Secondary battery

Abstract

The present disclosure relates to a secondary battery, and the objective of the present disclosure is to provide a secondary battery capable of reducing internal resistance between a terminal and an electrode and improving sealing force between components. A secondary battery according to one embodiment comprises: an electrode assembly including a first electrode and a second electrode; a case electrically connected to the first electrode while accommodating the electrode assembly, one surface thereof having a hole formed therein and the other surface thereof being open; a cap plate covering the opening of the case; and a rivet inserted into the first hole, fixed to the case through a welding portion, and electrically connected to the second electrode. Drawing_references_to_be_translated

Description

secondary battery

[0001] The present disclosure relates to a secondary battery.

[0002] In general, the recent rapid proliferation of battery-powered electronic devices, such as mobile phones, laptops, and electric vehicles, has led to a rapid increase in demand for high-energy density and high-capacity secondary batteries. Accordingly, active research and development is underway to improve the performance of lithium secondary batteries.

[0003] A lithium secondary battery is a battery that includes a positive electrode and a negative electrode that contain active materials capable of intercalating and deintercalating lithium ions, and an electrolyte, and produces electrical energy through oxidation and reduction reactions when lithium ions are intercalated / deintercalated from the positive electrode and negative electrode.

[0004] Secondary batteries can be classified into cylindrical, pouch-shaped, coin-shaped, and square-shaped secondary batteries depending on the shape of their cases. Among these, cylindrical secondary batteries include a can, which is a cylindrical case with one side open, and a jelly-roll-shaped electrode assembly accommodated inside the can. In addition, cylindrical secondary batteries further include a cap plate that is coupled to the opening of the can to seal the can.

[0005] The above-described information disclosed in the background technology of this invention is only intended to improve understanding of the background of the present invention, and therefore may include information that does not constitute prior art.

[0006] One technical challenge that the present disclosure seeks to solve is to provide a secondary battery with reduced internal resistance.

[0007] Another technical challenge that the present disclosure seeks to address is to provide a secondary battery with enhanced adhesion between components.

[0008] However, the technical problems to be solved by the present disclosure are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0009] According to one embodiment of the present disclosure for solving the above-described problem, a secondary battery includes an electrode assembly including a first electrode and a second electrode, a case electrically connected to the first electrode while housing the electrode assembly, having a first hole formed on one surface and an open surface on the other surface, a cap plate covering the opening of the case, and a rivet inserted into the first hole and fixed to the case through a weld, and electrically connected to the second electrode.

[0010] For example, the secondary battery may further include a terminal plate positioned on one side of the case and positioned between the case and the rivet, and the terminal plate may have a second hole formed at a position corresponding to the first hole so that the rivet is inserted.

[0011] For example, the rivet may include a rivet body, an upper support portion extending outwardly from at least a portion of an outer circumferential surface on the upper side of the rivet body, and a lower support portion extending outwardly from at least a portion of an outer circumferential surface on the lower side of the rivet body, wherein the rivet body is inserted into the second hole, and the upper support portion may be joined to an upper surface of the terminal plate through the welding portion.

[0012] For example, the weld may include one or more weld lines formed on the interface between the upper support and the terminal plate.

[0013] For example, the weld may include at least one welding point formed on an interface between the upper support and the terminal plate.

[0014] For example, the weld may include one or more weld lines and one or more weld points formed spaced apart from each other on the interface between the upper support and the terminal plate.

[0015] For example, the terminal plate may further include a catch formed by extending from an outer surface of one side of the second hole and corresponding to the shape of the upper support portion.

[0016] For example, the upper support portion may be formed with a first radius, and the lower support portion may be formed with a second radius that is equal to or greater than the first radius.

[0017] For example, the secondary battery may further include an insulator positioned on the upper surface of the case and insulating between the rivet and the case.

[0018] For example, the secondary battery may further include at least one protrusion formed by protruding outward from at least a portion of the rivet.

[0019] According to another embodiment of the present disclosure for solving the above-described problem, a secondary battery includes a first component including a first polymer material, at least a portion of which is in contact with the first component, a second component including a second polymer material, and a third component including a metal material, at least a portion of which is in contact with the first component, wherein the first component may have a first roughness at a first contact surface in contact with the second component, and a second roughness that is less than or equal to the first roughness at a second contact surface in contact with the third component.

[0020] For example, the third configuration may include at least one of a case for accommodating an electrode assembly and a rivet inserted into a hole formed on one surface of the case and electrically connected to the electrode assembly, the first configuration may include a gasket positioned between the rivet and the case and sealing the case, and the second configuration may include at least one of an outer insulating layer provided between the rivet and the case and an inner insulating layer provided on a lower portion of the case to insulate between the electrode assembly and the case.

[0021] For example, the third configuration may include at least one of a case for accommodating an electrode assembly and a rivet inserted into a hole formed on one surface of the case and electrically connected to the electrode assembly, the first configuration may include an outer insulating layer provided between the rivet and the case, and the second configuration may include a gasket for sealing the rivet to the case.

[0022] For example, at the first interface, the second configuration may have a roughness in the same range as the roughness of the first configuration.

[0023] For example, the first roughness may be 0.01 to 2 um, and the second configuration at the first contact surface may have a roughness of 0.01 to 2 um.

[0024] For example, at the second contact surface, the third configuration may have a roughness greater than the second roughness.

[0025] For example, the first roughness may be 0.01 to 2 um, and the third configuration at the second contact surface may have a roughness of 0.1 um to 20 um.

[0026] According to another embodiment of the present disclosure for solving the above-mentioned technical problem, a secondary battery includes a case for accommodating an electrode assembly, a rivet inserted into a hole formed on one surface of the case and electrically connected to the electrode assembly, and a gasket positioned between the rivet and the case and sealing the case, wherein the gasket may include a first region and a second region having a roughness less than or equal to the first region.

[0027] For example, the first region may further include at least one of an outer insulating layer provided between the rivet and the case and an inner insulating layer provided on the lower portion of the case to insulate between the electrode assembly and the case, and the first region may form a first contact surface that is in contact with at least one of the outer insulating layer and the inner insulating layer, and at least one of the outer insulating layer and the inner insulating layer at the first contact surface may have a roughness in the same range as that of the first region.

[0028] For example, the second region may form a second contact surface that contacts at least one of the rivet and the case, and at the second contact surface, at least one of the rivet and the case may have a roughness greater than that of the second region.

[0029] For example, in the second contact surface, the second region may have a roughness of 0.01 to 2 um, and at least one of the rivet and the case may have a roughness of 0.1 to 20 um.

[0030] According to one embodiment of the present disclosure, the internal resistance between the terminal and electrode of a secondary battery can be reduced.

[0031] According to one embodiment of the present disclosure, the adhesive strength between components constituting a secondary battery can be strengthened. In addition, the sealing effect of the secondary battery can be enhanced, and the mechanical stability can be increased.

[0032] However, the effects that can be obtained through the present disclosure are not limited to the effects described above, and other technical effects not mentioned will be clearly understood by those skilled in the art from the description of the invention described below.

[0033] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0034] FIG. 1 is a perspective view schematically illustrating an example of a configuration of a battery pack including a secondary battery according to one embodiment of the present disclosure.

[0035] Figure 2 is a plan view schematically showing part of the configuration of the battery pack of Figure 1.

[0036] FIG. 3 is a perspective view schematically illustrating an example of a configuration of a secondary battery according to one embodiment of the present disclosure.

[0037] Figure 4 is a schematic cross-sectional view of the secondary battery of Figure 3.

[0038] Fig. 5 is a cross-sectional view schematically showing a part of the configuration of the secondary battery of Fig. 3.

[0039] Figure 6 is an example of a cross-sectional view showing an enlarged portion of X in Figure 5.

[0040] Fig. 7 is a plan view illustrating a weld according to one embodiment of the present disclosure.

[0041] FIG. 8 is another example of a cross-sectional view of the upper side of a secondary battery according to one embodiment of the present disclosure.

[0042] Figure 9 is a graph showing the change in internal resistance of a case over time in a secondary battery.

[0043] Fig. 10 is a cross-sectional view showing another example of an enlarged portion X of Fig. 5.

[0044] FIG. 11 is a drawing schematically showing an example of the first contact surface described above with reference to FIG. 10.

[0045] Fig. 12 is a schematic drawing showing another example of the first contact surface described above with reference to Fig. 10.

[0046] FIG. 13 is a schematic drawing showing an example of the second contact surface in the example described above with reference to FIG. 10.

[0047] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their typical or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only 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 modified examples may exist as substitutes for them at the time of filing this application.

[0048] Additionally, when used herein, the terms "comprise", "include" and / or "comprising", "including" specify the presence of stated features, numbers, steps, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and / or groups thereof.

[0049] Additionally, to facilitate understanding of the invention, the attached drawings are not drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0050] The statement that two compared objects are "identical" means "substantially identical." Therefore, "substantially identical" may include deviations considered low in the art, such as deviations of less than 5%. Furthermore, uniformity of a parameter over a given region may imply uniformity on average.

[0051] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0052] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0053] Any configuration being placed "on (or under)" or "above (or below)" a component may mean not only that any configuration is placed in contact with the upper surface (or lower surface) of said component, but also that other configurations may intervene between said component and any configuration placed on (or below) said component.

[0054] Additionally, when a component is described as being "on," "connected to," or "coupled to" another component, it should be understood that the components may be directly connected or coupled to one another, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through other components.

[0055] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Furthermore, the use of "may" when describing embodiments of the present disclosure refers 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 list as a whole and do not modify individual elements in the list.

[0056] When reference is made throughout the specification to “A and / or B,” this means A, B, or A and B, unless otherwise stated, and when reference is made to “C through D,” this means C or more and D or less, unless otherwise stated.

[0057] When phrases such as "at least one of A, B, and C," "at least one of A, B, or C," "at least one selected from the group A, B, and C," or "at least one selected from A, B, and C," are used to specify a list of elements A, B, and C, the phrases can refer to any suitable combination.

[0058] The term "use" may be considered synonymous with the term "utilize." As used herein, the terms "substantially," "about," and similar terms are used as terms of approximation rather than degrees, and are intended to take into account inherent variations in measured or calculated values ​​that would be recognized by those skilled in the art.

[0059] Although terms such as first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and / or sections, 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. Thus, a first element, component, region, layer, or section discussed below could also be termed a second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0060] For ease of description, spatially relative terms such as "beneath," "below," "lower," "above," "upper," and the like may be used herein to describe the relationship of one element or feature to another element(s) or feature(s) as depicted in the drawings. It will be understood that spatially relative positions encompass 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 drawings is turned over, an element described as "beneath" or "lower" another element would be understood to be "above" or "upper" the other element. Thus, the term "beneath" can encompass both the above and below orientations.

[0061] The terminology used herein is for the purpose of describing embodiments of the present disclosure and is not intended to be limiting of the present disclosure.

[0062]

[0063] FIG. 1 is a perspective view schematically illustrating an example of a configuration of a battery pack including a secondary battery according to one embodiment of the present disclosure. FIG. 2 is a plan view schematically illustrating a portion of the configuration of the battery pack of FIG. 1. Referring to FIGS. 1 and 2, the battery pack may include a housing (1), a secondary battery (2), and a bus bar (3).

[0064] The housing (1) forms the outline of a battery pack and can provide a space in which a plurality of secondary batteries (2) can be accommodated. The housing (1) can include a housing body (11) and a cover (12).

[0065] The housing body (11) can be formed to have the shape of a box with an empty interior and one open side. The planar shape of the housing body (11) is not limited to the square shape illustrated in Fig. 1, and can be designed to have various shapes such as a polygon, circle, or oval.

[0066] The cover (12) is coupled to the housing body (11) and can close the internal space of the housing body (11). For example, the cover (12) is formed to have a general plate shape and can be positioned to face an open side of the housing body (11). The cover (12) can be fixed to the housing body (11) by various types of coupling methods such as bolting, welding, and fitting.

[0067] The secondary battery (2) can function as a unit structure that stores and supplies power in a battery pack. The secondary battery (2) can be provided in multiple units. The multiple secondary batteries (2) can be arranged in various patterns, such as a grid shape or a zigzag shape, inside the housing (1). The multiple secondary batteries (2) can be arranged in parallel with each other. The number of secondary batteries (2) can be designed in various ways depending on the size, shape, etc. of the housing (1). The detailed configuration of the secondary battery (2) will be described later.

[0068] The bus bar (3) can electrically connect a plurality of secondary batteries (2). The plurality of secondary batteries (2) can be connected in series and / or in parallel by the bus bar (3). For example, the bus bar (3) can connect secondary batteries (2) arranged in the same row inside the housing (1) in parallel with each other, and connect secondary batteries (2) arranged in two adjacent rows in series with each other. The bus bar (3) can be formed of an electrically conductive material such as copper, aluminum, or nickel.

[0069] According to one implementation example, the busbar (3) may include a main busbar (31), a first branch busbar (32) and a second branch busbar (33).

[0070] The main bus bar (31) can be arranged between rows of neighboring secondary batteries (2). The main bus bar (31) can be provided in multiple numbers. The main bus bar (31) can extend in a straight line between rows of secondary batteries (2). However, this is exemplary, and the main bus bar (31) can also be regularly bent in a zigzag shape between rows of secondary batteries (2). A plurality of main bus bars (31) can be individually arranged between different rows of neighboring secondary batteries (2). The plurality of main bus bars (31) can be electrically interconnected.

[0071] The first branch bus bar (32) can extend from the main bus bar (31) toward the rivet of the secondary battery (2) described later. The first branch bus bar (32) can be mechanically and electrically connected to the rivet by laser welding, ultrasonic welding, or the like.

[0072] The second branch bus bar (33) can extend from the main bus bar (31) toward the case of the secondary battery (2) described later. The second branch bus bar (33) can be mechanically and electrically connected to the case by laser welding, ultrasonic welding, or the like.

[0073] FIG. 3 is a perspective view schematically illustrating an example of the configuration of a secondary battery according to one embodiment of the present disclosure. FIG. 4 is a schematic cross-sectional view of the secondary battery of FIG. 3. And FIG. 5 is a perspective cross-sectional view schematically illustrating a portion of the configuration of the secondary battery of FIG. 3. The secondary battery (100) illustrated in FIGS. 3 to 5 may be an example of the secondary battery (2) illustrated in FIGS. 1 and 2.

[0074] Referring to FIGS. 3 to 5, a secondary battery (100) includes an electrode assembly (10) and a case (20) that accommodates the electrode assembly (10). The case (20) may have an open side, and the secondary battery (100) may include a cap plate (60) that covers the opening of the case (20). In addition, the secondary battery (100) may include a rivet (30) that is inserted into a hole formed on the other side of the case (20) and is electrically connected to the electrode assembly (10). The components of the secondary battery (100) are not limited to the components illustrated in FIGS. 3 to 5, and may further include other components in addition to the components illustrated in FIGS. 3 to 5.

[0075] Hereinafter, the secondary battery (100) is described as a cylindrical battery as a lithium ion secondary battery as an example. However, the present embodiment is not limited thereto, and the secondary battery (100) may be a lithium polymer battery or a square battery.

[0076] An electrode assembly (10) can function as a unit structure that performs charging and discharging operations of power in a secondary battery (100). The electrode assembly (10) includes a first electrode and a second electrode. The first electrode is a positive electrode or a negative electrode. The second electrode is a negative electrode or an positive electrode and has a different polarity from the first electrode.

[0077] In addition, the electrode assembly (10) may further include a separator between the first electrode and the second electrode. The electrode assembly (10) may prevent the first electrode and the second electrode from contacting each other, thereby preventing a short circuit from occurring between the first electrode and the second electrode. Accordingly, the electrode assembly (10) may be formed by stacking the first electrode, the second electrode, and the separator provided between the first electrode and the second electrode.

[0078] At this time, when the electrode assembly (10) forms a cylindrical shape, the laminated structure including the first electrode, the second electrode, and the separator can be wound to form a jelly roll. For example, the electrode assembly (10) can have a form wound in a clockwise or counterclockwise direction with the winding axis as the center. Here, the winding axis can mean a straight line passing through the center of the electrode assembly (10). When viewed from above, the planar shape of the electrode assembly (10) can be designed to have various shapes such as an oval or a polygon in addition to a circle.

[0079] A detailed description of each component of the electrode assembly (10) is as follows.

[0080]

[0081] positive electrode active material

[0082] A compound capable of reversible intercalation and deintercalation of lithium (a lithiated intercalation compound) can be used as a cathode active material. Specifically, one or more of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used.

[0083] The above composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include lithium nickel-based oxide, lithium cobalt-based oxide, lithium manganese-based oxide, lithium iron phosphate-based compound, cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0084] As an example, a compound represented by any one of the following chemical formulas may be used. LiaA1-bXbO2-cDc(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiaMn2-bXbO4-cDc(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiaNi1-b-cCobXcO2-αDα(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); LiaNi1-b-cMnbXcO2-αDα(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); LiaNibCocL1dGeO2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); LiaNiGbO2(0.90≤a≤1.8, 0.001≤b≤0.1); LiaCoGbO2(0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn1-bGbO2 (0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn2GbO4 (0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn1-gGgPO4(0.90≤a≤1.8, 0≤g≤0.5); Li(3-f)Fe2(PO4)3(0≤f≤2); LiaFePO4(0.90≤a≤1.8).

[0085] In the chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; and L1 is Mn, Al, or a combination thereof.

[0086] For example, the cathode active material may be a high-nickel cathode active material in which the nickel content is 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less, based on 100 mol% of metals excluding lithium in the lithium transition metal composite oxide. The high-nickel cathode active material can realize high capacity and thus can be applied to high-capacity, high-density lithium batteries.

[0087] anode

[0088] A positive electrode for a secondary battery (100) may include a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer includes a positive electrode active material and may further include a binder and / or a conductive material.

[0089] For example, the anode may further include an additive that can act as a sacrificial anode.

[0090] The content of the positive electrode active material may be 90 wt% to 99.5 wt% with respect to 100 wt% of the positive electrode active material layer, and the contents of the binder and conductive material may be 0.5 wt% to 5 wt%, respectively, with respect to 100 wt% of the positive electrode active material layer.

[0091] The above binder serves to adhere the positive electrode active material particles well to each other and also to adhere the positive electrode active material well to the current collector. Representative examples of the binder include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0092] The conductive material is used to provide conductivity to the electrode, and any material that does not cause chemical changes and is electronically conductive can be used in the battery. Examples of the conductive material include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials containing copper, nickel, aluminum, silver, etc. and in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0093] Al may be used as the above current collector, but is not limited thereto.

[0094] Negative active material

[0095] The negative electrode active material includes 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.

[0096] The material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0097] As the above lithium metal alloy, an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn can be used.

[0098] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-Q alloy (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 a combination thereof. The Sn-based negative electrode active material may be Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0099] The silicon-carbon composite may be a composite of silicon and amorphous carbon. In one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the composite may include secondary particles (cores) in which silicon primary particles are assembled, and an amorphous carbon coating layer (shell) positioned on the surface of the secondary particles. The amorphous carbon may also be positioned between the silicon primary particles, such that, for example, the silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed and present in an amorphous carbon matrix.

[0100] The silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core.

[0101] The above Si-based negative electrode active material or Sn-based negative electrode active material can be used in a mixture with a carbon-based negative electrode active material.

[0102] cathode

[0103] A negative electrode for a secondary battery (100) includes a current collector and a negative electrode active material layer positioned on the current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder and / or a conductive material.

[0104] For example, the negative electrode active material layer may include 90 to 99 wt% of the negative electrode active material, 0.5 to 5 wt% of the binder, and 0 to 5 wt% of the conductive material.

[0105] The above binder serves to adhere the negative electrode active material particles well to each other and also to adhere the negative electrode active material well to the current collector. The binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0106] Examples of the non-aqueous binder include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or combinations thereof.

[0107] The above-mentioned aqueous binder may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluoroelastomer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0108] When using an aqueous binder as the above-mentioned negative electrode binder, a cellulose-based compound capable of imparting viscosity may be further included. The cellulose-based compound may be a mixture of one or more of carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or an alkali metal salt thereof. The alkali metal may be Na, K, or Li.

[0109] The above dry binder is a polymeric material capable of being fiberized, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0110] The conductive material is used to provide conductivity to the electrode, and any material that does not cause chemical changes and is electronically conductive can be used in the battery. Specific examples 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 powder or metal fibers, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0111] The negative electrode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and a combination thereof.

[0112] membrane

[0113] Depending on the type of secondary battery (100), a separator may be present between the positive electrode (10) and the negative electrode (20). As such a separator, a multilayer film of two or more layers of polyethylene, polypropylene, polyvinylidene fluoride, or these may be used, and of course, a mixed multilayer film 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.

[0114] The above separator may include a porous substrate and a coating layer including an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0115] The above porous substrate may be a polymer film formed of any one polymer selected from polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyacetal, polyamide, polyimide, polycarbonate, polyether ketone, polyarylether ketone, 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 thereof.

[0116] The organic material may include a polyvinylidene fluoride polymer or a (meth)acrylic polymer.

[0117] The above inorganic material may include inorganic particles selected from, but not limited to, Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0118] The organic and inorganic substances may be mixed and present in one coating layer, or a coating layer including an organic substance and a coating layer including an inorganic substance may be present in a laminated form.

[0119] The case (20) houses the electrode assembly (10). An electrolyte can be accommodated together with the electrode assembly (10) inside the case (20), and can be sealed by a cap assembly (60).

[0120] electrolyte

[0121] The electrolyte for a secondary battery (100) contains a non-aqueous organic solvent and a lithium salt.

[0122] The above non-aqueous organic solvent acts as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0123] The above non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent, an aprotic solvent, or a combination thereof.

[0124] Examples of the above carbonate solvents that can be used include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC).

[0125] Ester solvents that can be used include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolide, mevalonolactone, valerolactone, and caprolactone.

[0126] Examples of ether solvents that can be used include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and tetrahydrofuran. In addition, examples of ketone solvents that can be used include cyclohexanone. Examples of alcohol solvents that can be used include ethyl alcohol and isopropyl alcohol, and examples of aprotic solvents that can be used include nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane and 1,4-dioxolane; and sulfolanes.

[0127] The above non-aqueous organic solvents can be used alone or in combination of two or more.

[0128] In addition, when using a carbonate solvent, a cyclic carbonate and a chain carbonate can be mixed and used, and the cyclic carbonate and the chain carbonate can be mixed in a volume ratio of 1:1 to 1:9.

[0129] The above lithium salt is a substance that is dissolved in an organic solvent and acts as a source of lithium ions within the battery, enabling the basic operation of a lithium battery and promoting the movement of lithium ions between the positive and negative electrodes. Representative examples of lithium salts may include one or more selected from LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, LiN(CxF2x+1SO2)(CyF2y+1SO2) (x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate (LiDFOB), lithium bis(oxalato)borate (LiBOB).

[0130] The case (20) forms the general appearance of the secondary battery (100). The case (20) may have one of the upper and lower surfaces closed and the other open. Hereinafter, a case in which the upper surface of the case (20) is closed will be described as an example. Here, the upper and lower surfaces are based on the directions disclosed in FIGS. 3 to 5, and the positions of the upper and lower surfaces may be changed. More specifically, the case (20) may include an upper surface forming a cylindrical upper portion and a side surface connected to the outer surface of the upper surface and extending vertically from the upper surface to form a side portion.

[0131] The case (20) may have a hole (20h) formed on the upper surface. The hole (20h) may be formed while penetrating the upper surface of the case (20). The hole (20h) may be located at the center of the upper surface of the case (20). The hole (20h) may be formed, for example, in the vertically upward direction of the core portion of the electrode assembly (10).

[0132] When viewed from above, the shape of the hole (20h) may correspond to the shape of the rivet (30). For example, if the horizontal cross-section of the rivet (30) is circular, the shape of the hole (20h) may also be circular. In this case, the diameter of the cross-section of the hole (20h) may be larger than the diameter of the cross-section of the rivet (30).

[0133] The case (20) may be cylindrical and have an open bottom. The interior of the case (20) may be sealed when the opening of the case (20) is sealed by the cap plate (60). Accordingly, the case (20) can prevent electrolyte from leaking to the outside and protect the electrode assembly (10).

[0134] Meanwhile, the case (20) can be manufactured from, for example, steel, stainless steel, aluminum, aluminum alloy, a combination thereof, or an equivalent thereof.

[0135] The cap plate (60) can seal the case (20) while covering the opening of the case (20). At this time, the secondary battery (100) may further include a gasket (80, second gasket) to ensure more secure sealing of the case (20). The gasket (80) may be formed, for example, in a ring shape. The gasket (80) may surround the outer circumference of the cap plate (60) and be positioned between the cap plate (60) and the inner circumference of the case (20). Through this, the gasket (80) can prevent the electrolyte inside the secondary battery (100) from leaking out or air from penetrating into the case (20) through the interface between the cap plate (60) and the case (20).

[0136] The case (20) may have a beading portion (21) to fix the position of the cap plate (60) with respect to the opening of the case (20). For example, the beading portion (21) may be formed on the lower side of the case (20). The beading portion (21) may be formed so that the case (20) is recessed from the outside to the inside. The beading portion (21) may prevent the cap plate (60) from entering further into the case (20) from the opening of the case (20) through this recessed portion.

[0137] And the case (20) may further include a crimping portion (22) to fix the position of the cap plate (60) to the opening of the case (20). The crimping portion (22) may be formed by bending an end of a side surface of the case (20) toward the inside of the case (20). For example, the crimping portion (22) may be formed by bending toward the case (20) after the cap plate (60) is provided in the opening of the case (20). Through this, the cap plate (60) may be coupled to the opening of the case (20) without being separated from the opening.

[0138] The cap plate (60) can simultaneously function as a vent. For example, the cap plate (60) can include a groove (61). The groove (61) can be ruptured when the pressure or temperature inside the case (20) increases. When the groove (61) is ruptured, gas generated inside the case (20) can be released to the outside.

[0139] Meanwhile, the case (20) may be electrically connected to the electrode assembly (10) housed inside the case (20). For example, the case (20) may be electrically connected to a second electrode. The second electrode may be, for example, a cathode.

[0140] The secondary battery (100) may further include a second collector plate (70) positioned at the bottom of the electrode assembly (10) to electrically connect the case (20) and the second electrode. For example, the second collector plate (70) may be positioned between the electrode assembly (10) and the cap plate (60). In this case, the second collector plate (70) and the cap plate (60) may be insulated by a gasket (80). The second collector plate (70) may be, for example, a negative collector plate. The second collector plate (70) may be connected to a tab of the second electrode. In addition, the second collector plate (70) may be connected to the case (20). Through this, the case (20) may be electrically connected to the second electrode and may have the same polarity as the second electrode. That is, the case (20) may have a negative polarity.

[0141] The rivet (30) can be inserted into and joined to a hole (20h) formed on the upper surface of the case (20). The rivet (30) can be inserted into the hole (20h) and electrically connected to an electrode assembly (10) housed inside the case (20). For example, the rivet (30) can be electrically connected to a first electrode. The first electrode can be, for example, an anode.

[0142] The secondary battery (100) may further include a first collector plate (40) positioned on the upper side of the electrode assembly (10) to electrically connect the rivet (30) and the first electrode. The first collector plate (40) may be, for example, a positive collector plate. The first collector plate (40) may be connected to a tab of the first electrode. In addition, the first collector plate (40) may be connected to the rivet (30). Through this, the rivet (30) may be electrically connected to the first electrode and may have the same polarity as the first electrode. That is, the rivet (30) may have a positive polarity.

[0143] The rivet (30) may be formed of a conductive material to be electrically connected to the first electrode. For example, the rivet (30) may be formed of a metal. For example, the rivet (30) may be formed of aluminum (Al) or an alloy thereof.

[0144] The secondary battery (100) may further include an insulating layer (90). The insulating layer (90) may be provided on the first collector plate (40). The insulating layer (90) may prevent the first collector plate (40) and the case (20) from being electrically connected.

[0145] Through this configuration, the secondary battery (100) according to one embodiment of the present disclosure can provide a battery with improved capacity by eliminating the upper beading portion. Furthermore, the secondary battery (100) can resolve safety or financial issues that may arise when the secondary battery (100) explodes upward by having the cap plate (60) positioned at the bottom.

[0146] Figure 6 is an example of a cross-sectional view showing an enlarged portion of X in Figure 5.

[0147] As described above, the rivet (30) can be inserted into the first hole (20h) of the case (20) and connected to the first electrode. In this case, the rivet (30) can be fixed to the case (20) through a weld. By firmly fixing the rivet (30) to the case (20) through the weld, it is possible to suppress a decrease in the charge / discharge efficiency of the secondary battery (100) due to the rivet (30).

[0148] The rivet (30) allows the first electrode of the electrode assembly (10) to be electrically connected to the outside. For example, the rivet (30) can be connected to the first branch bus bar (32, see FIG. 2). Through this, the rivet (30) allows current to flow to the secondary battery (100). In addition, the rivet (30) can serve as a terminal for charging and discharging the secondary battery (100).

[0149] In this way, the rivet (30) needs to have as wide an area in contact with the outside as possible to ensure electrical connection with the outside. If the area in contact with the outside is narrow, the electrical connection between the rivet (30) and the outside may become unstable, which may lower the charging / discharging efficiency of the secondary battery (100) or cause safety issues.

[0150] To address these issues, a secondary battery (100) according to one embodiment of the present disclosure may further include a terminal plate (35). The terminal plate (35) is a wide, flat structure. The terminal plate (35) may be formed, for example, to surround the outer circumference of the rivet (30). The terminal plate (35) may be electrically connected to the rivet (30). Through this, the terminal plate (35) may provide a wider area in which the rivet (30) can be electrically connected to the outside. Accordingly, the rivet (30) may be stably connected to the outside. This will be described in more detail below.

[0151] According to one embodiment, the rivet (30) may include a rivet body (31), an upper support (32), and a lower support (33).

[0152] The rivet body (31) can be inserted into the first hole (20h) of the case (20). For example, the rivet body (31) can be formed in a cylindrical shape. The shape of the rivet body (31) is not limited thereto, and the rivet body (31) can include any shape that can be inserted into the first hole (20h) to electrically connect the first electrode and the outside, such as a polygonal column shape, a cylindrical shape, an elliptical column shape, etc. Hereinafter, for the convenience of explanation, a case in which the rivet body (31) is cylindrical will be described as an example. For example, the rivet body (31) can be a cylindrical shape with a solid interior. Alternatively, the rivet body (31) can be a hollow cylindrical shape with an empty interior.

[0153] The upper support portion (32) may extend outward from at least a portion of the upper outer surface of the rivet body (31). For example, the upper support portion (32) may extend outward from all sections of the upper outer surface of the rivet body (31). In this case, for example, when the rivet (30) is viewed from above, the upper support portion (32) may have a circular shape.

[0154] The upper support portion (32) can be formed by riveting the rivet body (31). For example, the rivet body (31) can be inserted into the first hole (30h) from the inside of the case (20) and exposed to the outside of the case (20). The rivet body (31) can have its upper side bent outward by riveting. The upper support portion (32) can be formed as the rivet body (31) bends outward. Accordingly, the shape of the upper support portion (32) can be formed in any shape, such as a circle, an oval, a distorted circle, etc.

[0155] The lower support portion (33) may extend outward from at least a portion of the outer circumference of the lower side of the rivet body (31). For example, the lower support portion (33) may extend outward from all sections of the outer circumference of the lower side of the rivet body (31). In this case, for example, when the rivet (30) is viewed from below, the lower support portion (33) may have a circular shape.

[0156] Through this structure, the rivet (30) can be inserted into the first hole (20h) of the can (20) and fixed to the can (30).

[0157] Meanwhile, the terminal plate (35) may be positioned between the case (20) and the rivet (30). Specifically, the terminal plate (35) may be positioned on the upper side of the upper surface of the case (20). In addition, the terminal plate (35) may be positioned on the lower side of the rivet (30). For example, at least a portion of the terminal plate (35) may be positioned on the lower side of the upper support member (32).

[0158] In order for the terminal plate (35) to be positioned between the case (20) and the rivet (30), a second hole (35h) into which the rivet (30) can be inserted may be formed in the terminal plate (35). The second hole (35h) may have a shape and / or position corresponding to the first hole (20h). For example, when the first hole (20h) has a circular shape when viewed from above, the second hole (35h) may also have a circular shape when viewed from above. For example, when the first hole (20h) is positioned vertically above the core of the jelly roll, the second hole (35h) may also be positioned vertically above the core of the jelly roll. With this structure, the rivet (30) can simultaneously penetrate the first hole (20h) and the second hole (35h).

[0159] At this time, the rivet (30) can be connected to the terminal plate (35) through riveting. For example, the rivet body (31) can pass through the first hole (20h) and the second hole (35h). The rivet body (31) can be connected to the periphery of the second hole (35h) through riveting. Accordingly, the upper support portion (32) can be fixed in a manner that is hung on the upper surface of the terminal plate (35).

[0160] At this time, in order for the upper support portion (32) to be better caught on the upper surface of the terminal plate (35), a catch portion (35d) may be formed on the terminal plate (35). As described above, the terminal plate (35) is a flat structure, and a structure in which a horizontal cross-section is formed wider than the height direction. For convenience, the area formed wide and flat on the terminal plate (35) will be referred to as a terminal plate body (35b). The catch portion (35d) is formed by extending from the outer circumferential surface on one side of the second hole (35h). For example, the catch portion (35d) may be formed to be concave from the outer circumferential surface on the upper side of the second hole (35h) toward the terminal plate body (35b). Accordingly, the catch portion (35d) and the terminal plate body (35b) may form a step when viewed from the second hole (35h). Additionally, the catch (35d) can be formed to correspond to the shape of the upper support (32). Accordingly, the rivet (30) can be fixed to the terminal plate (35) as the upper support (32) is caught as if inserted into the catch (35d).

[0161] In this way, the rivet (30) can be electrically connected through contact with the terminal plate (35). However, in this case, when the secondary battery (100) undergoes a chemistry process and charging and discharging occurs, the internal resistance may increase. For example, the internal resistance of the case (20) may increase.

[0162] In order to solve this problem, a secondary battery (100) according to one embodiment of the present disclosure can join a rivet (30) and a terminal plate (35) through a weld (w). The weld (w) can be formed when the rivet (30) and the terminal plate (35) are joined through welding.

[0163] The weld (w) can be formed by applying a predetermined amount of energy to the interface between the rivet (30) and the terminal plate (35). For example, the weld (w) can be formed through ultrasonic welding, laser welding, etc.

[0164] For example, the weld (w) can be formed through a single welding operation. Through this, the weld (w) can strongly connect the rivet (30) and the terminal plate (35) to each other.

[0165] Alternatively, for example, the weld (w) may be formed through two or more welding operations. For example, the weld (w) may be formed as an initial weld by first applying energy to the interface between the rivet (30) and the terminal plate (35). Then, the weld (w) may be formed as a final weld by applying energy again to the initial weld. In this way, when the weld (w) is formed through two welding operations, the weld (w) may have a smaller weld bead size than a weld formed through one welding operation. The weld (w) described below describes a weld formed through two welding operations.

[0166] More specifically, the weld (w) can be formed flat without a weld bead by being formed through two welding operations. Alternatively, the weld (w) can be formed in a state where the height difference between the weld beads is minimized with respect to the welding surface. Accordingly, the secondary battery (100) can provide a flattened upper surface even though the joining is performed through welding.

[0167] The weld (w) may be formed at least partially along the interface between the upper support (32) and the terminal plate (35). Accordingly, the upper support (33) may be joined to the upper surface of the terminal plate (35) via the weld (w). The position and / or shape of the weld (w) will be described in more detail in Fig. 7.

[0168] Meanwhile, the secondary battery (100) may further include an insulator (50). The insulator (50) may be positioned on the lower side of the terminal plate (35). In addition, the insulator (50) may be positioned on the upper side of the case (20). In this way, the insulator (50) may be positioned between the case (20) and the terminal plate (35) and may insulate the case (20) and the terminal plate (35). Accordingly, the terminal plate (35) may prevent a short circuit from occurring due to contact between the case (20) having the polarity of the second electrode and the terminal plate (35) and / or the rivet (30) having the polarity of the first electrode.

[0169] Through this structure, the secondary battery (100) can allow the rivet (30) to be more strongly bonded to the case (20). Alternatively, the secondary battery (100) can allow the rivet (30) to be more strongly bonded to the terminal plate (35). Accordingly, the secondary battery (100) can solve the problem of internal resistance increasing over time and also improve charge / discharge efficiency.

[0170] Fig. 7 is a plan view exemplarily illustrating a weld according to one embodiment of the present disclosure. Fig. 7 may be examples of various shapes, numbers, and / or positions of the weld (w) described in Fig. 6. Meanwhile, as described above, the weld (w) may be formed at least partially along the boundary between the rivet (30) and the terminal plate (35). Specifically, the weld (w) may be formed along the interface between the upper support (32) and the upper surface of the terminal plate (35).

[0171] Figure 7 (a) illustrates an example in which a weld (w) includes a weld line (wl1) formed along the entire interface. In this way, the weld (w) can be formed along the entire interface to join the rivet (30) and the terminal plate (35). Through this, the weld (w) can strongly join the rivet (30) and the terminal plate (35).

[0172] FIG. 7(b) shows an example in which the weld (w) includes one or more welding points (wp1) formed on a portion of the interface. At this time, unlike that illustrated in FIG. 6(b), the one or more welding points (wp1) may include one point, or may include two, three, five, or more multiple points. When the weld (w) includes multiple welding points (wp1), the multiple welding points (wp1) may be positioned at equal intervals from each other. Through this, the weld (w) can join the rivet (30) and the terminal plate (35) in a balanced manner. Alternatively, when the weld (w) includes multiple welding points (wp1), the multiple welding points (wp1) may be positioned at random intervals from each other. Through this, the weld (w) can conveniently join the rivet (30) and the terminal plate (35).

[0173] Fig. 7(c) shows an example in which the weld (w) includes one or more weld lines (wl2, wl3) formed on a portion of the interface. At this time, unlike what is illustrated in Fig. 7(c), the weld lines (wl2, wl3) may include one line, or may include three, four, five, or more lines. When the weld (w) includes multiple weld lines (wl2, wl3), the multiple weld lines (wl2, wl3) may be positioned to be equally spaced from each other. Through this, the weld (w) can join the rivet (30) and the terminal plate (35) in a balanced manner. Alternatively, when the weld (w) includes multiple weld weld lines (wl2, wl3), the multiple weld lines (wl2, wl3) may be positioned to be randomly spaced from each other. Through this, the weld (w) can conveniently join the rivet (30) and the terminal plate (35).

[0174] Fig. 7(d) illustrates an example in which a weld (w) includes one or more welding points (wp2, wp3) formed on a portion of an interface and one or more welding lines (wl4). In this way, the weld (w) may also be formed in a mixed form of points and lines.

[0175] The weld (w) according to the embodiment of the present disclosure is not limited to the examples illustrated in FIG. 7. The weld (w) may be formed in various shapes, numbers, and / or positions capable of joining the rivet (30) and the terminal plate (35).

[0176] FIG. 8 is another example of a cross-sectional view of the upper side of a secondary battery according to one embodiment of the present disclosure. FIG. 8 describes an additional structure that can improve the performance of the secondary battery (100).

[0177] More specifically, the terminal plate (35) must have a thickness sufficient to withstand riveting applied to the connection with the rivet (30). In addition, the terminal plate (35) must have a thickness that can avoid being damaged by welding applied to the connection with the rivet (30). Through this, the secondary battery (100) can provide a lightweight, large capacity, and / or a flat upper surface of the secondary battery (100).

[0178] And in FIG. 8, r1 represents a first radius, which is the radius of the upper support portion (32) of the rivet (30), and r2 represents a second radius, which is the radius of the lower support portion (33) of the rivet (30). The upper support portion (32) has a first radius (r1) toward the outside from the center of the rivet body (31) (for example, when the cross-section of the rivet body (31) is circular, the center of the circle). In addition, the lower support portion (33) has a second radius (r2) toward the outside from the center of the rivet body (31). At this time, the second radius (r2) may be equal to or larger than the first radius (r1). When the second radius (r2) is formed to have the same size as the first radius (r1), damage to the gasket (51, first gasket) described below can be reduced. When the second radius (r2) is formed to be larger than the first radius (r1), the formation of the upper support portion (32) can be easier.

[0179] The secondary battery (100) may further include a gasket (51, first gasket). The gasket (51) may be formed of an insulating material. The gasket (51) may be formed of, for example, the same material as the insulator (50). However, the gasket (51) may be formed of a different material from the insulator (50), as long as it is formed of an insulating material.

[0180] The gasket (51) may be formed, for example, in a ring shape. The gasket (51) may surround the rivet (30) and insulate the rivet (30) from the case (20). For example, the gasket (51) may be fitted to the rivet body (31) to prevent the rivet body (31) from contacting the case (20). In addition, the gasket (51) may seal the interface between the rivet (30) and the case (20), which will be described later.

[0181] At this time, the secondary battery (100) can assist the gasket (51) by further including a protrusion (p). The protrusion (p) can be formed to protrude outward from at least a portion of the rivet (30). For example, the protrusion (p) can be formed to protrude upwardly by being provided on the lower support portion (33) as illustrated in FIG. 8. Alternatively, unlike as illustrated in FIG. 8, the protrusion (p) can be formed to protrude toward the side by being provided on the outer peripheral surface of the rivet body (31).

[0182] One or more protrusions (p) may be formed. For example, two protrusions (p) may be formed as illustrated in Fig. 8. However, only one protrusion (p) may be formed, or three or more protrusions (p) may be formed.

[0183] Furthermore, when the secondary battery (100) includes a plurality of protrusions (p), some of the protrusions may be provided on the lower support portion (33), and other some of the protrusions (p) may be provided on the outer circumference of the rivet body (31). Through this, the secondary battery (100) may enable the protrusions (p) to secure the insulating gasket (51) or further help seal the inside of the can (20).

[0184] Fig. 9 is a graph for showing the change in the internal resistance (IR) of a case (20) over time in a secondary battery (100). Fig. 9 (a) shows a case where a rivet (30) and a terminal plate (35) are joined through simple contact rather than welding, and Fig. 9 (b) shows a case where a rivet (30) and a terminal plate (35) are joined through laser welding via a weld (w). The multiple graphs shown in each of Fig. 9 (a) and (b) represent test results for multiple secondary batteries (100).

[0185] As can be seen from (a) of Fig. 9, when the rivet (30) and the terminal plate (35) are electrically connected through simple contact, the internal resistance of the can (20) increases over time. On the other hand, as can be seen from (b) of Fig. 9, when the rivet (30) and the terminal plate (35) are electrically connected through laser welding, the internal resistance of the can (20) does not increase over time or the amount of increase is minimal.

[0186] Fig. 10 is a cross-sectional view showing another example of an enlarged portion X of Fig. 5.

[0187] Referring to FIG. 10, a secondary battery (100A) includes a case (20) that houses an electrode assembly (10), a rivet (30) that is inserted into a hole (20h) formed on one side of the case (20) and electrically connected to the electrode assembly (10), and a gasket (51, first gasket) that is positioned between the rivet (30) and the case (20) and seals the case (20), and the first gasket (51) includes a first region and a second region having a roughness lower than or equal to the first region.

[0188] The secondary battery (100) may include at least one of an external insulating layer (50) provided between the rivet (30) and the case (20) and an internal insulating layer (90) provided on the lower portion of the case (20) to insulate between the electrode assembly (10) and the case (20).

[0189] The gasket (51) can seal the case (20) to prevent electrolyte from leaking out from the case (20). For example, the gasket (51) can seal the case (20) while being positioned between the case (20) and the rivet (30). In addition, the gasket (51) can electrically insulate the case (20) and the rivet (30).

[0190] For this purpose, the gasket (30g) may be formed of a polymer material. For example, the gasket (30g) may be formed of an insulating material such as rubber, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyoxymethylene (PFA), etc.

[0191] The gasket (51) can be arranged to surround the inner peripheral surface area of ​​the hole (20h) into which the rivet (30) is inserted. The inner peripheral surface of the gasket (51) can be in contact with the outer peripheral surface of the rivet (30), and the outer peripheral surface can be in contact with the outer peripheral surface of the hole (20h).

[0192] At this time, the secondary battery (10) is advantageous in terms of safety when the gasket (30g) seals the hole (20h) by closely contacting the rivet (30). Therefore, in this embodiment, the following method is proposed to strengthen the adhesion of the gasket (51) to the surrounding components.

[0193] According to one embodiment, the gasket (51) may include a first region and a second region having a roughness less than or equal to the roughness of the first region. In this case, the roughness may mean an arithmetic mean roughness (Ra) for surface roughness.

[0194] More specifically, the surface of the gasket (51) may include a first region and a second region having the same or different roughness. In this case, the first region and the second region are each one of the regions where the gasket (51) comes into contact with another component included in the secondary battery (100). Therefore, the first region and the second region may form a contact surface while coming into contact with another component.

[0195] For example, the first region may be a region of the surface of the gasket (51) where the gasket (51) comes into contact with a component comprising a polymer material. For example, the first region may form a first contact surface while coming into contact with the component comprising a polymer material. At this time, in order to improve the adhesive force between the gasket (51) and the component comprising a polymer material at the first contact surface, the gasket (30g) and the component comprising a polymer material may have a roughness within the same range.

[0196] For example, the first region has a first roughness. Accordingly, the component including the polymer material can have a roughness within the same range as the first roughness. Accordingly, as the contact area between the gasket (51) and the component including the polymer material at the first contact surface increases, the adhesive strength between the gasket (51) and the component can be strengthened without applying separate pressure.

[0197] At this time, the first roughness may be in the range of, for example, 0.01 to 2 μm. Accordingly, the component including the polymer material at the first contact surface may have a roughness of, for example, 0.01 to 2 μm.

[0198] Here, the same range includes a range that is identical or can be judged to be identical. For example, the same range may be a range within a margin of error of ±1.99 um.

[0199] At this time, the gasket (51) and / or the component including the polymer material may have roughness formed on the surface through blasting, laser etching, physical etching, chemical etching, brushing, and other material coating.

[0200] At this time, the component including the polymer material may include at least one of, for example, an external insulating layer (50) provided between the rivet (30) and the case (20) and an internal insulating layer (90) provided on the lower part of the case (20) to insulate between the electrode assembly (10) and the case (20).

[0201] Accordingly, the first region forms a first contact surface that is in contact with at least one of the outer insulation layer (50) and the inner insulation layer (90), and at the first contact surface, at least one of the outer insulation layer (50) and the inner insulation layer (90) can have a roughness in the same range as that of the first region.

[0202] For example, the first region may include at least one of B and C illustrated in Fig. 6. At the first contact surface, the first region may have a roughness of 0.01 to 2 um, and at least one of the outer insulating layer (50) and the inner insulating layer may have a roughness of 0.01 to 2 um.

[0203] For example, the second region may be a region of the surface of the gasket (51) where the gasket (51) comes into contact with a component comprising a metal material. For example, the second region may form a second contact surface while coming into contact with the component comprising a metal material. At this time, in order to improve the adhesive strength between the gasket (51) and the component comprising a metal material at the second contact surface, the gasket (51) may have a lower roughness than the component comprising a metal material.

[0204] For example, the second region has a second roughness. Accordingly, the component including the metal material may have a roughness greater than the second roughness. At this time, when pressure is applied to the second contact surface, the gasket (51) at the second contact surface can be tightly adhered to the component including the metal material, thereby preventing the formation of a void at the second contact surface. This can enhance the adhesive strength between the gasket (51) and the component including the metal material at the second contact surface.

[0205] At this time, the second roughness may be, for example, in the range of 0.01 to 2 μm. Accordingly, the component including the metal material at the second contact surface may have a roughness greater than, for example, 0.01 to 2 μm. For example, the component including the metal material may have a roughness of 0.1 μm to 20 μm.

[0206] At this time, the gasket (51) and / or the component including the metal material may have roughness formed on the surface through blasting, physical or chemical etching, and other material coating.

[0207] At this time, the component including the metal material may include, for example, at least one of the rivet (30) and the case (20). For example, the second region may include at least one of A, D, and C illustrated in FIG. 10. Accordingly, the second region forms a second contact surface that comes into contact with at least one of the rivet (30) and the case (20), and at the second contact surface, at least one of the rivet (30) and the case (20) may have a roughness greater than that of the second region.

[0208] Through this configuration, the secondary battery (100) can further improve the sealing force of the gasket (51).

[0209] Fig. 11 is a schematic drawing showing an example of the first contact surface described above with reference to Fig. 10. Fig. 12 is a schematic drawing showing another example of the first contact surface described above with reference to Fig. 10.

[0210] A secondary battery (100) according to one embodiment of the present disclosure includes a first component including a first polymer material, at least a portion of which is in contact with the first component, a second component including a second polymer material, and a third component including a metal material, at least a portion of which is in contact with the first component, wherein the first component may have a first roughness at a first contact surface in contact with the second component, and a second roughness that is less than or equal to the first roughness at a second contact surface in contact with the third component.

[0211] For example, the third configuration may include at least one of a case (20) that houses the electrode assembly (10) and a rivet (30) that is inserted into a hole (20h) formed on one side of the case (20) and electrically connected to the electrode assembly (10).

[0212] For example, the first configuration may include a gasket (51) that seals the rivet (30) to the case (20), and the second configuration may include at least one of an outer insulating layer (50) provided between the rivet (30) and the case (20) and an inner insulating layer (90) provided on the lower portion of the case (20) to insulate between the electrode assembly (10) and the case (20).

[0213] Alternatively, for example, the first configuration may include an outer insulating layer (50) provided between the rivet (30) and the case (20), and the second configuration may include a gasket (51) sealing the rivet (30) to the case (20).

[0214] Figures 11 and 12 schematically illustrate the first contact surface. The first contact surface is a surface formed when the first configuration (P1) and the second configuration (P2) come into contact with each other. The first contact surface is a contact surface between the configurations (P1, P2) including polymer materials.

[0215] As illustrated in Fig. 12, if the roughness between the first configuration (P1) and the second configuration (P2) is outside the same range, a void may be created between the first configuration (P1) and the second configuration (P2). The fit between the opposing surfaces at the interface between the first configuration (P1) and the second configuration (P2) may not be properly bonded. Accordingly, the sealing force between the first configuration (P1) and the second configuration (P2) may be reduced.

[0216] Therefore, as illustrated in Fig. 11, it is preferable that the second configuration (P2) at the first contact surface have a roughness within the same range as that of the first configuration (P1). In this case, the first configuration (P1) and the second configuration (P2) can be interlocked with each other to increase the contact area. Accordingly, the sealing force between the first configuration (P1) and the second configuration (P2) can be improved. For example, the first roughness may be 0.01 to 2 μm, and the second configuration at the first contact surface may have a roughness of 0.01 to 2 μm.

[0217] FIG. 13 is a schematic drawing showing an example of the second contact surface in the example described above with reference to FIG. 10.

[0218] A secondary battery (100) according to one embodiment of the present disclosure includes a first component including a first polymer material, at least a portion of which is in contact with the first component, a second component including a second polymer material, and a third component including a metal material, at least a portion of which is in contact with the first component, wherein the first component may have a first roughness at a first contact surface in contact with the second component, and a second roughness that is less than or equal to the first roughness at a second contact surface in contact with the third component.

[0219] For example, the third configuration may include at least one of a case (20) that houses the electrode assembly (10) and a rivet (30) that is inserted into a hole (20h) formed on one side of the case (20) and electrically connected to the electrode assembly (10).

[0220] For example, the first configuration may include a gasket (51) that seals the rivet (30) to the case (20), and the second configuration may include at least one of an outer insulating layer (50) provided between the rivet (30) and the case (20) and an inner insulating layer (90) provided on the lower portion of the case (20) to insulate between the electrode assembly (10) and the case (20).

[0221] Alternatively, for example, the first configuration may include an outer insulating layer (50) provided between the rivet (30) and the case (20), and the second configuration may include a gasket (51) sealing the rivet (30) to the case (20).

[0222] Fig. 13 is a schematic diagram illustrating an example of a second contact surface. The second contact surface may be a surface formed when the first configuration (P1) and the third configuration (M) come into contact with each other. Alternatively, the second contact surface may be a surface formed when the second configuration (P2) and the third configuration (M) come into contact with each other. In Fig. 13, the first configuration (P1) and the second configuration (P2) are collectively referred to as P, and hereinafter, P is referred to as a “polymer configuration.” The second contact surface is a contact surface between a polymer configuration (P) including a polymer material and a third configuration (M) including a metal material.

[0223] As illustrated in Fig. 13, it is preferable that the third component (M) at the second contact surface have a roughness greater than that of the polymer component (P). When the second contact surface is formed with such a difference in roughness, when pressure is applied in a direction perpendicular to the second contact surface, the polymer component (P) can be deformed along the surface shape of the third component (M) and fit onto the surface of the third component (M). For example, the polymer component (P) can be deformed into a shape corresponding to the surface shape of the third component (M) and be strongly adhered to the third component (M). Accordingly, no empty space may be formed at the second contact surface. Accordingly, the sealing force between the polymer component (P) and the third component (M) can be improved.

[0224] For example, the first roughness may be 0.01 to 2 um, and the third configuration at the second interface may have a roughness of 0.1 um to 20 um. In this case, the first roughness represents the roughness of the polymer configuration (P).

[0225]

[0226] Roughness formation method

[0227] At least one of the first, second, and third components can form a desired degree of roughness on at least a portion of the surface, such as by blasting, physical and chemical etching, coating with another material, and / or surface treatment. For example, as described below.

[0228] At this time, the first configuration may include, for example, a gasket (51), an outer insulating layer (50), etc. At this time, the second configuration may include, for example, a gasket (51), an outer insulating layer (50), an inner insulating layer (90), etc. At this time, the third configuration may include, for example, a case (20), a rivet (30), etc.

[0229] 1) Sandblasting

[0230] - Sand spraying time: within 3 seconds

[0231] - Formable roughness range: 0.1~3.0um

[0232] 2) Sandpaper polishing (800 grit)

[0233] - Formable roughness range: 0.2~2.0um

[0234] 3) Carbon high temperature heat coating

[0235] - The target material is placed together with carbon and heat-treated at 1000℃ for 2 hours to coat the target material, and the target material includes a metal material.

[0236] - Formable roughness range: 0.1~1.0um

[0237] 4) Surface treatment

[0238] - At least one particle selected from a group consisting of organic particles, inorganic particles, and metal particles is collided with the surface of the target material together with the fluid to generate a scratch on the surface of the target material.

[0239] - Formable roughness range: 0.1~100.0um

[0240] One embodiment of the present invention can form roughness on at least a portion of the surface of each component included in a secondary battery (100) through such a method. Furthermore, one embodiment of the present invention provides a method for setting the roughness at the interface formed between components based on the materials included in the components. Through this, the secondary battery (100) can have a strengthened sealing effect and enhanced mechanical stability.

[0241]

[0242] Although the present invention has been described with reference to the embodiments shown in the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom.

[0243] Therefore, the technical protection scope of the present invention should be defined by the following patent claims.

[0244] It can be utilized in industries related to the manufacture of secondary batteries, especially lithium-ion secondary batteries.

Claims

1. An electrode assembly including a first electrode and a second electrode; A case electrically connected to the first electrode while housing the electrode assembly, having a first hole formed on one surface and an open surface on the other surface; a cap plate covering the opening of the case; and A secondary battery comprising a rivet inserted into the first hole and fixed to the case through a weld, and electrically connected to the second electrode.

2. In paragraph 1, Further comprising a terminal plate positioned on one side of the case and positioned between the case and the rivet, A secondary battery, wherein the terminal plate has a second hole formed at a position corresponding to the first hole so that the rivet is inserted.

3. In the second paragraph, the rivet, A rivet body; an upper support portion extending outwardly from at least a portion of an outer circumferential surface of an upper side of the rivet body; and a lower support portion extending outwardly from at least a portion of an outer circumferential surface of a lower side of the rivet body. The above rivet body is inserted into the second hole, A secondary battery in which the upper support portion is joined to the upper surface of the terminal plate through the welding portion.

4. In paragraph 3, A secondary battery, wherein the welding part includes one or more welding lines formed on the interface between the upper support part and the terminal plate.

5. In paragraph 3, A secondary battery, wherein the welding part includes at least one welding point formed on the interface between the upper support part and the terminal plate.

6. In paragraph 3, A secondary battery, wherein the above welding part includes one or more welding lines and one or more welding points formed spaced apart from each other on the interface between the upper support part and the terminal plate.

7. In paragraph 3, A secondary battery, wherein the terminal plate is formed by extending from the outer surface of one side of the second hole and further includes a catch portion corresponding to the shape of the upper support portion.

8. In paragraph 3, A secondary battery, wherein the upper support portion is formed with a first radius, and the lower support portion is formed with a second radius that is equal to or larger than the first radius.

9. In paragraph 1, A secondary battery further comprising an insulator positioned on the upper surface of the case and insulating between the rivet and the case.

10. In paragraph 1, A secondary battery further comprising at least one protrusion formed by protruding outward from at least a portion of the rivet.

11. A first composition comprising a first polymer material; a second component, at least a portion of which is in contact with the first component and which comprises a second polymer material; and At least a portion of the third component is in contact with the first component and includes a metallic material; A secondary battery, wherein the first configuration has a first roughness at a first contact surface in contact with the second configuration, and has a second roughness that is less than or equal to the first roughness at a second contact surface in contact with the third configuration.

12. In paragraph 11, The third configuration includes at least one of a case for housing an electrode assembly and a rivet inserted into a hole formed on one surface of the case and electrically connected to the electrode assembly. The first configuration includes a gasket positioned between the rivet and the case and sealing the case, A secondary battery, wherein the second configuration includes at least one of an outer insulating layer provided between the rivet and the case and an inner insulating layer provided at the lower portion of the case to insulate between the electrode assembly and the case.

13. In paragraph 11, The third configuration includes at least one of a case for housing an electrode assembly and a rivet inserted into a hole formed on one surface of the case and electrically connected to the electrode assembly. The above first configuration includes an outer insulating layer provided between the rivet and the case, A secondary battery, wherein the second configuration includes a gasket sealing the rivet to the case.

14. In paragraph 11, A secondary battery, wherein the second configuration at the first contact surface has a roughness in the same range as the roughness of the first configuration.

15. In paragraph 11, A secondary battery, wherein the third configuration at the second contact surface has a roughness greater than the second roughness.

16. In paragraph 11, A secondary battery, wherein the first roughness is 0.01 to 2 um, and the third configuration at the second contact surface has a roughness of 0.1 um to 20 um.

17. Case for storing the electrode assembly; A rivet inserted into a hole formed on one side of the case and electrically connected to the electrode assembly; A gasket positioned between the rivet and the case and sealing the case, A secondary battery, wherein the gasket comprises a first region and a second region having a roughness less than or equal to the first region.

18. In paragraph 17, It further includes at least one of an outer insulating layer provided between the rivet and the case and an inner insulating layer provided on the lower part of the case to insulate between the electrode assembly and the case. The first region forms a first contact surface that is in contact with at least one of the outer insulating layer and the inner insulating layer, A secondary battery, wherein at least one of the outer insulating layer and the inner insulating layer at the first contact surface has a roughness in the same range as that of the first region.

19. In paragraph 17, The second region forms a second contact surface that contacts at least one of the rivet and the case, A secondary battery, wherein at least one of the rivet and the case at the second contact surface has a roughness greater than that of the second region.

20. In paragraph 19, In the second contact surface, the second region has a roughness of 0.01 to 2 um, A secondary battery, wherein at least one of the rivet and the case has a roughness of 0.1 um to 20 um.

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