioned to face along the first direction the space formed between a pair of first electrode tabs (240) positioned adjacently along the second direction.

[0219] The upper surface of the first current collection plate (401a) can be positioned to face one of the pair of terminals (400) through the plate hole (304).

[0220] The first tap connection part (401b) extends from the first current collection plate (401a) and can be connected to the first electrode tap (240).

[0221] The first tap connection portion (401b) according to the present embodiment may be provided as a pair. The pair of first tap connection portions (401b) may extend from both ends of the first current collection plate (401a) along the second direction and the direction opposite to the second direction.

[0222] Each first tap connection (401b) may be positioned to face each other along a first direction with different first electrode tabs (240). Each first tap connection (401b) may individually contact the end surface of different first electrode tabs (240). The first electrode tabs (240) and the first tap connection (401b) may be joined together by laser welding.

[0223] The first terminal connection part (401c) extends from the first current collection plate (401a) and can be connected to the terminal (400).

[0224] The first terminal connection part (401c) according to the present embodiment may have the shape of a column extending along a first direction from the upper surface of the first current collection plate (401a) facing the plate hole (304). The upper end of the first terminal connection part (401c) penetrates the plate hole (304) and may come into contact with the lower surface of a terminal positioned facing the first electrode tab (240).

[0225] The cross-sectional shape of the first terminal connection part (401c) can be designed to have various shapes, such as an ellipse or a polygon, in addition to the circular shape shown in the drawing. The upper part of the first terminal connection part (401c) can be joined to the lower surface of the first terminal part (410) by laser welding.

[0226] The second connecting member (402) may be positioned between the electrode assembly (200) and the cap plate (300). The second connecting member (402) may connect the terminal (400) positioned facing the second electrode tab (250) among a pair of terminals (400) to the second electrode tab (250).

[0227] The second connecting member (402) may be formed of a conductive material. The second connecting member (402) may be formed of the same material as the terminal (400). The first connecting member (401) and the second connecting member (402) may be arranged at a set interval along the second direction.

[0228] The second connecting member (402) according to the present embodiment may include a second current collection plate (402a), a second tap connection part (402b), and a second terminal connection part (402c).

[0229] The second current collector plate (402a) may be positioned between the second electrode tab (250) and the first plate surface of the cap plate (300). The lower surface of the second current collector plate (402a) may be positioned to face along the first direction the space formed between a pair of second electrode tabs (250) positioned adjacently along the second direction.

[0230] The upper surface of the second current collection plate (402a) can be positioned to face the other terminal (400) of the pair of terminals (400) through the plate hole (304).

[0231] The second tap connection part (402b) extends from the second current collection plate (402a) and can be connected to the second electrode tap (250).

[0232] The second tap connection part (402b) according to the present embodiment may be provided as a pair. The pair of second tap connection parts (402b) may extend from both ends of the second current collection plate (402a) along the second direction and the direction opposite to the second direction.

[0233] Each second tap connection (402b) may be positioned to face each other along a first direction with different second electrode tabs (250). Each second tap connection (402b) may individually contact the end surface of different second electrode tabs (250). The second electrode tabs (250) and the second tap connection (402b) may be joined together by laser welding.

[0234] The second terminal connection part (402c) extends from the second current collection plate (402a) and can be connected to the terminal (400).

[0235] The second terminal connection part (402c) according to the present embodiment may have the shape of a column extending along a first direction from the upper surface of the second current collection plate (402a) facing the plate hole (304). The upper end of the second terminal connection part (402c) penetrates the plate hole (304) and may come into contact with the lower surface of the terminal (400) positioned facing the second electrode tab (250).

[0236] The cross-sectional shape of the second terminal connection part (402c) can be designed to have various shapes, such as an ellipse or a polygon, in addition to the circular shape shown in the drawing. The upper part of the second terminal connection part (402c) can be joined to the lower surface of the first terminal part (410) by laser welding.

[0237] A gasket (500) may be placed between the cap plate (300) and the terminal (400) according to the present embodiment.

[0238] The gasket (500) can function as a component for electrically insulating the cap plate (300) and the terminal (400) from each other. The gasket (500) can be formed from an insulating material such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET) rubber, etc.

[0239] The gasket (500) may be provided as a pair. One of the gaskets (500) of the pair may be placed between the terminal (400) connected to the first connecting member (401) and the cap plate (300).

[0240] The remaining gasket (500) of the pair of gaskets (500) may be placed between the terminal (400) connected to the second connecting member (402) and the cap plate (300). The gasket (500) may be formed by injection molding.

[0241] Hereinafter, the gasket (500) positioned between the terminal (400) connected to the first connecting member (401) and the cap plate (300) among a pair of gaskets (500) will be described as an example. The description of the gasket (500) described below may be applied in the same way to the gasket (500) positioned between the terminal (400) connected to the second connecting member (402) and the cap plate (300).

[0242] The gasket (500) according to the present embodiment may include a gasket body part (510), a first gasket extension part (520), a second gasket extension part (530), and a third gasket extension part (540).

[0243] The gasket body part (510) forms the central exterior of the gasket (500) and can support the first gasket extension part (520), the second gasket extension part (530), and the third gasket extension part (540).

[0244] The gasket body portion (510) according to the present embodiment may be disposed between the terminal (400) and the electrode assembly (200). The gasket body portion (510) may penetrate the cap plate (300) through the plate hole (304).

[0245] The central axis of the gasket body portion (510) may be positioned to be on the same axis as the central axis of the terminal (400). A hollow that penetrates the gasket body portion (510) in a first direction may be formed in the central part of the gasket body portion (510). Accordingly, the first terminal connection portion (401c) of the first connection member (401) and the second terminal connection portion (402c) of the second connection member (402) may come into contact with the lower surface of the first terminal portion (410) through the hollow of the gasket body portion (510).

[0246] The outer surface of the gasket body part (510) can be in close contact with the inner surface of the cap plate (300) that surrounds the plate hole (304).

[0247] The first gasket extension portion (520) may extend from the gasket body portion (510) to the inside of the cap plate (300), that is, into the internal space of the case (100). The first gasket extension portion (520) may be positioned to face the first plate surface (310) of the cap plate (300).

[0248] The first gasket extension portion (520) according to the present embodiment may extend from the lower end of the gasket body portion (510) in a direction parallel to the first plate surface (310). The first gasket extension portion (520) may be in close contact with the first plate surface (310). The end of the first gasket extension portion (520) may be inserted into the plate groove portion (330).

[0249] The second gasket extension (530) may extend from the gasket body (510) to the outside of the cap plate (300). The second gasket extension (530) may be positioned to face the plate protrusion (340) of the cap plate (300). The second gasket extension (530) may be in close contact with the side of the plate protrusion (340).

[0250] The third gasket extension (540) may extend from the second gasket extension (530) to the outside of the cap plate (300). The third gasket extension (540) may extend from the second gasket extension (530) along the first direction.

[0251] The third gasket extension (540) may be positioned facing the second terminal portion (420). The third gasket extension (540) may be in close contact with the third terminal surface (422) of the second terminal portion (420). The third gasket extension (540) may be positioned at a set distance from the plate protrusion (340) so as not to come into contact with the plate protrusion (340).

[0252] The distance (S) between the weld portion (300a) and the third gasket extension portion (540) according to the present embodiment may be formed to be greater than the thickness of the terminal (400). The distance (S) between the weld portion (300a) and the third gasket extension portion (540) may be 2.5 mm or more and 4 mm or less. If the distance (S) between the weld portion (300a) and the third gasket extension portion (540) is less than 2.5 mm, the third gasket extension portion (540) may be damaged by welding heat when welding the cap plate (300) to the case (100).

[0253] The ratio of the distance (S) between the welded portion (300a) and the third gasket extension portion (540) to the width of the cap plate (300) according to the present embodiment may be 8.9 or more and 16.1 or less. The width (W3) of the third gasket extension portion may be 0.7 mm or more and 0.9 mm or less.

[0254] FIG. 7 is a partial cross-sectional view schematically showing the configuration of a secondary battery according to another embodiment of the present invention, and FIG. 8 is an enlarged view of FIG. 7.

[0255] Referring to FIGS. 7 and 8, a secondary battery (20) according to another embodiment of the present invention may include a case (100), an electrode assembly (200), a cap plate (300), a terminal (400), and a gasket (500).

[0256] In describing a secondary battery (20) according to another embodiment of the present invention, another embodiment of a terminal (400) not described in the secondary battery (20) according to one embodiment of the present invention will be described.

[0257] For the remaining configuration of the secondary battery (20) according to another embodiment of the present invention, the description of the secondary battery (20) according to one embodiment of the present invention may be applied as is.

[0258] The terminal (400) may include a first terminal portion (410), a second terminal portion (420), and a connection portion (430).

[0259] The connecting portion (430) according to the present embodiment may be provided with a stepped surface (432). The stepped surface (432) may be formed steppedly on the outer surface of the connecting portion (430) that contacts the gasket (500).

[0260] The stepped surface (432) according to the present embodiment may include a first stepped surface (432a) and a second stepped surface (432b).

[0261] The first stepped surface (432a) can be connected to the first terminal portion (410). The first stepped surface (432a) can be formed along the first direction on the outer surface of the first terminal portion (410). The first stepped surface (432a) can be positioned to face the plate protrusion (340) of the cap plate (300).

[0262] The second stepped surface (432b) is connected to the second terminal portion (420) and can be arranged to intersect with the first stepped surface (432a). The second stepped surface (432b) can be arranged to face the electrode assembly (200). The second stepped surface (432b) can be connected to the terminal groove portion (421a).

[0263] By configuring the stepped surface (432) formed in a stepped manner on the connecting portion (430), the contact area with the gasket (500) can be increased, thereby improving the bonding strength of the gasket (500) during injection molding of the gasket (500). Additionally, the inflow of resin can be guided so that resin flows into the terminal groove portion (421a) during injection molding of the gasket (500).

[0264] Hereinafter, a method for manufacturing a secondary battery according to one embodiment of the present invention will be described.

[0265] FIG. 9 is a flowchart schematically illustrating a method for manufacturing a secondary battery according to one embodiment of the present invention, and FIGS. 10 to 13 are diagrams schematically illustrating a process for manufacturing a secondary battery according to one embodiment of the present invention.

[0266] Referring to FIGS. 9 to 13, first, a cap plate (300) and a terminal (400) are placed between the first mold (50) and the second mold (60) (S100).

[0267] In this embodiment, the first mold (50) and the second mold (60) can be exemplified by various types of molds commonly used in injection molding processes.

[0268] A first cavity (C1) may be formed in the first mold (50) by being concavely formed from one surface of the first mold (50) facing the second mold (60). A second cavity (C2) may be formed in the second mold (60) by being concavely formed from one surface of the second mold (60) facing the first mold (50).

[0269] In step S100, the first mold (50) and the second mold (60) can be arranged at a set interval along the first direction.

[0270] In step S100, the cap plate (300) and the terminal (400) can be seated on the second mold (60).

[0271] In step S100, the cap plate (300) and the terminal (400) may be spaced apart by a predetermined distance along the first direction on the second mold (60).

[0272] After step S100, the first mold (50) can be moved toward the second mold (60) to form a cavity (C) (S200).

[0273] In step S200, the first mold (50) can be moved toward the second mold (60) in the opposite direction of the first direction.

[0274] In step S200, as the first mold (50) moves more than a set distance in the opposite direction of the first direction toward the second mold (60), the terminal (400) can be inserted into the interior of the first cavity (C1). The shape of the cavity (C) may have a shape corresponding to the shape of the gasket (500).

[0275] After step S200, resin (R) is injected into the cavity (C) to form a gasket (500) (S300).

[0276] In step S300, the resin (R) can be injected in a liquid state into the cavity (C) through an injection pipe formed in the first mold (50) or the second mold (60). The resin (R) injected into the cavity (C) hardens into a solid state and can form a gasket (500).

[0277] The above process can be performed sequentially for a pair of terminals (400), or alternatively, simultaneously.

[0278] Afterwards, the first mold (50) is moved in the first direction and separated from the second mold (60), and the cap plate (300) and terminal (400) mutually joined by the gasket (500) can be separated from between the first mold (50) and the second mold (60).

[0279] Afterwards, the cap plate (300) is coupled to the case (100), and a pair of terminals (400) can be joined to the first connecting member (401) and the second connecting member (402), respectively.

[0280] 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.

[0281] Therefore, the technical scope of protection of the present invention should be determined by the following patent claims. Explanation of the symbols

[0282] 10: Housing 11: Housing body 12: Housing cover 20: Secondary battery 30: Bus Bar 40: Bus bar holder 50: 1st mold 60: Second mold 100: Case 110: Bottom part 120: Front 130: Rear 140: First side section 150: Second side section 160: Open section 200: Electrode assembly 210: First electrode 211: First active material layer 212: 1st Department of Indefinite Expenses 220: Second electrode 221: Second active material layer 222: 2nd Department of Indefinite Service 230: Separator 240: First electrode tab 241: First tab member 250: Second electrode tab 251: Second tab member 300: Cap Plate 300a: Welded part 301: Vent hole 302: Vent 303: Electrolyte inlet 304: Plate hole 305: Insulation plate 310: First plate surface 320: Second plate surface 330: Plate groove 340: Plate protrusion 400: Terminal 410: First terminal section 420: Second terminal section 421: First terminal face 421a: Terminal groove 422: Second terminal face 423: Third terminal face 430: Connection 431: Slope 432: Step surface 432a: First step surface 432b: Second step surface 500: Gasket 510: Gasket body 520: First gasket extension 530: Second gasket extension 540: Third gasket extension C: Cavity C1: 1st cavity C2: 2nd cavity

Claims

Claim 1 A secondary battery comprising: a case; an electrode assembly accommodated in the case; a cap plate welded to the case to form a welded portion and having a pair of terminals having different polarities; and a gasket disposed between the cap plate and the terminals; wherein the terminals include: a first terminal portion connected to the electrode assembly; and a second terminal portion extending from the first terminal portion and disposed between the welded portion and the first terminal portion. Claim 2 A secondary battery according to claim 1, wherein the second terminal portion comprises: a first terminal surface facing the cap plate; a second terminal surface arranged to face in a direction opposite to the first terminal surface; and a third terminal surface connecting the first terminal surface and the second terminal surface and arranged to intersect the first terminal surface and the second terminal surface. Claim 3 A secondary battery according to paragraph 2, characterized in that the first terminal surface is provided with a terminal groove portion formed by being recessed toward the second terminal surface and surrounding the gasket. Claim 4 A secondary battery according to claim 3, characterized in that the width of the first terminal surface, excluding the width of the terminal groove portion, is 0.7 mm or more and 0.9 mm or less. Claim 5 A secondary battery according to claim 3, characterized in that the depth of the terminal groove portion is 0.7 mm or more and 0.9 mm or less. Claim 6 A secondary battery according to paragraph 2, characterized in that the first terminal surface and the third terminal surface are in contact with the gasket, and the second terminal surface is not in contact with the gasket. Claim 7 A secondary battery according to claim 1, wherein the terminal further comprises a connecting portion connecting the first terminal portion and the second terminal portion. Claim 8 A secondary battery according to claim 7, characterized in that the connecting portion is provided with an inclined surface that contacts the gasket and is positioned at a set angle. Claim 9 A secondary battery according to claim 7, characterized in that the connecting portion is provided with a stepped surface in contact with the gasket. Claim 10 A secondary battery according to claim 9, wherein the stepped surface comprises: a first stepped surface connected to the first terminal portion; and a second stepped surface connected to the second terminal portion and arranged to intersect with the first stepped surface. Claim 11 A secondary battery according to claim 1, wherein the cap plate comprises: a first plate surface facing the electrode assembly; a second plate surface positioned to face in a direction opposite to the first plate surface; and a plate groove portion formed by being recessed into the first plate surface to surround the gasket. Claim 12 A secondary battery according to claim 11, wherein the cap plate further comprises a plate protrusion that protrudes from the second plate surface and at least a portion of which contacts the gasket. Claim 13 A secondary battery according to claim 12, wherein the gasket comprises: a gasket body portion penetrating the cap plate; a first gasket extension portion extending from the gasket body portion and positioned facing the first plate surface; a second gasket extension portion extending from the gasket body portion and positioned facing the plate protrusion; and a third gasket extension portion extending from the second gasket extension portion and positioned facing the second terminal portion. Claim 14 A secondary battery according to claim 13, wherein the third gasket extension is non-contacting with the plate protrusion. Claim 15 A secondary battery according to claim 13, characterized in that the distance between the welded portion and the third gasket extension portion is greater than the thickness of the terminal. Claim 16 A secondary battery according to claim 13, characterized in that the distance between the welded portion and the third gasket extension portion is 2.5 mm or more and 4 mm or less. Claim 17 A secondary battery according to claim 13, characterized in that the ratio of the distance between the welded portion and the third gasket extension portion to the width of the cap plate is 8.9 or more and 16.1 or less. Claim 18 A secondary battery according to claim 13, characterized in that the width of the third gasket extension is 0.7 mm or more and 0.9 mm or less. Claim 19 A method for manufacturing a secondary battery, characterized by comprising: a step of placing a cap plate and a terminal between a first mold and a second mold; a step of moving the first mold toward the second mold to form a cavity; and a step of injecting resin into the cavity to form a gasket. Claim 20 A battery module comprising: a housing; and a plurality of secondary batteries disposed inside the housing; wherein the secondary batteries comprise: a case; an electrode assembly accommodated in the case; a cap plate welded to the case to form a welded portion and having a pair of terminals having different polarities; and a gasket disposed between the cap plate and the terminals; wherein the terminals comprise: a first terminal portion connected to the electrode assembly; and a second terminal portion extending from the first terminal portion and disposed between the welded portion and the first terminal portion.

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